Video: The Value of Optimism on Climate and Energy (2:36)

It's a cold night. You wake up, curled in a little ball, shivering, and you remember that there is a nice, warm blanket in the hall closet. What do you do?

1. Stay in bed, because if you get up, your pajama pants, loose from your recent weight loss inspired by your lead role in the new blockbuster movie based on your bestselling novel, will fall off, and losing your pajama pants will make you colder than before.
2. Stay in bed, because if you get up, your significant other, the handsome/beautiful actor/actress (choose one of each) who will play the lead next to you in the new movie, will steal the covers already on the bed, you won't notice, and you'll end up colder than before.
3. Stay in bed, because if you get up, you'll spill the glass of imported water with the lemon slice that you keep next to the bed for your significant other, soaking the sheets and making you colder than before.
4. Get up and get the blanket.

If you picked D, you probably should be thinking about wise responses to global warming, because the physical basis for expecting that the ongoing human addition of carbon dioxide to the atmosphere will raise the Earth's average temperature is at least as strong as the physical basis for expecting warming from putting another blanket on the bed. It’s now extraordinarily unlikely that nature will do something bizarre enough to offset what we're doing—a huge number of volcanoes erupting and throwing things into the stratosphere to block the sun, or space aliens coming and getting in the sun's way—because we're putting a “blanket” on the planet, it is warming the planet, and we are almost guaranteed to get even warmer.

However, that doesn't tell us what, if anything, to do, so let's go take a look at the options. There's some money to be made here and disasters to be avoided, and good to be done.

Please note, the topics covered in Module 12 are appropriate for our course and do matter for your future. Old people like Dr. Alley were raised in a world in which these topics were not especially political; scientists did science, engineers did engineering, and voters, politicians, and businesspeople did their jobs without picking sides on the science and engineering. Many things happened over the last few decades, though, and the topics in Module 12 are considered to be political by many people today, even though most of the information is science, not politics.

We’ll try to give you a short enough version of the information to avoid overloading you or driving you crazy, but long enough to give you a good start if you want to know more. We will try to be scrupulous in avoiding taking sides on political issues… but recognize that in the modern politicized environment, it is impossible to even mention some of these issues without being accused of politicization by some people.

For what it’s worth, the progress in developing new energy sources has been so spectacularly fast that Dr. Alley remains optimistic, and he has put that optimism into a book, a three-hour TV miniseries, and various other outlets, including about 1000 public talks. The full scholarship does indicate that we can build a sustainable energy system that will supply more energy to more people at lower cost and with less environmental damage than from our current energy system, providing a larger economy, more jobs, improved health, and greater national security in a cleaner and more ethical world. If we remain committed over the next 30 years or so.

Learning Objectives

• Understand how different fossil fuels form, how slowly that occurs, and why, despite the huge value we get from the use of fossil fuels, we must move to other energy sources
• Explain how fossil-fuel burning contributes to climate change, which is making our lives harder, and thus how moving toward a sustainable energy system will help us to have a bigger economy, improved health, and other benefits
• Discuss reasons why maintaining or reestablishing natural ecosystems connecting national parks will help preserve the valuable biodiversity in those national parks.

What to do for Module 12?

You will have one week to complete Module 12. See the course calendar for specific due dates.

• Take RockOn #12
• Submit Exercise #6
• No StudentSpeak this week

Questions?

If you have any questions, send an email via Canvas to ALL the Teachers and TAs. To do this, add each teacher individually in the “To” line of your email. By adding all the teachers, the TAs will be included. Failure to email ALL the teachers may result in a delayed or missed response. For detailed directions on how to do this, see How to send an email in GEOSC 10 in the Important Information module.

This course is offered as part of the  Repository of Open and Affordable Materials  at Penn State. You are welcome to use and reuse materials that appear on this site (other than those copyrighted by others), subject to the licensing agreement linked at the bottom of this and every page. Students registered for this Penn State course gain access to assignments and instructor feedback and earn academic credit. Information about registering for this course is available from the Office of the University Registrar.

Overview of the main topics you will encounter in Module 12.

The difficulty lies, not in the new ideas, but in escaping from the old ones, which ramify, for those brought up as most of us have been, into every corner of our minds.

Prediction is very difficult—especially about the future.

Fuelish

• Plants use carbon dioxide, water, and the sun’s energy to grow more plant material while releasing oxygen.
• Other life forms “burn” the plants with oxygen to get that energy.
• If buried without oxygen, the plants aren't burned, and as nature heats them, they make fossil fuels:
  • With heating, woody plants become peat (which occurs in sediment; some of which is forming at Bear Meadows and in other wetlands) and then become lignite coal (which occurs in sedimentary rock) and then become bituminous coal (found in harder sedimentary rock, including in western PA) and then anthracite coal (found in metamorphic rock, in eastern PA) (some natural gas is also formed with coal);
  • Algae may be broken down by bacteria to make natural gas (some is produced in Bear Meadows), and with heating algae produce oil (often with natural gas, common in western PA), and then more heating breaks down the oil to produce more natural gas (eastern PA) (natural gas and oil float up and escape to be burned by bacteria, etc., unless trapped by geology).

Take It to the Limit

• Fossil fuels are NOT infinite:
  • Nature really is efficient at recycling, and most formerly living things were recycled rather than forming fossil fuels;
  • Oil & coal companies are really skillful, and already found easy-to-find fuels;
  • We have not set aside very much fossil fuel in parks or reserves (the oil likely to be produced if Arctic National Wildlife Refuge is opened to full drilling is estimated to equal less than 6 months of US use).
• World oil production is likely to peak soon (within decades?):
  • At vaguely recognizable prices and current demand, probably close to ½ century of oil and gas remain, and a few centuries of coal.

Impactful

• Fossil fuels do many important things for us.
• In the US, external energy use is 100 times what we can do for ourselves from energy in the food we eat; the world averages 25 times.
• External energy use is very important for our well-being.
• In the US and the world, most external energy is from fossil fuels.
• But, many negative impacts of fossil fuels, including health problems from air pollution from burning, accidental fires and explosions, leaks that hurt water supplies and wildlife, and climate change.

You’re in the Greenhouse Now

• Some gases in the air let visible light through (sun) but partly block infrared (energy returned from Earth to space).
• These gases make the planet warmer than it otherwise would be, so Earth “glows” brighter, forcing energy past the gases to space.
• We are increasing these gases (esp. carbon dioxide) a lot, and they will stay up for centuries, with some staying up 100,000 years and longer.

With High Confidence

• The greenhouse gases we release are warming the world and will continue to warm it, amplified by feedbacks such as the melting of reflective ice increasing warming.
• This is having and will have mostly negative impacts on us, making our lives harder:
  • Sea-level rise from ice melting and ocean water expanding;
  • More floods and droughts;
  • Dangerous, potentially fatal heat;
  • Strongest storms getting stronger;
  • Ecological displacements causing extinctions and spreading diseases;
  • Ethical issues—changes more dangerous for people less responsible for causing the changes;
  • Many more.
• Not much scientific disagreement on these points;
• But much political, social, and economic disagreement (similar political arguments about scientifically clear results have happened with previous environmental issues).

Making Money

• We have to switch from fossil fuels as they become scarcer; will we do so before or after we change the climate in ways that make life much harder?
• Sustainable alternatives are now often cheaper than the cost we pay directly for fossil fuels.
• And, economic analyses including the health and climate impacts show that fossil fuels are greatly subsidized, so the full price of fossil fuels to society is much higher than the direct cost (roughly double).
• Building a sustainable energy system is a huge task requiring decades, but can be done.
• And can improve the economy, employment, national security, health, environment, and ethics.

Lions and Tigers and Bears?

• Biodiversity is valuable to us as a source of medicines and other useful things we can discover, and because more diverse ecosystems produce more that we might use, and living types can serve as “canaries in the coal mine” to warn us of trouble, and diverse ecosystems motivate tourism that is economically important and fun; also, there are ethical issues of whether we have the right to kill off other species.
• Early and modern humans have been hard on biodiversity and contributed to extinctions, and we may be heading for the next mass extinction on the scale of the great mass extinctions of geologic history.
• Just as smaller islands have fewer species because it is easier to eliminate a smaller population, isolating patches of wilderness in separate national parks will turn them into biological islands and cause the loss of species in those parks.
• Climate change will make this worse, forcing migration when there may not be migration pathways.
• There are ways to avoid these problems, especially by maintaining natural connections between parks

A map and a female moose

Credit: R. B. Alley © Penn State is licensed under CC BY-NC-SA 4.0

The Arctic National Wildlife Refuge (ANWR) sprawls across the North Slope of Alaska, from the Brooks Range to the coast of the Arctic Ocean, and is nearly as large as the state of Maine. ANWR is home to grizzly and polar bears, wolves loping across the tundra, moose, vast flocks of waterfowl, and snowy owls ghosting on white wings. The Porcupine caribou herd lives in and migrates across ANWR and is used in the traditional lives of several groups of native people. But beneath ANWR, there probably is oil.

