Module 9.2: Food Production in a Changing Climate

Module 9.2: Food Production in a Changing Climate jls164

In Module 9.1, we explored the causes of global climate change, the ways that our food systems contribute to greenhouse gas emissions, and how climate variables are expected to change in different parts of the US. In this unit, we’ll consider the expected impacts of global climate change on food production.

Farmers have always had to struggle against the vagaries of the weather in their efforts to produce food for a growing population. Floods, droughts, heatwaves, hailstorms, late frosts, and windstorms have plagued farmers for centuries. However, with increased levels of CO2 in the atmosphere trapping more heat energy, farmers will face more extreme weather events, greater variability, and more extreme temperatures. Unpredictable and varied weather can lead to a domino effect through the entire food system, creating shortages and food price spikes. Farmers are developing strategies for resilience in the face of a changing climate, such as, more efficient irrigation, better soil health, and planting more resilient crop varieties.

Climate change can have both direct and indirect impacts on agricultural food production. Direct effects stem directly from changes in temperature, precipitation, and CO2 concentrations. For example, as temperatures increase in crop water demands and stresses on livestock increase. Changes in the maximum number of consecutive dry days can affect crop productivity. Increases in precipitation can increase soil erosion. Increased incidence of extreme weather events can also have direct impacts on agriculture, in the form of floods, droughts, hail and high winds.

Indirect effects of climate change include changes in weed, disease, and insect populations and distributions, which will have impacts on costs of managing pests and may increase crop losses. Increased incidence of wildfire can favor survival on invasive species. Some weeds respond well to increasing CO2 concentrations and may put greater pressure on crops.

In summary, a 2015 report on Climate Change, Global Food Security, and the U.S. Food System states that by 2050, global climate change may result in decreased crop yields, increased land area in crop production, higher food prices, and slightly reduced food production and consumption, compared to model results for 2015 with no climate change (Brown et al. 2015).

Global Effects of Climate Change

Human influences will continue to alter Earth’s climate throughout the 21st century. Current scientific understanding, supported by a large body of observational and modeling results, indicates that continued changes in the atmospheric composition will result in further increases in global average temperature, changes in precipitation patterns, rising sea level, changes in weather extremes, and continued declines in snow cover, land ice, and sea ice extent, among other effects that will affect U.S. and global agricultural systems.

While climate change effects vary among regions, among annual and perennial crops, and across livestock types, all production systems will be affected to some degree by climate change. Temperature increases coupled with more variable precipitation will reduce crop productivity and increase stress on livestock production systems. Extreme climate conditions, including dry spells, sustained droughts, and heatwaves will increasingly affect agricultural productivity and profitability. Climate change also exacerbates indirect biotic stresses on agricultural plants and animals. Changing pressures associated with weeds, diseases, and insect pests, together with potential changes in timing and coincidence of pollinator lifecycles, will affect growth and yields. When occurring in combination, climate change-driven effects may not simply be additive, but can also amplify the effects of other stresses on agroecosystems.

From Expert Stakeholder Workshop for the USDA Technical Report on Global Climate Change, Food Security, and the U.S. Food System
Brown, M., P. Backlund, R. Hauser, J. Jadin, A. Murray, P. Robinson, and M. Walsh
June 25-27, 2013, Reston, VA,

Brown, M.E., J.M. Antle, P. Backlund, E.R. Carr, W.E. Easterling, M.K. Walsh, C. Ammann, W. Attavanich, C.B. Barrett, M.F. Bellemare, V. Dancheck, C. Funk, K. Grace, J.S.I. Ingram, H. Jiang, H. Maletta, T. Mata, A. Murray, M. Ngugi, D. Ojima, B. O’Neill, and C. Tebaldi. 2015. Climate Change, Global Food Security, and the U.S. Food System. 146 pages.

Climate Variables that Affect Agriculture

Climate Variables that Affect Agriculture azs2

In the first part of this module, we looked at observed and predicted changes in temperature and precipitation. Now, we'll consider some of the impacts that changes in temperature and precipitation may have on crops. For example, the projected increase in temperature will increase the length of the frost-free season (the period between the last frost in the spring and the first frost in the fall), which corresponds to a similar increase in growing season length. Increases in frost-free season length have already been documented in the US (Figure 9.2.1). An increase in growing season length may sound like a great thing for food production, but as we'll see, that can make plants more vulnerable to late frosts and can also allow for more generations of pests per growing season, thus increasing pest pressure. The complexity of the system makes adapting to a changing climate quite challenging, but not insurmountable.