Let's visit The Arctic National Wildlife Refuge (ANWR): Where Caribou Meet Oil Conduits

Energy vs. Environment

The Alaska Pipeline, not too far from ANWR, has pumped billions of dollars’ worth of petroleum south from regions near the North Slope. But as that oil runs out, the pipeline may soon be left empty—a very expensive tube with nothing to carry. The similarity of geology suggests that ANWR also has oil to fill the pipeline, and to fuel automobiles in the U.S., or somewhere else in the world. There is not a lot of oil—maybe 10 billion barrels, according to the USGS, with maybe 1/3 of that likely to be produced over a few decades if production is allowed, according to the US Energy Information Agency. If so, then ANWR might supply a little under 6 months of US oil use, not especially important in the big picture. But, with oil having fluctuated between $50 and $100 per barrel for much of the 21st century, 6 months of US oil use represents more than $100 billion and maybe much more…a LOT of money. The argument between wilderness and development has been going on for decades, and is not likely to end soon. So, let’s look a little more closely at this, which is one of the most important issues for the coming decades, because our well-being depends on using fossil fuels now, and on stopping that use in the future.

Plants have an amazing ability. A towering redwood tree, or any other plant, is just carbon dioxide (CO₂) and water (H₂O) plus a few trace elements, put together with the sun’s energy. All plants that photosynthesize do this, releasing oxygen (O₂) in the process. The chemical composition of plants is, more-or-less, CH₂O, so an approximate chemical formula for photosynthesis is:

$C O_2+ H_{2}O + s u n^{\prime }s e n e r g y \to C H_{2}O + O_2$

Most of the rest of us—animals, fungi, many bacteria—as well as forest fires run this reaction backwards, combining plant material with oxygen to release energy, carbon dioxide, and water. Done rapidly, this is the “burning” of a fire; done slowly, it is still burning of a sort, which you might call "respiration." Plants usually include a little nitrogen and traces of other elements that we didn't write in the simplified formula above, and animals often use the plant material with its nitrogen and trace elements to make proteins that make animals, but after the animals die, they are almost always "burned" by bacteria or fungi or other animals that eat them to release the energy, and the equation is pretty close to what happens.

But, sometimes the dead materials end up in a place without oxygen. Then what? A little more “burning” can be done by microorganisms using certain other chemicals such as sulfate instead of oxygen, but all burning by living things stops when these other chemicals run out, too, and burning by fires does not occur in wet places. Then, the dead things may remain as unburned dead things for a long time. And, if a lot of dead things occur close together, fossil fuels—coal, oil, and natural gas—become possible.

Coal

Coal is formed when bacteria break down dead woody plants (trees, leaves, etc.). When and where there is no free oxygen in the air or water, bacteria remove the oxygen and hydrogen from the plant material, leaving mostly carbon and forming a brown material called peat. (Note that when gardeners talk about “peat”, they usually mean “peat moss”, a specially selected product made mostly of dead sphagnum moss. Peat moss is peat, but most peat would not be satisfactory for gardeners as peat moss.) When peat is buried by more sediment, it gets hotter as that sediment partially traps the Earth’s geothermal heat, which helps drive off more of the remaining oxygen and hydrogen, thus forming coal.

The classification of coal can become quite complex, but in common usage, coal is usually separated into lignite, bituminous, and anthracite. Lignite or brown coal has not been cooked too much; it is common in the western United States. Bituminous coal is formed from lignite by heat and pressure and is common in many places including western Pennsylvania. In a few places including eastern Pennsylvania, closer to the center of the old Appalachian Mountains, the bituminous coal was cooked to metamorphic anthracite coal. Peat is found with loose sediment, lignite with not-too-hard sedimentary rock, bituminous with harder sedimentary rock, and anthracite with metamorphic rock.

Oil and Natural Gas

Oil has similarities to coal, but oil is formed mostly from dead algae buried in mud, usually from marine settings but sometimes from lakes. Other dead things may be involved in oil formation as well, but they were “slimy” rather than woody in life. Please note that dead dinosaurs or other large creatures have never been important in fossil-fuel formation; there just aren’t enough large creatures at any time to supply the immense amounts of carbon needed to make economically exploitable fossil-fuel deposits.

Algae start with more hydrogen and less oxygen than wood, so the fossil fuel they produce ends up with chemicals containing mostly carbon and hydrogen (usually called hydrocarbons), different from the mostly-carbon coal that forms from woody plants. If mud containing dead algae is buried deeper by more sediment, heat breaks down the algae to release liquid oil. More heat breaks down the oil and makes natural gas, which is primarily methane (CH₄). (Some natural gas also is made at low temperatures by bacteria before the algae and mud are buried too deeply, and some natural gas is made during the formation of coal.) While the heat is making oil and gas, the mud is being squeezed to make shale.

Pennsylvania contains some oil and natural gas, and the first modern oil well was drilled in western Pennsylvania in the year 1859. Humans had used petroleum before then, but from natural seeps rather than wells. Indeed, that first Pennsylvania oil well was drilled where oil was leaking out of the ground and had been used by native people for a long time. That first oil well was motivated in part by a looming shortage of whale oil for lamps to light homes on dark nights, because the demand for whale oil far exceeded the ability of the oceans to grow whales. (People also used a biofuel that was a mixture of alcohol and turpentine in lamps, but it was even more explosive than the kerosene that came from the oil, and thus was quite dangerous.)

Where We Find Fossil Fuels

As noted above, early humans found fossil fuels where they leaked out of the ground. At certain oil seeps, after some of the oil evaporated or was used by bacteria, a sticky material was left behind that trapped animals in “tar pits”. Native people probably harvested these trapped animals at what is now the La Brea Tar Pits National Natural Landmark in California, and at other such tar pits elsewhere, in addition to using the oil and tar in other ways. But, to get the huge quantities of fossil fuel we use today, we cannot wait for it to leak out of the ground; we have to go down and get it.

Coal is usually found in layers between layers of other rocks. Early coal mining generally involved digging out the coal from these layers and hauling it to the surface, using supports to prevent roof collapses (which sometimes occurred anyway). Increasingly, coal mining is done by digging giant open pits, stripping off the materials above the coal and dumping them elsewhere, then digging up the coal. Such “strip mining” has large environmental costs.

Most oil and gas are formed in shale, which is made from mud. The shales that are rich in dead algae and thus produce a lot of oil and gas often appear dark in color and are called “black shales”. The mud that makes up the shale has very small particles with very small spaces between them, and oil and gas do not move rapidly through those small spaces unless the shale is broken. Because of this, much of the oil and gas that originally formed in these shale layers is still in them.

We humans have recently become much more efficient at getting oil and gas out of these black shales, in a process generally called “fracking”. An oil company will drill down to a black shale layer, and then use some impressive technologies to turn the drill and bore along inside the layer. Then, the borehole is pressurized enough to break the surrounding shale, and water, sand, and various chemicals are squirted into the new cracks to keep them open and enhance the ability of the oil and gas to move through the new cracks, as shown in the first panel of the diagram below. Oil and gas are then pumped out of the well, as shown in the second panel.

But much of the original oil and gas long ago escaped from where they formed in the shale. Probably most of that original oil and gas has been lost entirely, as described soon, but some of it has been trapped elsewhere. Traditionally, most oil and gas came from oil companies drilling into this oil and gas that migrated to traps.

Gas or oil take up more space than the dead algae they came from, and so as they form, they tend to push on the surrounding shale and help break it, often aided by mountain-building stresses or other stresses in the Earth. Most of these fractures will let some oil and gas out of the shale and then re-seal as the weight of sediments above squeezes them back together and often as new minerals are deposited in the cracks. This keeps much of the oil and gas in the shale and makes it difficult for other oil, gas, and water to move through the shale layers.

Oil and gas are low in density and float on water or vent into the air. So, when they escape from a black shale layer, they tend to rise through water-filled pores in rocks and escape at natural seeps on land or beneath the sea. In some places such as in the Gulf of Mexico, strange biological communities have been found living on oil seeping out of the sea floor. (Oil is natural, and some species “like” oil in small quantities. But if a supertanker wrecks or an oil well blows out, nature cannot use that much oil all at once, and large problems for nearby living things usually result.)

Because of the tendency for oil and gas to escape, a large accumulation of oil outside of black shale can form only if there is a trap of some sort. Many different types of traps exist. For example, the figure below shows one common type of trap.

Deposition of shales often occurred alternating with sandstones, as you saw at the Grand Canyon, so it is common to see a pile of sedimentary layers that goes shale-sandstone-shale-sandstone, and so on. As shown in the diagram, mountain-building processes often folded the layers in such a pile. Then, oil and gas escaping from a deep black shale layer rose into the spaces between grains in the sandstone above, but were trapped by a shale layer above that.

Geoscientists have worked for decades to design better ways to find such special places so that wells can be drilled into them to extract the oil from the sandstone, as shown. Extracting the trapped oil and gas is easier than fracking, and fewer wells can produce more fossil fuels for longer times, thus making more money for the oil company if the geoscientists are really good at finding the special places. If the geoscientists don’t find the special places or the drillers don’t hit the special places, a “dry hole” results and millions of dollars may have been wasted on drilling. Oil companies have hired more geoscientists for decades because the geoscientists have been so efficient at doing their jobs.

At present rates of use, and at costs vaguely similar to what we see today, the oil and gas will last maybe half a century, and the coal for more than a century. If we were willing to pay more for gasoline, say $50 per gallon, more fossil fuels would be available. As discussed below, that would cause very large and very damaging climate changes, as well as other damaging impacts.

Impacts of Fossil Fuels

There are a few references at the end of the Module if you want to follow up on the topics introduced here.

We use fossil fuels for good reasons. Most of our energy is obtained from fossil fuels. We run washing machines, rather than hand-scrubbing our clothes, primarily with fossil-fuel energy. Most of us are freed from the manual labor of hoeing and plowing to grow our food because fossil-fueled tractors plow and plant and cultivate and harvest. Many of us have been freed from freezing to death in the winter, or perishing of heat stroke in the summer, or dying because we can’t get to the hospital in an emergency, because of fossil fuels. In the US in recent decades, slightly more than 80% of our external energy use was supplied by fossil fuels. And, our energy use in that time was about 100 times as much as the energy from our food—what is done for us by external energy, mostly fossil fuels, is 100 times more than we can do for ourselves. This is a HUGE difference, and an important reason why we live as well as we do. (For the world over the same time, the average is about 25 times more external energy than energy from food, with a similar fraction of slightly more than 80% from fossil fuels.)

For humans, and for the few types of domesticated animals and plants that have benefited from our use of fossil fuels (pigs, rice, chickens and soybeans, for example), there is little question that fossil fuels have been good. For other species on Earth, our use of fossil fuels to tame much of the planet has been less beneficial. How much easier did fossil-fueled trains make it for humans to travel west to shoot bison? How much easier is it to cut a tree with a fossil-fueled chain saw than with a stone hatchet? However, this is complicated by the fact that we have let some trees grow back, and we quit burning whales (or whale oil) to light evenings because we switched to burning the long-dead algae and trees that are fossil fuel.

There clearly are other costs of fossil-fuel use. Damage to tundra from oil exploration may last decades or longer. Acid rain, mainly from coal-fired power plants, killed the trout in headwaters streams in the Great Smoky Mountains National Park and in some other places including in Pennsylvania. Smog is not good for us and shortens our lives. A study published in 2021, for example, found that 20% of global deaths were caused by breathing fine particles released by fossil-fuel burning. (Other studies have found somewhat different numbers, and there are ways to clean up much of this pollution without completely stopping the use of fossil fuels, but there is no doubt that burning causes air pollution that hurts health, and that much of our burning is fossil fuels. We will see soon that fossil-fuel use is also making forest fires worse, further increasing the health risks.)

The list could go on. Interstate 95 was closed twice in less than a year for extended periods because bridges were damaged by the resulting fires when fuel tankers crashed. Various insurance and government data coming out in the early 2020s showed that gasoline-powered cars, with their explosive fuel interacting with electrical systems (spark plugs, batteries, lights, …) were 10-100 times more likely to catch on fire than electric-only cars. Leaks from gasoline storage tanks or other fuel and oil leaks have contaminated groundwater in many places. Carbon dioxide released by fossil-fuel burning is acidifying the ocean and endangering many species. Earthquakes are often triggered when salty, somewhat-radioactive fluids that are recovered from fossil-fuel wells are pumped back into the ground for disposal. This is far from a complete list. And, as discussed in the next section, climate change caused by fossil-fuel use is probably the biggest issue, with potentially immense costs.

There can be no doubt that anything we do to get large amounts of energy will have unintended consequences, and that we could make a long list of problems with energy sources we might use to replace fossil fuels, such as nuclear or hydroelectric or geothermal or wind or solar or waves or tides or…. There is an increasingly rich scientific and engineering literature, though, showing that a sustainable energy system can be built that will supply more energy at less total expense and with fewer unintended consequences than the one we have now, which is really good news. We cannot possibly cover this whole topic in this course, but we’ll return to it a little before we finish this Module. Be assured, though, that there can be good outcomes from what may seem like a really bad situation.

Because the Earth contains a limited supply of fossil fuels, and we are using them up rapidly, and it will take ~100 million years or more for nature to make a lot of new ones, we must replace fossil fuels with some other energy sources or face really huge problems. But, if we burn most of the fossil fuels that still exist in the Earth and let the carbon dioxide accumulate in the atmosphere before building a sustainable energy system, we will live in a really different climate that will make our lives much harder. The scientific community knows this really well. Several lines of information are involved, starting with the effect of carbon dioxide on the greenhouse effect.

If not for the greenhouse effect, we humans probably would not be here. The Earth’s atmosphere allows the shortwave radiation (what we usually call "sunlight") coming from the sun to pass through to the Earth’s surface, without too much interference. (There is a little interference. Among other things, blue light is scattered off air molecules a bit more than red light is, so the blue light bounces around in the atmosphere and reaches our eyes from all directions in the sky, whereas the red comes more directly from the sun, which is why the sky is blue.) The windows in a greenhouse similarly allow sunlight to enter easily.

But, the sunlight heats the Earth or the inside of a greenhouse, which then radiates longwave radiation (infrared radiation) back upwards. As we saw way back at the Redwoods, the total energy reaching the planet on average equals the total energy leaving, but the arriving energy is mostly shortwave electromagnetic radiation (light that we can see) while the leaving energy is mostly longwave electromagnetic radiation (infrared radiation that we cannot see without special sensors). The windows of a greenhouse do not allow longwave radiation to pass through easily; some gets through, but some is trapped.

When the sun rises after a cold night, energy enters a greenhouse but has trouble leaving, and the extra energy warms the greenhouse. Warming makes the floor of the greenhouse emit more longwave radiation, forcing some through the glass until a new balance is reached between incoming and outgoing radiation, but with the greenhouse at a higher temperature than would occur without the windows of the greenhouse. Some gases in the atmosphere act in the same way as the windows on the greenhouse, intercepting some of the outgoing infrared longwave radiation and keeping that energy in the Earth system. As described in the Enrichment, carbon dioxide really is the most important greenhouse gas, even though water vapor intercepts more of the outgoing radiation from the Earth; methane and some others also matter. Without these greenhouse gases in the atmosphere, the Earth would be mostly frozen.

Human-Caused Greenhouse Warming

Human activities are increasing the concentrations of greenhouse gases in the atmosphere. Carbon dioxide, mostly from the burning of fossil fuels and also from the burning of forests and a few other sources, is by far the most important greenhouse gas, because of its direct effects and because the air warmed by the carbon dioxide picks up more water vapor, also a greenhouse gas. In the USA in the early part of the 21^st century, fossil-fuel burning produced about 15 tons of carbon dioxide per person per year! The greenhouse-gas methane, which is produced in cow guts, landfills, rice paddies, and other places where plant material or other carbon-carrying compounds break down in the absence of abundant oxygen, also has been increasing, and human activities also are increasing a few other less-important greenhouse gases.

The world is undoubtedly warming, as shown by thermometers, including thermometers far from cities and in weather balloons and on satellites, in the ground and in the ocean, analyzed by government and university scientists and other scientists in many different countries, including with industrial funding. The thermometer records are confirmed by changes in temperature-sensitive types of snow and ice, NOT the top of Antarctica at -50^o, which won't melt even with a fairly large warming, but we see reductions in seasonal river and lake ice, seasonally and "permanently" frozen ground, springtime snow, mountain glaciers, the edges of the Greenland and Antarctic ice sheets, and more. The vast majority of significant changes in where plants and animals live, and when during the year they do things, are also in the direction expected from warming.

Furthermore, there is very high confidence that the observed warming is from the observed rise in carbon dioxide. The physics is unavoidable; rising carbon dioxide causes warming. This basic understanding of the greenhouse effect, and the role of carbon dioxide and other gases, was worked out in the 1800s, with the first calculation of the warming effect of fossil-fuel burning in 1896. That was before quantum mechanics was discovered; newer calculations using quantum mechanics are more precise. Much of the important quantum-mechanical work on this subject was done by the U.S. Air Force after World War II. They were not primarily studying global warming, but instead were worrying about such things as the appropriate sensors on heat-seeking missiles to shoot down enemy bombers. (With the wrong sensor, the missile wouldn’t "see" the infrared radiation from the hot exhaust of the enemy engine because carbon dioxide is in the way.) And, carbon dioxide interacts with infrared radiation going from Earth to space in the same way. Satellites confirm this every day. Indeed, before satellites were invented, scientists predicted what satellites would see when they were launched and looked back at the energy leaving the Earth, and those predictions were right.

Any scientist who could find a true alternate explanation of the warming would help humanity, and would immediately be famous and receive awards and speaking invitations and other good things; thus, you can be sure that many scientists have tried very hard to find some other explanation for some or all of the observed warming. As noted next, there are some other small influences on temperature, but a lot of effort has totally failed to change our understanding that the carbon dioxide we are releasing is the primary driver of climate change now.

Nature did contribute a little to the warming in the early 1900s, when a few decades passed without major sun-blocking volcanic eruptions and when, coincidentally, the sun brightened a little. But, warming continued after that even though the sun dimmed a little and a few volcanic eruptions threw up particles that cooled the climate by slightly blocking the sun, and as humans put up a lot of particles from smokestacks that also blocked the sun. Humans also caused a little cooling by cutting down a lot of dark sun-absorbing forests and replacing them with more-reflective surfaces, but the warming continued anyway.