Observed changes in the frost-free season. See caption for more details.
Figure 9.2.1. Observed Changes in the Frost-free Season in1986-2015 compared to 1901-1960. The frost-free season length is the period between the last occurrence of 32°F in the spring and the first occurrence of 32°F in the fall. Increases in frost-free season length correspond to similar increases in growing season length.
Credit: National Climate Assessment, 2014.

Crops, livestock, and pests are all sensitive to temperature and precipitation, so changes in temperature and precipitation patterns can affect agricultural production. As a result, it's important to consider future projections of climate variables so that farmers and ranchers can adapt to become more resilient.

Projected changes in some key climate variables that affect agricultural productivity are shown in Figure 9.2.2. The lengthening of the frost-free or growing season and reductions in the number of frost days (days with minimum temperatures below freezing), shown in the top two maps, can have both positive and negative impacts. With higher temperatures, plants grow and mature faster, but may produce smaller fruits and grains and nutrient value may be reduced. If farmers can adapt warmer season crops and planting times to the changing growing season, they may be able to take advantage of the changing growing season.

The bottom-left map in Figure 9.2.2 shows the expected increase in the number of consecutive days with less than 0.01 inches of precipitation, which has the greatest impact in the western and southern part of the U.S. The bottom-right map shows that an increase in the number of nights with a minimum temperature higher than 98% of the minimum temperatures between 1971 and 2000 is expected throughout the U.S., with the highest increase expected to occur in the south and southeast. The increases in both consecutive dry days and hot nights are expected to have negative effects on both crop and animal production. There are plants that can be particularly vulnerable at certain stages of their development. For example, one critical period is during pollination, which is very important for the development of fruit, grain or fiber. Increasing nighttime temperatures during the fruit, grain or fiber production period can result in lower productivity and reduced quality. Farmers are already seeing these effects, for example in 2010 and 2012 in the US Corn Belt (Hatfield et al., 2014).

Some perennial crops, such as fruit trees and grape vines, require exposure to a certain number of hours at cooler temperatures (32oF to 50oF), called chilling hours, in order for flowering and fruit production to occur. As temperatures are expected to increase, the number of chilling hours decreases, which may make fruit and wine production impossible in some areas. A decrease in chilling hours has already occurred in the Central Valley of California and is projected to increase up to 80% by 2100 (Figure 9.2.3). Adaptation to reduced chilling hours could involve planting different varieties and crops that have lower chilling hour requirements. For example, cherries require more than 1,000 hours, while peaches only require 225. Shifts in the temperature regime may result in major shifts in certain crop production to new regions (Hatfield et al., 2014).

To supplement our coverage of the climate variables that affect agriculture, read p. 18, Box 4 in Advancing Global Food Security in the Face of a Changing Climate, and scroll down to the Learning Checkpoint below.

Projected Changes in Key Climate Variables Affecting Agricultural Productivity as described in text above.
Figure 9.2.2. Projected Changes in Key Climate Variables Affecting Agricultural Productivity. Changes are shown for 2070-2099 compared to 1971-2000 and projected under an emissions scenario that assumes continued increases in greenhouse gases.
Credit: National Climate Assessment, 2014.
Figure 3 – Reduced winter chilling projected for California’s Central Valley, 2050 and 2090 as described in text above.
Figure 9.2.3. Reduced winter chilling projected for California’s Central Valley, assuming that observed climate trends continue through 2050 and 2090.
Credit: National Climate Assessment, 2014.

Learning Checkpoint

What are some of the challenges that farmers will face in a changing climate?

Possible Answers:

  • increased temperatures
    • leads to increased ET - increased water needs for the same crop production and increased water needs for irrigation
    • heat stress
    • can lead to reduced crop yields
  • change in timing and intensity of rainfall
  • more extreme weather events – floods and droughts
  • increased CO2 concentrations
    • may benefit some crops and weeds
    • may negatively affect the nutritional makeup of some crops
  • shifting zones of crop production
  • changing threats from pests, disease, and invasive species
    • insects
    • weeds

In the first part of this module, we explored some maps from the National Climate Change Viewer. Discuss how the predicted changes in climate that you saw in those maps (Module 9.1 Projected Climate Changes) will likely affect farmers.