We know from geologists and other scientists studying climate history recorded in ice cores and other archives that climate is not significantly influenced by natural changes in cosmic rays, space dust, Earth’s magnetic field, or anything else weird; and, we know that none of these are changing much now anyway. Changes in features of Earth’s orbit are important in changing climate, as we learned back in Module 7 with Milankovitch cycles and ice ages, but over “short” times of centuries or less the orbital changes are too small to affect climate significantly, and in addition, we are at a point in the cycles when the changes are naturally small. Extra heat is not coming out of the ocean or land or ice to warm the air; instead, heat is moving out of the air to warm the ocean and land and melt ice, yet the temperature of the air continues to rise. The Pacific Ocean flips back and forth between El Niño and La Niña, shifting the climate a little warmer and then cooler over a few years, but this cannot create trends in climate, only fluctuations around the trend from other causes.

Furthermore, the "fingerprint" of the warming in space and time is just what is expected from the effects of rising carbon dioxide, and completely unlike the pattern expected from changes in the sun, volcanoes, El Niño, or other natural fluctuations. For example, adding carbon dioxide to the air warms near the Earth’s surface but cools high in the stratosphere where the radiation emitted by the extra carbon dioxide can escape to space and thus cool off other gases in the air, but turning up the sun would warm the stratosphere as well as the surface; the data clearly show the carbon-dioxide pattern of warming down here but cooling up there. Computer models of the climate system, when forced only with the known natural causes of climate change such as changes in the sun and volcanoes, do a good job of simulating the climate changes that happened before greenhouse gases had risen much but do a lousy job of simulating more-recent changes after human emissions of carbon dioxide became large; adding those human-caused effects allows the models to simulate what happened quite accurately up to the present, with rising carbon dioxide most important.

The climate models have repeatedly proven to be accurate, predicting future changes accurately and “retrodicting” past changes without cheating, so those models give us clear guidance for the future. If we continue to burn fossil fuels and release the carbon dioxide, and we don’t do extensive geoengineering by taking immense amounts of carbon dioxide out of the air or else doing the huge task of imitating the volcanoes and blocking the sun ourselves, we will continue to see warming and other changes.

When carbon dioxide rises, direct warming is unavoidable from the basic physics. And, the warming causes other changes, which in turn affect the climate in what we call feedbacks. For example, snow and ice reflect a lot of the sun’s energy, and so help keep the Earth cooler than we otherwise would be. Warming from rising carbon dioxide tends to melt the reflective snow and ice, exposing darker dirt or plants that absorb more sunshine, which causes more warming. The most important feedback is from water vapor—putting warmer air over the vast ocean causes the air to pick up more vapor, which is a greenhouse gas itself and causes more warming.

In total, if we put up enough carbon dioxide to warm the climate by one degree, the actual warming will be roughly three degrees, with uncertainties that include a little less, a little more, or a good bit more, but not a good bit less. For more on feedbacks and uncertainties, and for the stabilizing feedbacks that will eventually remove the carbon dioxide we release over ½ million years or so, go to the Enrichment.

So What?

Few people really care about the average temperature of the Earth, but many people care about how changes in that temperature will affect humans and other living things. Impacts are harder to estimate than temperature change, both because of the additional uncertainties involved in estimating how the temperature change will affect the economy and ecology, and because of the involvement of human values. For example, if warming causes species to become extinct, but those species were not economically important, how bad is that? You will find really strong differences of opinion across the political spectrum in the U.S. and the world, with some people really unhappy that we are driving species to extinction and other people apparently not very concerned. (The value of species will be addressed later in this Module.)

Some disagreement probably should be expected about some aspects of climate change. The climate in many places is already too hot for humans and many of our animals and crops to live comfortably; making these places hotter will not be good for us. Other parts of the world, generally with many fewer people, are too cold for comfortable human habitation today, so warming them could be good for the humans living there, although there will be much bad for them as the melting ice floods their coasts, and melting ice in permafrost causes their roads and buildings to settle and break, and warming makes it harder for native peoples there to preserve their traditional lifestyles, and…. Note that most of the use of fossil fuels that drives warming is done by relatively wealthy people living in colder places, while the greatest harm will be done to poorer people in hotter places, raising large ethical issues.

A few of the big impacts of more warming include:

• Too much heat. If we continue to rely on fossil fuels, later this century some parts of the Earth could have heat waves that will be fatal to all unprotected people—a healthy person sitting naked in the shade in the wind drinking water will die from overheating. Long before then, heat stress to people, their animals and crops may drive climate refugees unless major adaptations are made such as exceptionally widespread installation of air conditioning. We already are seeing an increasing number of deaths from overheating, despite the fact that nowhere has yet become hot enough to be truly unsurvivable for a careful, healthy person.
• More floods and more droughts. Warmer air carries more water vapor, picked up from the vast ocean as well as from the land surface, and thus warmer air can generate more, faster rainfall when conditions are right, causing flooding. Clothes dryers and hair dryers have heating elements to dry faster, and in the same way, warmer air can bring on more droughts faster after the rain stops.
• Sea-level rise. Warming ocean water causes it to expand, and warming melts mountain glaciers and the edges of the great ice sheets, releasing their stored water that eventually reaches the ocean.
• Strong storms becoming stronger, because more energy is available to them.
• Ecological displacements. This is expected to cause extinction of many species, and may spread diseases to new places (malaria is limited by cold, for example, and so its spread will be favored by warming).
• More forest-fire weather, with the potential for western-type fires spreading into places including the Appalachians where such fires have not been observed or prepared for.
• And much more.

Note that costs go up much faster than the temperature. With a little bit of sea-level rise, for example, we deal with “nuisance flooding” by staying away from certain flooded roads at certain times, but otherwise we go on with our lives. A little more sea-level rise, though, will require highly expensive engineering in some places to keep salt water out of our drinking water, or will require abandonment of some roads and neighborhoods and even whole cities or else expensive engineering to protect them. Thus, the warming so far has not been hugely expensive because we started with some capacity to adapt to it, but we are using up that adaptive capacity, and the full scholarship shows clearly that costs will rise rapidly with further warming.

Uncertainties

There are of course uncertainties in all of this, but these uncertainties really provide a strong argument for working harder to reduce future warming, not a reason to wait until we’re more certain. And, they provide a strong argument for more research to reduce the uncertainties.

Here’s a short video explaining the uncertainties related to climate change, and a few thoughts on what this might mean to us.

Video: Uncertainties (3:44 minutes)

First, consider an analogy to a familiar issue—estimating how long it will take to drive somewhere, and how much the trip will cost. Suppose your phone tells you that a trip will take an hour with current traffic. If all goes well, and the traffic clears, you might save five minutes, and maybe you’re a really good driver and can save five more minutes. But, if things go wrong, you might be run over by a drunk driver and never make it at all, or arrive three weeks later after you get out of the hospital. The uncertainties include outcomes that are a little better, a little worse, or a lot worse than your most-likely estimate, but not a lot better. Your response to these uncertainties includes buying a car with crumple zones and antilock brakes and air bags, and putting on your seat belt to protect you, and if you’re transporting a baby putting them in an approved safety car seat, and paying police to arrest drunk drivers, and perhaps you donate to Mothers Against Drunk Drivers—you spend a lot of money on something you do not expect to happen, because it could happen and would be devastating if it did happen.

Uncertainties with climate change are often similar. Drs. Anandakrishnan and Alley study the possibility of ice-sheet collapse and sea-level rise. With warming, the expansion of ocean water and melting of mountain glaciers is virtually guaranteed to raise sea level, giving roughly ½ m (1.5 feet) of rise by the year 2100 under small warming, 1 m (3 feet) of rise by 2100 under large warming, and uncertainties of about ⅓ the rise…if the ice sheets behave. But, if certain possible events actually happen, the rise could be double or triple that, or even more, with no really good possibility to offset the really bad one. With costs are rising faster than sea level, and the uncertainties including the possibility that too much warming will cause very large, rapid sea-level rise, the costs could go up immensely. We will return to economics next, but the uncertainties do motivate more effort now to slow down the warming, and more research now to reduce the uncertainties.

Fortunately, we really do have solutions for the great challenges of supplying energy sustainably and economically. This is NOT the course to deal with all the nuances of future energy systems, a hugely important topic but too big for a portion of one Module in a course on the Geology of National Parks. A few key facts follow, though. Note that your course authors don’t really know the exact future of the energy system; if we did, we could turn that knowledge into a lot of money!

The single biggest development in energy has been the immense reduction in the cost of renewable energy. Solar panels that cost more than $100 in 1975 fell to about 25 cents in less than 50 years. The International Energy Agency, founded in 1974, spent decades being unenthusiastic about renewable energy, but by 2020 reported that state-of-the-art solar installations were supplying the lowest-cost electricity in human history, with wind close to solar in price. The energy that must be “invested” to make new solar cells and wind turbines is very small compared to the electricity they then produce, and probably is smaller than the investment needed to find and develop new fossil fuel deposits, helping explain why the costs of renewable electricity have dropped below costs from fossil fuel.

Although the land area (or ocean area) needed to supply all of human energy use from renewable energy sources is large, it is very small compared to the areas we use for some other purposes. For example, we grow food to eat, to feed animals, and to burn as biofuels (corn ethanol, biodiesel, etc.). Biofuels are a small part of our energy mix, much less than fossil fuels, but installing modern solar cells and wind turbines on the area we use for growing biofuels could supply more energy than is used by all humans from all sources because renewables are so much more efficient than plants at capturing the sun’s energy. Some farmers are choosing to combine wind or solar energy (or both) with ranching or farming, increasing farm income. But, renewables do not need to take farmland at all, and instead can be put across irrigation canals to reduce evaporation, above parking lots to shade them, offshore where the foundations can be designed to help provide fish habitat, and in other places.

Renewables have real needs in addition to land or ocean area, including materials, some of them rare. But, geologists remain confident that we can find sufficient materials that, with recycling, can supply a sustainable system involving much less mining and drilling than are required with fossil fuels. And, materials scientists remain confident that they can shift to reliance on more abundant elements, so the geologists don’t need to find more rare things for mining. For example, sodium batteries are already beginning to replace lithium batteries in some uses, and sodium is MUCH more common than lithium and so requires much less mining.

As noted above, anything that we do to supply the huge amount of energy we use will have unintended consequences. Wind turbines do kill some birds, for example, although the number is tiny compared to human-caused deaths from other sources including the current energy system. A full analysis, including the effects of climate change and the disturbances associated with fossil-fuel recovery, shows that switching to a sustainable energy system rather clearly will reduce overall bird deaths. And, we can now forecast and monitor major bird migrations, turning off wind turbines in important places at the right times to further reduce mortality (Sovacool, 2013)

The future energy system might include fusion if we invent that technology, or nuclear fission if costs can be brought way down and other problems can be solved, or geothermal energy, or some others. Biofuels may remain important for some hard-to-replace uses of liquid fuels such as long-haul airlines. So much energy is available at such low cost from renewables, though, that we know a sustainable system can be built, supplying affordable, clean energy for everyone across the world.

Sovacool, Benjamin K., "The avian benefits of wind energy: A 2009 update." Renewable Energy, Volume 49, 2013, doi:10.1016/j.renene.2012.01.074.

Fossil fuels provide great value, which we pay for, but also cause health problems and climate change, which generally are not included in the costs of fossil fuels. How important is this?

Economic analyses consistently indicate that reducing fossil-fuel use would be economically beneficial. The Nobel Prize in Economics in 2018 was given to William Nordhaus of Yale for building new types of models that provide guidance to policymakers and the public on optimal ways to distribute money among consumption now, broad investment to grow the economy and give future people the ability to solve problems, and targeted investment in issues such as climate change to reduce the problems that we leave for future people. Those models show that great improvements to the economy are available if we reduce fossil-fuel use efficiently.

A team working with the International Monetary Fund used these tools, and various other standard economic approaches, to estimate the costs to society of subsidizing fossil fuels. Some of this is direct subsidies such as tax breaks, but mostly it is the fossil-fuel damages we discussed above, from lost health and from climate change, that are not paid for by the fossil-fuel users. The International Monetary Fund group found that the subsidy for fossil fuels in 2015 was 6.5% of the world economy (gross domestic product), or $5.3 trillion. Seven years later, that had increased to $7 trillion, or 7% of the economy. As a rough approximation, for each dollar spent on fossil-fuel energy, society spends another dollar. Clearly, this varies with the costs of fossil fuels, and is higher for some countries and lower for others, but it is a useful first approximation. Governments almost always are involved with any large part of the economy, and there generally are taxes and subsidies scattered throughout the economy, but the size of this fossil-fuel subsidy dwarfs others. Note that the uncertainties mean that these fossil-fuel subsidies could be a little smaller, or a little bigger, or a lot bigger than stated here, but not a lot smaller.

Because the real cost of fossil-fuel energy is so high, there are strong economic reasons to move towards a sustainable energy system. Studies are repeatedly showing that with maybe 30 years of work, we can eliminate at least 90% and perhaps 100% of the global-warming emissions at a cost that is cheaper than continuing to rely on fossil fuels.

Again, we can guarantee that you can find heated arguments about everything we have written on this topic, and many things we have not written. We have tried to provide the best evidence. Dr. Alley has worked extensively with the United Nations Intergovernmental Panel on Climate Change, winner of the 2007 Nobel Peace Prize, as well as with the US National Academy of Sciences on some aspects of this, and has relied heavily on those sources and on other high-quality scholarship for the material presented here. Any energy transition will be a huge effort, and we don’t know in detail what really will be included in a sustainable energy system. But, the scholarship now really does show that this can be accomplished in ways that help the economy, increase employment, improve health and national security, and provide a better environment more ethically.

A few good sources

• For our note about the land area used for biofuels being able to supply all human energy use with renewables, start with Adeh EH, Good SP, Calaf M, Higgins CW. Solar PV Power Potential is Greatest Over Croplands. Sci Rep. 2019 Aug 7;9(1):11442. doi: 10.1038/s41598-019-47803-3. PMID: 31391497; PMCID: PMC6685942. They concluded that “Global energy demand would be offset by solar production if even less than 1% of cropland were converted to an agrivoltaic system.”
• This paper noted that roughly 4% of arable land is used for biofuels, Rulli, M., Bellomi, D., Cazzoli, A. et al. The water-land-food nexus of first-generation biofuels. Sci Rep 6, 22521 (2016). https://doi.org/10.1038/srep22521
• The International Monetary Fund estimate of fossil-fuel subsidies is from Coady, D., Parry, I., Sears, L., & Shang, B. (2017). How large are global fossil fuel subsidies?. World development, 91, 11-27; an update in 2023 was at https://www.imf.org/en/Publications/WP/Issues/2023/08/22/IMF-Fossil-Fuel-Subsidies-Data-2023-Update-537281
• To start learning about the economics of climate change and the value of moving away from fossil fuels, you might try William Nordhaus’ 2018 Nobel Prize lecture on the economics of climate change https://www.nobelprize.org/prizes/economic-sciences/2018/nordhaus/lecture/
• For temperature data, a good starting point is the NASA Goddard Institute for Space Studies GISTEMP site, with lots of graphics, raw data, and much more. https://data.giss.nasa.gov/gistemp/
• Probably the most important source on this topic is the United Nations Intergovernmental Panel on Climate Change, winner of the Nobel Peace Prize in 2007, at www.ipcc.ch Everything they do is open and archived, which is really wonderful, but means that there is a LOT of material. A useful starting point might be to look at the Summary for Policymakers of the Physical Science Basis of report, https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM.pdf
• In addition to the Physical Science Basis, the IPCC provides reports on what climate change will do to us, and what we can do to reduce or eliminate our influence on the climate. Just the Summary of only the physical science section is 31 pages, so you can be sure there is a LOT of information there, assembled by the world’s scientists, in the public eye, working as volunteers, to provide guidance on climate.
• The US National Academy of Sciences and the Royal Society have some great resources at the National Academies of Science. Dr. Alley helped just a little with this one.

Island Biogeography, Yellowstone and Avoiding the Next Mass Extinction?

Most of the national parks were established to preserve geological features. A few parks, such as Sequoia and Redwood, were established for biological reasons. Increasingly, however, national parks are visited, used, preserved, and managed for biodiversity. Humans continue to spread. More and more land is brought under cultivation. More of the produce of the sea is netted and served to humans.

A 2023 study showed how grossly humans now dominate, finding that the world has just 20 million tons of wild land mammals (white-tailed deer, elephants…) and 40 million tons of wild marine mammals (whales…), compared to 390 million tons of humans and 630 million tons of domestic livestock (cows, pigs…). That makes 60 tons of wild mammals but 1020 tons of domestic mammals, 17 times more!

As we will discuss below, extinction is more likely for smaller populations, and with over 6000 species of wild mammals, the populations of most of those species are quite small and thus prone to extinction. Different mammals have different requirements for food, water, and other resources, but the differences are not huge because we are all closely related mammals, so this 17-fold difference in domestic versus wild mammals translates into a huge difference in the share of the world’s resources used, with humans increasingly overwhelming nature.

Greenspoon, Lior, Eyal Krieger, Ron Sender, Yuval Rosenberg, Yinon M. Bar-On, Uri Moran, Tomer Antman et al. "The global biomass of wild mammals." Proceedings of the National Academy of Sciences 120, no. 10 (2023): e2204892120.

Let's take a trip through Yellowstone, the Premiere Park

We briefly visited Yellowstone in Module 1, as the world’s first national park, and we went back to Yellowstone in Module 2 to discuss earthquakes. Yellowstone was indeed established to protect the geologic features, which were so rich, varied, and unusual that the early explorers found them hard to believe. The geysers, mud pots, hot springs, canyons, waterfalls, petrified trees, inside-out caves, and so much more cause many of us to believe that this is still the world’s best national park. But, if you chat with the rangers or with visitors, you will immediately recognize that people are deeply committed to the wildlife of Yellowstone. A ranger at any entrance station or a visitor’s center will spend the day fielding questions along the lines of “Where are the bears? Where are the wolves? Where are the moose? Where are the…?”

According to the National Park Service, Yellowstone hosts nearly 300 species of birds, 16 species of fish, five species of amphibians, six species of reptiles, and 67 species of mammals—including seven native ungulate species (elk, mule deer, bison, moose, bighorn sheep, pronghorn, and white-tailed deer; mountain goats are not originally native to Yellowstone but now occur in the north side of the park as well) and two bear species (black and grizzly). Badgers and bobcats, lynx and otters, and so many more species are found in the park. Along the Hayden Valley in the center of the park, or in the Lamar Valley to the northeast, or really almost anywhere in the park, a visitor who takes a little time to slow down, and especially one who goes out early morning and late evening, is almost guaranteed to have wonderful views of wildlife.