ANSWER: The NCCV shows that temperatures are predicted to increase, including max and min temperatures. Growing seasons will be longer. Increased temperatures could result in heat stress for some crops and increased yields for others. Changes in temperature may result in changing zones of crop production, so farmers may have to change the crops and crop varieties that they grow. Increasing temperatures will lead to increased evaporation and transpiration rates, reduced soil moisture and runoff. If precipitation in an area decreases, then farmers may need to find alternative irrigation water or change to lower-water use crops. In general, a hotter and drier climate will create the need for more water-efficient farm practices and crops.

Direct Effects of Climate Change on Crops

Direct Effects of Climate Change on Crops azs2

Plants, whether crops or native plant species have adapted to flourish within a range of optimal temperatures for germination, growth, and reproduction. For example, plants at the poles or in alpine regions are adapted to short summers and long, cold winters, and so thrive within a certain range of colder temperatures. Temperature plays an important role in the different biological processes that are critical to plant development. The optimum temperature varies for germination, growth, and reproduction varies and those optimum temperatures needed to occur at certain times in the plant's life cycle, or the plant's growth and development may be impaired.

Let's consider corn as an example. In order for a corn seed to germinate, the soil temperature needs to be a minimum of 50oF. Corn seed typically will not germinate if the soil is colder than about 50oF. The minimum air temperature for vegetative growth (i.e., the growth of stem, leaves, and branches) is about 46oF, but the optimum range of temperatures for vegetative growth of corn is 77-90oF. At temperatures outside of the optimal range, growth tends to decline rapidly. Many plants can withstand short periods of temperatures outside of the optimal range, but extended periods of high temperatures above the optimal range can reduce the quality and yield of annual crops and tree fruits. The optimal reproduction of corn occurs between 64 and 72oF, and reproduction begins to fail at temperatures above 95oF. Reproductive failure for most crops begins around 95oF.

Water availability is a critical factor in agricultural production. We saw in Module 4 how increased temperature leads to increased transpiration rates. High rates of transpiration can also exhaust soil water supplies resulting in drought stress. Plants respond to drought stress through a variety of mechanisms, such as wilting their leaves, but the net result of prolonged drought stress is usually reduced productivity and yield. Water deficit during certain stages of a plant's growth can result in defects, such as tougher leaves in kales, chards, and mustards. Another example, blossom end rot in tomatoes and watermelon, is caused by water stress and results in fruit that is unmarketable (Figure 9.2.4 and for more photos of blossom end rot on different vegetables, visit Blossom end rot causes and cures in garden vegetables).

In addition to water stress and impacts on plant productivity and yield, increased temperatures can have other effects on crops. High temperatures and direct sunlight can sunburn developing fruits and vegetables. Intense heat can even scald or cook fruits and vegetables while still on the plant.

Blossom end rot in tomatoes
Figure 9.2.4. Blossom-end-rot in a tomato
Credit: Scot Nelson, Creative Commons

Crop yield

A warming climate is expected to have negative impacts on crop yields. Negative impacts are already being seen in a few crops in different parts of the world. Figure 9.2.5 shows estimated impacts of climate trends on crop yields from 1980-2008, with declines exceeding 5% for corn, wheat, and soy in some parts of the world. Projections under different emissions scenarios for California's Central Valley show that wheat, cotton, and sunflower have the largest declines in yields, while rice and tomatoes are much less affected (Figure 9.2.6). Notice that there are two lines on the graphs in Figure 9.2.6 projecting crop yields into the future. The red line corresponds to temperature increases associated with a higher carbon dioxide emissions scenario. We saw in Module 9.1 that the more CO2 we emit, the more heat energy is trapped in the lower atmosphere, and therefore the warmer the temperatures. For some crops, those higher temperatures are associated with great impacts on the crop's yield.

Why are some crops affected more by observed and projected temperature increases than others? It depends on the crop, the climate in the region where the crop is being grown, and the amount of temperature increase. Consider the Activate your learning questions below to explore this more deeply.