Yellowstone played an important role in saving the bison, which were hunted almost to extinction. In 1894, US soldiers arrested a poacher named Edgar Howell, and a photograph of the damage he had done proved to be essential in motivating Congress to pass additional protections for Yellowstone and the wildlife there. Full implementation of that act was some time in coming, and the population of bison in Yellowstone dropped to perhaps 23 animals or so, but, they survived, and Yellowstone is the only place in the lower-48 states that has had free-ranging bison since prehistoric times, with a modern herd that fluctuates a good bit but is generally around 5000 animals.

This is a geology class, and biodiversity may seem to be a bit far-afield, but there are many, many links between our class and biology, so let’s take time for a quick detour. We saw that there have been mass extinctions in the past—times when many living types became extinct in a short interval. We are making decisions now that will control whether a geologist far in the future will identify our time as another mass extinction, the end of the Cenozoic and the start of the Anthropocene.

Early humans were surprisingly hard on biodiversity. Wherever humans arrived with their efficient tool kits—in Australia, New Zealand, other islands, the Americas—extinctions of large animals followed. Direct human hunting, or competition from the rats, pigs, dogs, and others that arrived with the humans, likely contributed. The Smithsonian Museum of Natural History Hall of Deep Time shows that arrival of modern humans had smaller effects where humans and animals had long coexisted (extinction of 7% of large animal species—more than 50 kg or 110 pounds—in Africa and 18% in Eurasia), but huge impacts where animals were not already familiar with us (extinction of 74% of large animal species in North America, 82% in South America, and 97% in Australasia).

Some people don’t like the idea that early humans were hard on biodiversity. Many people, including good scientists, have argued that the extinctions of large animals in the Americas were caused by climate change, which happened to occur at about the same time as human arrivals in some places. Dr. Alley has listened to talks in which data he helped produce were used to argue that the climate changes were so large and rapid that they must have been responsible. But, the work by Dr. Alley and others showed that the animals lived through dozens of such abrupt climate changes before going extinct just after modern humans arrived. Climate change probably did reduce populations of many species, but that also occurred at each of the earlier abrupt climate changes that did not cause extinction, so a human role in the extinctions is unavoidable.

The earlier extinctions were mostly of large creatures. Since the industrial revolution, “modern” humans have contributed to the extinction of various creatures. And, the rate of extinction may pick up soon as we increasingly occupy the planet. To see why, let’s take a little detour into island biogeography.

Island Biogeography

If you were to visit a lot of different-sized islands that are more or less the same distance from the mainland, you would find that the bigger islands have more species. Roughly, an island with ten times the area of another will have twice as many species. If you visited islands of about the same size at different distances from the mainland, you would find that those closer to the mainland have more species.

At least some of what controls these observations is not too difficult to understand. If you have a small island, it can hold only a few individuals of a species. From year to year, populations go up and down depending on food supply, predators, and other things. With a small population, a small drop can hit the absorbing boundary of zero individuals and cause extinction, but a large population can survive a small drop. So, extinction is more likely on a smaller island, causing smaller islands to have fewer species. The mainland is there to supply new individuals to islands to replace those that die, swimming across or floating across on logs or in other ways, and repopulation is easier for islands closer to the mainland, so those islands closer to the mainland have more species.

These patterns of island biogeography are well-established. Studies of the repopulation of islands sterilized by volcanic explosions, and even of very, very tiny islands that were deliberately depopulated and then allowed to come “back to life,” have shown that this is the way the world works naturally.

Now, think about Yellowstone. Originally, the boundaries drawn for the park separated wilderness inside from wilderness outside. Today, as shown in the satellite photo, some of the park boundaries are easy to see from space because loggers outside the park work right up to the boundaries. Yellowstone remains connected to other wilderness regions in other directions; it is not an island (yet), and indeed, some of the logging shown here is being replaced by regrowth of trees that have not yet been logged again.

But what if Yellowstone were an “island,” as some other parks are or soon may be? Suppose a park becomes surrounded by farmland, which is used to feed humans and keep us alive. Farmland does not support a lot of wild orchids or other rare species. Farmland is impoverished in biodiversity, with just a few species, carefully selected to feed us. A park surrounded by farmland is in some ways an island, because many species have great difficulty crossing the farmland just as many species have difficulty crossing the ocean. And, from the well-established principles of island biogeography, the isolation of a parkland from other wilderness will cause extinctions in the park. Perhaps more worrisome, if the only remaining wilderness is in parks, there is no longer a “mainland” to replace species lost to local extinction on the island—extinction in the park is then extinction from the world, as shown in the video below.

We know that as the climate changed in the past, plants and animals migrated long distances to stay with their preferred climate. As the climate changes in the future, migration will be required but may be impossible if the parks become isolated.

We can use a cartoon terrarium to illustrate some of the basics of island biogeography, and how isolating Yellowstone and Glacier from each other could cause extinctions in both. Have a look at this short video.

Video: Small-Scale Biodiversity (1:51 minutes) 

Let's take a look at some charismatic macro fauna

So, Who Cares?

One can ask whether biodiversity is worth preserving. This is proving to be a difficult topic and one that will be discussed much in the future.

To start, we can easily list many reasons why biodiversity is good and should be preserved.

• Many of our medicines have come from plants, and if many plants become extinct before we can study them carefully, we are likely to lose many possible medicines.
• Engineers and designers are increasingly using “biomimetic” techniques—mimicking nature. Evolution has worked over vast times to select the most successful biological patterns, and we can learn from them, if they are here to be learned from.
• More diverse ecosystems seem to be a little more productive and more reliable (if you have hot-loving and cold-loving and wet-loving and dry-loving types in a region, then something will grow well no matter what weather arrives; if you have only one type, and the weather is bad, so is the crop), so if producing more is good, biodiversity seems good.
• Living things have frequently served as “canaries in coal mines”. Miners would take a canary along in the mine, not only for companionship, but because the birds were more sensitive to bad air than were people, and a sick or dead bird would warn miners to get out before the miners became sick or dead. Birds of prey served that function for us with DDT. This chemical was being used to kill pests, increase crops, and wipe out diseases—until the falcons, hawks, eagles, and other predatory birds started disappearing. A little DDT on a plant led to more DDT in an insect that ate lots of plants, and still more DDT in a bird that ate a lot of those insects, and became so concentrated in a falcon that ate the birds that the falcon’s eggs broke and young ones couldn’t be raised. It became clear that such “bioconcentration” threatened humans as well—the other living things gave us a warning. Loss of biodiversity means loss of warning sensors.
• Many people like diversity, and pay a lot to go see it in different countries and in zoos, supporting an important industry.
• And, for many people, this is an important moral or religious issue—do we really have the right to terminate the existence of other living things, that some people believe were put here by a deity that likes those things?

Some planners today are trying to establish corridors connecting wilderness areas, so that the parks do not become islands and lose species. How successful this plan will be remains to be seen. The “simple” answer is that to maintain many species on Earth, we have to maintain much wilderness. And that in turn has implications for how we humans choose to behave. The 30 by 30 initiative has been adopted by the US Government as of 2021, seeking to protect 30% of land and of sea habitat by the year 2030.

As an aside, some of our friends over in meteorology are not happy that the effect of CO₂ on climate is called the “greenhouse effect.” They fully understand that CO₂ does warm the planet, and they know that the glass of a greenhouse affects radiation in much the same way that CO₂ in the atmosphere does—the shortwave radiation from the sun comes through glass or CO₂ more easily than the longwave radiation from the Earth goes out through glass or CO₂. But, the meteorologists note that this effect of glass on radiation is not the only reason why a greenhouse is warm, nor is this the major reason. Greenhouses also are warmer than their surroundings because the glass blocks the convection currents (air rising after it is heated a little) that take much of the sun’s heat away from the ground outside of greenhouses. Some meteorologists have even suggested renaming the atmospheric phenomenon to avoid possible confusion. But, the “greenhouse effect” is catchier than “the effect that warms the Earth through modulation of radiation balance, akin to the radiative effect that contributes to but does not dominate daytime warming of greenhouses.” Notice that this little discussion about terminology in no way affects the reality that more CO₂ in the atmosphere warms the planet—nature works, regardless of what words we use to describe it.

How Much CO₂ to Warm?

Many different models have been constructed of the Earth’s climate system, ranging from attempts by large teams to include essentially all Earth-system processes into models that tax the world’s largest computers, to small-group or individual-scientist efforts to build fast and flexible models that allow exploration of uncertainties in many parameters. Across a range of models, the equilibrium surface warming from a doubling of CO₂ is often stated to be between about 2^oC and 4.5^oC, with a central value near 3^oC (and with the most recent results pointing to a bit above 3^oC). Comparisons to the past, for both the last century and for much longer times, largely exclude the low end of that range—models that change global average temperature less than 2^oC or just slightly more than that for a doubling of CO₂ are not able to accurately simulate the changes of the past, whereas models with larger temperature change in response to CO₂ do better in simulating past changes. Based on the paleoclimatic record, warming of near 3^oC or more for a doubling of CO₂ seems reasonable, and values above 4.5^oC cannot be totally excluded.

Note that this distribution of warming includes a central estimate, and the possibility of somewhat less, somewhat more, or even more than that, but not even less. In the physics, this arises in part because the feedbacks (discussed more just below) act on each other. Raising atmospheric CO₂ causes warming. That in turn causes more water vapor to evaporate, which causes more warming. And, it causes snow and ice to melt, causing more sunshine to be absorbed, which causes more warming. And, the warming from more water vapor causes some snow and ice to melt, and the warming from less snow and ice causes more water vapor to evaporate, causing still more warming. This does not “run away”—we are not yet close to turning the Earth into Venus, hot enough to melt the metal lead at the surface. But, we cannot avoid the warming from CO₂, and the interactions mean that if our models have slightly underestimated the effects of the feedbacks, the models will have notably underestimated the total warming.

Note also that many of the damages have a similar distribution—for some specified warming, the expected sea-level rise has a central estimate, and could be a little less, a little more, or a lot more. And economics gives a similar answer—for some specified sea-level rise, there is some central estimate of costs, which could be somewhat less, somewhat more, or much more, but not much less (for example, economists often assume we will behave efficiently and follow the least-cost approach to solving the challenges of a rising sea, but observations of people actually responding to challenges indicate that we often are not following the most efficient path). With this same general set of uncertainties for the warming from given CO₂ release, and damages from the warming, and costs of the damages, the possible costs if a lot of things go wrong could be really high.

More on Feedbacks

Recall from earlier that feedbacks are important in estimating how much warming will be caused by the CO₂ we emit, and as we noted just above, feedbacks are behind the possibility of warming being much greater than generally expected. If you force a system to change by doing something to it, many other things may then change. Some of these will amplify what you just did, making the changes bigger than you could have accomplished by yourself; these are positive feedbacks. Others will oppose what you just did, making the changes smaller than what you initially forced; these are negative feedbacks.

You, for example, have all sorts of negative feedbacks built in. If you are placed in a warmer room (the forcing), your body will begin to warm up. But then a negative feedback kicks in—you start to sweat, and that cools you off. Your body temperature doesn’t change nearly as much as the temperature outside of you changed. But, if you have certain diseases, they may fool your body so that its negative feedbacks are reduced and may even become positive feedbacks. Fever is usually a good thing, helping the body fight invading germs more effectively, but people die of fever when the feedbacks become too positive and the body “burns itself up.” If you’re in a canoe with a really enthusiastic golden retriever, you may try to lean as the dog leaps about in such a way as to stabilize the canoe—you are providing a negative feedback on the tipping. But if the dog tips the canoe, and the ice chest falls to the low side, the ice chest is acting as a positive feedback to amplify the dog’s motion and tip the canoe further. If you lose your balance when the dog lunges to the side, you may suddenly fall toward the dog, providing another positive feedback and perhaps flipping the canoe.

The Earth certainly has positive and negative feedbacks. The easiest stabilizing or negative feedback is the very fast change in radiation—a warmer place glows more brightly almost instantaneously and sends more heat toward space, tending to cool the hotter places faster. Other than this almost-instantaneous change, most of the climate feedbacks over times that are most important to us (years through thousands of years) are positive, amplifying changes. Over still-longer times approaching or exceeding one million years, the feedbacks tend to be negative, stabilizing the climate. Climate changes over years or centuries thus can be almost as large as climate changes over millions or billions of years.

The most important very-long-term stabilizing feedback was discovered by Penn State’s famous professor Jim Kasting and coworkers. Recall that any chemistry lab has a Bunsen burner or a hotplate to speed up the chemical reactions so you can get done before the class period ends—chemistry almost always goes faster at higher temperature. Rock weathering involves CO₂ and water reacting with rocks to make dissolved ions that wash away to be turned into shells or the inorganic equivalents, which over millions or billions of years are subducted, melted, and returned to the surface in volcanoes that release rocks and CO₂ and water to complete the cycle. The rate of subduction and volcanic eruption does not depend very much on the climate at the Earth’s surface, but the rate at which weathering removes CO₂ from the air goes faster when warmer. So, if the temperature goes up, removal of CO₂ from the atmosphere goes faster, cooling the temperature back down. And, if the temperature goes down, the removal of CO₂ slows but the volcanoes continue to supply CO₂ at the same rate, so the CO₂ builds up in the atmosphere and warms the climate. However, if something perturbs the climate, such as us releasing a lot of CO₂, this takes more than 100,000 years to return the climate to its original state. Note also that this natural volcanic flux of CO₂ is about 1% of the human supply primarily from burning fossil fuels; the ongoing rise in atmospheric CO₂ is NOT caused by volcanoes!

There may be a second very slow stabilizing feedback. Warming reduces the amount of oxygen dissolved in water, which reduces the ability of animals, bacteria, etc. living in the deep ocean to “burn” dead organic material, favoring burial of those dead things to eventually form fossil fuels rather than “burning” of the dead material to release the CO₂ back to the ocean-atmosphere system. Again, this is slow, and removing the CO₂ we release will take well over 100,000 years.

Most of the other feedbacks that operate between these very long times and the nearly instantaneous changes in radiation with temperature are positive, amplifying the effect of the original forcing. If we put carbon dioxide into the air and warm the Earth a little, several of these positive feedbacks begin to function. Most importantly, warmer air can “hold” more water vapor (the saturation vapor pressure roughly doubles for a 10^oC or 18^oF warming), and water vapor is an important greenhouse gas, so warming causes more warming.

Some of the shortwave radiation from the sun that hits the Earth bounces right back to space without first warming the Earth, especially over snow and ice, which have very high albedo or reflectivity. But, warming the Earth removes some snow and ice, which then allows more of the shortwave radiation to be absorbed, which warms the Earth more—a positive feedback.

Clouds reflect some sunlight (so cloudy days are cool), but clouds also interfere with outgoing longwave radiation (so cloudy nights are warm). The largest uncertainties in predicting how much warming will result from a given amount of fossil-fuel burning are probably related to how clouds will change, and whether these changes will produce positive or negative feedbacks. However, these uncertainties are not nearly large enough to affect the conclusion that future warming from fossil-fuel burning is highly likely, and the evidence is now fairly strong that the cloud feedbacks are also positive, with various shifts in cloud types and locations that in total amplify the warming. Vegetation also may change, affecting how much water vapor it returns to the atmosphere and affecting albedo, but this does not seem to be an especially strong feedback.

Climate Models

We clearly wish to predict the future. The knowledge that burning of fossil fuels, combined with bovine belches and a few other greenhouse-gas sources, are nearly certain to cause large problems allows us to change our ways now to improve our future well-being. To predict the future, we need to do experiments. But, we have only one world. We cannot look at many different futures of one physical world, nor do we wish to wait many decades for the experiments to end. The solution we use is to build little worlds in computers, and run the experiments on those.

Note first that this sort of modeling is used everywhere all the time. In one old Calvin and Hobbes cartoon, Calvin asked his dad how load limits were determined for bridges, and his dad said that they drove heavier and heavier trucks over a bridge until it broke, then weighed that truck and rebuilt the bridge. This is of course nonsense; the strength of the bridge is calculated in a model. Your automobile and cell phone were designed on models, too. “It’s just a model” is the sort of thing said by people who aren’t paying attention, and who might be wise to start paying attention.

Anyway, geologists are important in many ways in this effort to model the climate, with two contributions especially important: finding out how the world works, and finding out what has really happened. The computer models always will be simpler than the real world, so careful choices must be made about what to put in, and things put in must be represented accurately; hence we need to know how the world works. And, once the models are built, we need to test them. You wouldn’t trust a model that had never been tested, but you wouldn’t want to wait a whole lifetime for a test. If the models can successfully simulate very different, warmer and colder climates of the past, then the models are probably pretty good. So we need to know about climates of the past, and geologists help supply those data.

The computer models of today actually are doing very well at “retrodicting” climate, predicting things that already happened. Modelers set up the configuration of ice sheets and ocean and continental positions and orbits and solar brightness, then model the climate and see if the computer results can match the climate that is recorded by the fossils and other climatic indicators in the rock record without “cheating” (so the scientists do not go in and tweak a lot of things to make the model match the data and then claim that the model is great—the models actually do work on past climates without such cheating). The models are also doing quite well at predicting the patterns of change we have observed with instruments over the most recent decades. Predictions made by modelers over the last decades are really occurring now.

Models predict that the world will warm about 3^oC or just over 5^oF for a doubling of the concentration of CO₂ in the atmosphere. The full warming will be delayed a few decades behind the rise in CO₂, because the air can’t warm all the way until the ocean and ground have warmed and some ice has melted, which takes a while. The global warming to date, somewhat over 1^oC or 1.8 ^oF in the early 2020s, has only recently become obviously bigger than the typical temperature variability at most places, so it is only recently that the warming has become obvious to a lot of people. If we proceed to burn all the fossil fuels, though, roughtly an 8-fold increase in atmospheric CO₂ above “natural” levels is possible over a century or centuries, or a warming of about 9^oC or over 16^oF, large enough that no one would have any doubt about the change. (Note that the land warms more than the ocean, and almost everyone lives on land, so people are experiencing a notably larger warming than this.) The recent drop in cost of renewable energy has caused most experts to conclude that it is unlikely we will burn that much fossil fuel, but there still is a large likelihood that we will push warming past 2^oC unless strong actions are taken soon.

Why Not Water Vapor?