Why do some crops see a positive yield change with increasing temperatures, such as alfalfa in Figure 9.2.6? Generally, warmer temperatures mean increased crop productivity, as long as those temperatures remain within the optimal range for that crop. If a crop is being grown in a climate that has typical temperatures at the cooler end of the plant's optimal range, than a bit of warming could increase the crop's productivity. If the temperatures increase above the optimal range or exceed the temperature that leads to reproductive failure, then crop yields will decline.

Climate change effects on crop yields bar charts as described in text above.
Figure 9.2.5. Climate change effects on crop yields
Credit: Nelson, 2014
Crop Yield Response to Warming in California’s Central Valley from 2010 to 2094 as described in caption below.
Figure 9.2.6. Crop Yield Response to Warming in California’s Central Valley. Changes in climate through this century will affect crops differently because individual species respond differently to warming. This figure is an example of the potential impacts on different crops within the same geographic region. Crop yield responses for eight crops in the Central Valley of California are projected under two emissions scenarios, one in which heat-trapping gas emissions are substantially reduced (B1) and another in which these emissions continue to grow (A2). This analysis assumes adequate water supplies (soil moisture) and nutrients are maintained while temperatures increase. The lines show five-year moving averages for the period from 2010 to 2094, with the yield changes shown as differences from the year 2009. Yield response varies among crops, with cotton, maize, wheat, and sunflower showing yield declines early in the period. Alfalfa and safflower showed no yield declines during the period. Rice and tomato do not show a yield response until the latter half of the period, with the higher emissions scenario resulting in a larger yield response.
Credit: National Climate Assessment, 2014.

Activate your learning

Inspect Figure 9.2.5 above. Which crops' yields have already been most affected by climate change, and which crops the least?

ANSWER: Corn and wheat have seen the largest yield impact. Corn yields were reduced by more than 5% in China and Brazil between 1980 and 2008 and wheat yields in Russia were affected by nearly 15% and globally more than 5%. Rice has seen the least impact with nearly no yield reduction globally.

What are some possible reasons for the difference in yield impact between corn, wheat, and rice that you see in Figure 9.2.5?

ANSWER: The temperature increase between 1980-2008 produced temperatures outside of the optimal range for vegetative growth and reproduction for corn and wheat, while rice has a warmer range of optimal temperatures. Also, the regions where the different crops are grown may have experienced different ranges of temperature increase between 1980 and 2008.

Consider the graph for Wheat in Figure 9.2.5. What is the % yield impact in Russia and United States? What could cause differences in yield impact between regions?

ANSWER: Between 1980 and 2008, Russia experienced a nearly 15% yield impact on wheat, while the US experienced a slightly positive impact on the yield of wheat. As we saw in Module 9.1, the temperature increase associated with climate change varies from place to place on the globe, with some regions warming more or less than others. It's possible that the wheat-growing regions of Russia experience greater warming from 1980-2008 that exposed their wheat crops to temperatures outside of their optimal range. In addition, some wheat may be being grown in regions where the climate is already on the borderline of being optimal for that crop. So wheat grown in regions where the climate is already near the warmer range of optimal temperatures will see declines sooner. On the other hand, climates that are near the colder side of the optimal temperatures might see an increase in yield with warming temperatures. For example, in the US, wheat is grown in North Dakota where a warming climate could increase yields as the temperatures are more optimal for more of the growing season.

Indirect Effects of Climate Change on Plants

Indirect Effects of Climate Change on Plants gar5209

Weeds, Insects, and Diseases

Warming temperatures associated with climate change will not only have an effect on crop species; increasing temperature also affects weeds, insect pests, and crop diseases. Weeds already cause about 34% of crop losses with insects causing 18% and disease 16%. Climate change has the potential to increase the large negative impact that weeds, insects, and diseases already have on our agricultural production system. Some anticipated effects include:

  • several weed species benefit more than crops from higher temperatures and increased CO2 levels
  • warmer temperatures increase insect pest success by accelerating life cycles, which reduces time spent in vulnerable life stages
  • warmer temperatures increase winter survival and promote the northward expansion of a range of insects, weeds, and pathogens
  • longer growing seasons allow pest populations to increase because more generations of pests can be produced in a single growing season
  • temperature and moisture stress associated with a warming climate leaves crops more vulnerable to disease
  • changes in disease prevalence and range will also affect livestock production

Modeling and predicting the rate of change and magnitude of the impact of weeds, insects, and disease on crops is particularly challenging because of the complexity of interactions between the different components of the system. The agricultural production system is complex and the interactions between species are dynamic. Climate change will likely complicate the management of weeds, pests, and diseases as the ranges of these species changes.