Water vapor is the most important greenhouse gas in terms of the amount of outgoing infrared radiation intercepted, and thus the amount of warmth provided. But, we usually start discussions of global warming with CO₂, not water vapor. Why? Simply, water vapor is almost entirely a slave to CO₂. Put some more CO₂ up in the atmosphere, and the atmospheric concentration of CO₂ remains much higher for centuries, and somewhat higher for more than 100,000 years before chemical processes remove it. Put more water vapor up, and in just over a week, on average, that water has rained out. The burning of fossil fuels makes approximately equal numbers of water-vapor and CO₂ molecules, but because the water vapor stays up less than two weeks and the CO₂ perhaps 2000 years on average, our effect on the atmospheric concentration is more than 100,000 times larger for CO₂ than for water vapor. We can change CO₂ fairly easily (and are doing so!), but we can’t put up water vapor fast enough to make much of a difference, nor can most other natural processes affect global water-vapor loading very much. However, changes in the atmosphere’s water-vapor content are easily caused by changes in temperature.

Remember from back at the Redwoods that cooling reduces the equilibrium water-vapor pressure or “water-holding capacity of the air” (by about 7% per degree Celsius of cooling). Remember that as full-of-water air came in from the Pacific and was forced up over Redwood National Park and then Yosemite and Sequoia National Parks, the air cooled by about 0.6^oC/100 m, raining on the way. The temperature at the top of the Sierra was controlled by the height of the Sierra and the temperature of the air before the rise began, and the amount of water left in the air at the top was controlled by the temperature at the top. The air then goes down over Death Valley, and the water-vapor content of the air there depends on the temperature at the top of the Sierra.

So, if the temperature is increased over the Pacific by an increase in CO₂, the water-vapor content and its greenhouse effect are increased over the Pacific, going up the Sierra, going back down over Death Valley, and on to the Atlantic or Gulf of Mexico. Water vapor acts as a positive feedback—warming increases the water-vapor content of the atmosphere, causing more warming.

You can find lots of climate-change skeptics or contrarians or denialists who love to point out that water vapor is the big greenhouse gas, CO₂ less so, so the scientists must be wrong to focus on the small one and not the big one. Sounds sensible, right? But, it is totally stupid or deliberately misleading, or somewhere in-between. If we pulled all the water vapor out of the air, more would evaporate in a week or so. Pull all the CO₂ out of the air, and the cooling would remove a lot of water vapor, with a rather high chance that the whole Earth would freeze over into a snowball. Thus, although water vapor gives us more warmth than CO₂, the CO₂ is more important overall.

Why All the Noise?

Environmental problems seem to follow a fairly predictable path. First, someone has a good idea. Refrigerators and air conditioners and freezers are useful, but if you use ammonia in the pipes and you’re in the way when a pipe breaks, you might die, so chlorofluorocarbons were a great idea. Then, scientists discover an unintended consequence—the chlorofluorocarbons might break down ozone and allow harmful ultraviolet rays to give living things “super-sunburns,” causing cancer and other problems. There follows a period when the scientists work to improve their understanding.

But, there also follows a lot of yelling and not-entirely-scientific discussion. Some people fear that they are going to lose their jobs, or lose a lot of money, if the problem-causing industry is changed, and these people respond to the scientists by arguing that there is no problem, that the problem that does not exist must be caused by nature rather than humans, and that this natural problem that does not exist would cost way too much to clean up, and that the clean up would involve taking actions that we all will hate and are probably illegal and are promoted by crazy people who hate us. A very common approach is to attempt to convince the public, or policymakers, that scientists are still having a big debate, even if they are not. It is fairly easy to find a few skeptics, fund them and promote their statements, and to “cherry-pick” certain results from the scientific literature and present them out of context.

Politics often feeds into this. Usually, if a problem is identified that affects a lot of people, the government ends up dealing with the problem. You are not allowed to tear out your sewer or septic system, poop in a pot, and dump it over the fence into my yard. Nor are you allowed to smoke in many public places now, or dump your trash in my yard, and laws such as these are passed by and enforced by the government after they are demanded by many people. So, if you don’t much like government, you may think that it is unwise to have the government trying to clean up a problem. And, if you can keep the argument focused on whether or not the science is good, rather than on possible wise responses to the problem, there is little danger that the government will do anything—we usually don't do much about a problem until we agree that there is a problem.

The press makes all of this worse, attempting to maintain "balance" by presenting “both sides” of a “scientific dispute,” even if one side is being manufactured and does not have much scientific basis of its own. Recent scholarship has demonstrated clearly that a reader of the mainstream press in the U.S. would have a very skewed view of the degree of scientific agreement over global warming, for example—many press outlets present a conflict that really doesn’t exist.

But, some forward-looking people also see the problem as a possibility—a new invention may make a lot of money and help a lot of people. And, history indicates that problems usually are followed fairly quickly by new inventions, the cost of dealing with the problem typically is much less than previously stated (often about 10% of the previously stated cost, and sometimes with the cleanup cheaper than the original as well as cleaner), the cleanup becomes part of the economy, and life goes on. (Imagine life without toilets and sewers, with people dumping their poop out the windows in the morning into the street the way we used to do…) (check out this clip, Toilets and the Smart Grid, from Earth: The Operators’ Manual, https://www.youtube.com/watch?v=KJqDQ41m_KI

The twin energy problems—finding replacements for the finite fossil fuels, and doing so before the world is changed too much in bad ways—are arguably the biggest environmental problems we have ever faced, but they can be solved. Because of the huge size, the solutions will take longer, and more inventions will be required than for the ozone hole or DDT or lead in gasoline. The scholarship is clear that speeding up our solutions will make us better off.

The big picture on climate and energy is a little too big for our course—indeed, Dr. Alley has been the primary author of a different course on this topic, wrote a book on it, made a three-hour PBS miniseries, and has given more than 1000 public talks on the subject.  Here, as Enrichment, we’ll give you some of the highlights, emphasizing the ability of people to solve problems, discussing how important energy is to our well-being and the great value we have gotten from fossil fuels, discussing how the CO2 from fossil-fuel burning is changing the climate, exploring some of the threats if continue with our current energy system, presenting the strong reasons why changing sooner rather than later will make us better off, looking at some of the solutions we could adopt, and saying a few words about communicating these issues.  The biggest picture is that, if we seriously work to solve these problems, most people who view this material should live long enough to see us build a sustainable energy system, powering everyone essentially forever, and giving us a larger economy with more jobs, improved health and greater national security, in a cleaner and more ethical world.  And that’s good news!  

A few of the images are not in the public domain but are used here following many public presentations, with attribution for non-profit educational purposes under fair use.  Most of the images are in the public domain, and many (including all of the penguins, which are included mostly to lighten the mood) were taken by Richard or Cindy Alley.   

Video 1: The Value of Optimism on Climate and Energy (2:50 minutes)

Video 2: The Value of Energy (13:58 minutes)

Video 3: The Problem of Human-Caused Climate Change (12:01 minutes)

Video 4: The Dangers of Not Changing our Energy Systems (6:39 minutes)

Video 5: The Benefits of Changing our Energy System (6:39 minutes)

Video 6: Some of the Possible Solutions (8:53 minutes)

Video 7: A Few Thoughts on Communications (7:48 minutes)

Rollin' to the Future

We really are throwing wads of money at people to get energy from oil wells that really are starting to run dry, and burning oil really does make carbon dioxide that really does have a warming influence on the climate. If we keep doing what we're doing, we have high scientific confidence that the fossil fuels will run out, but not before their CO₂ and other problems damages a lot of things on the planet. The long-term solution is highly likely to involve the sun, through photovoltaics, or wind, or possibly waves and geothermal and others. Fossil fuels are just stored energy from the sun—think of them as a great battery, charged up over a few hundred million years, that we are discharging over a few hundred years, and we can already see the bulb on the flashlight starting to dim. Creedence Clearwater Revival watched the "big wheels keep on turning" in the John Fogerty song Proud Mary; in this parody, we review the ways to keep the big wheels turn without making our lives a lot harder.

Jedediah Was a Spotted Owl

Climate changes driven by fossil-fuel burning may trigger extinctions and reduce biodiversity. But, if we cut down forests and burn trees rather than burning fossil fuels, extinctions may occur that way, too. Most of the logging in the Pacific Northwest is for lumber rather than for fuel, but the trees are cut down just the same. Hoyt Axton wrote Joy to the World (Jeremiah was a Bullfrog), Three Dog Night made it famous, and countless DJs have used it to get the wedding party lurching about the dance floor at the reception. In this parody, we visit the raptor center at Penn State's Shaver's Creek Environmental Center, to discuss the impacts of deforestation on spotted owls, and the general issues of biodiversity.

Chaos and Phil the Groundhog (and weather, climate and global warming)

Many people, including US senators, have offered the opinion that our inability to forecast weather more than a week or two in advance means that we cannot forecast climate years ahead. This seems sensible, but is actually really wrong. And, anyone who understands the game of Wheel of Fortune knows why. Here’s a musical explanation, prepared for Groundhog Day 2015, when Dr. Alley was inducted into the Punxsutawney Weather Discovery Center Hall of Fame.

Review Module Requirements

You have reached the end of Module 12! Double-check the list of requirements on the Welcome to Module 12 page and the Course Calendar to be sure you have completed all the activities required for this module.

Comments or Questions?

If you have any questions, send an email via Canvas, to ALL the Teachers and TAs. To do this, add each teacher individually in the “To” line of your email. By adding all the teachers, the TAs will be included. Failure to email ALL the teachers may result in a delayed or missed response. For detailed directions on how to do this, see How to send an email in GEOSC 10 in the Important Information module.