Effects on Soil Resources

The natural productive capacity of a farm or ranch system relies on a healthy soil ecosystem. Changing climate conditions, including extremes of temperature and precipitation, can damage soils. Climate change can interfere with healthy soil life processes and diminish the ecosystem services provided by the soil, such as the water holding capacity, soil carbon, and nutrients provided by the soils.

The intensity and frequency of extreme precipitation events are already increasing and is expected to continue to increase, which will increase soil erosion in the absence of conservation practices. Soil erosion occurs when rainfall exceeds the ability of the soil to absorb the water by infiltration. If the water can't infiltrate into the soil, it runs off over the surface and carries topsoil with it (Figure 9.2.7). The water and soil that runoff during extreme rainfall events are no longer available to support crop growth.

Shifts in rainfall patterns associated with climate change are projects to produce more intense rainstorms more often. For example, there has been a large increase in the number of days with heavy rainfall in Iowa (Figure 9.2.8), despite the fact that total annual precipitation in Iowa has not increased. Soil erosion from intense precipitation events also results in increased off-site sediment pollution. Maintaining some cover on the soil surface, such as crop residue, mulch, or cover crops, can help mitigate soil erosion. Better soil management practices will become even more important as the intensity and frequency of extreme precipitation increases.

Soil erosion in an agricultural field
Figure 9.2.7. Heavy rainfall can result in increased surface runoff and soil erosion.
Credit: Hatfield et al., 2014
Increasing downpours in Iowa as described in caption below.
Figure 9.2.8. Increasing Heavy Downpours in Iowa. Iowa is the nation’s top corn and soybean producing state. These crops are planted in the spring. Heavy rain can delay planting and create problems in obtaining a good stand of plants, both of which can reduce crop productivity. In Iowa soils with even modest slopes, rainfall of more than 1.25 inches in a single day leads to runoff that causes soil erosion and loss of nutrients and, under some circumstances, can lead to flooding. The figure shows the number of days per year during which more than 1.25 inches of rain fell in Des Moines, Iowa. Recent frequent occurrences of such events are consistent with the significant upward trend of heavy precipitation events documented in the Midwest
Credit: Hatfield et al., 2014

How Farmers Adapt to Climate Change

How Farmers Adapt to Climate Change azs2

Farmers have had to adapt to the conditions imposed on them by the climate of their region since the inception of agriculture, but recent human-induced climate change is throwing them some unexpected curve balls. Extreme heat, floods, droughts, hail, and windstorms are some of the direct effects. In addition, there are changes in weed species and distribution, and pest and disease pressures, on top of potentially depleted soils and water stress. Fortunately, there are many practices that farmers can adopt and changes that can be made to our agricultural production system to make the system more resilient to our changing climate.

Farmers and ranchers are already adapting to our changing climate by changing their selection of crops and the timing of their field operations. Some farmers are applying increasing amounts of pesticides to control increased pest pressure. Many of the practices typically associated with sustainable agriculture can also help increase the resilience of the agricultural system to impact of climate change, such as:

  • diversifying crop rotations
  • integrating livestock with crop production systems
  • improving soil quality
  • minimizing off-farm flows of nutrients and pesticides
  • implementing more efficient irrigation practices

The video below introduces and discusses several strategies being adopted by New York farmers to adapt to climate change. In addition, the fact sheet from Cornell University's Cooperative Extension about Farming Success in an Uncertain Climate produced by Cornell University's Cooperative Extension outlines solutions to challenges associated with floods, droughts, heat stress, insect invasions, and superweeds. Also, p. 35, Box 8 in Advancing Global Food Security in the Face of a Changing Climate outlines some existing technologies that can be a starting point for adapting to climate change.

Learning Checkpoint: How can farmers adapt to climate change?

Video: Climate Smart Farming Story: Adaptation and Agriculture (15:09)

Climate Smart Farming Story: Adaptation and Agriculture.

Dale Stein. Stein Farms, Le Roy, NY: The weather is definitely becoming more erratic and more extreme than what it had been in the past. Paul King, Six Mile Creek Vineyard, Ithaca, NY: I have that tendency, as others do that have lived a long time in the same place, to say, “Well the winters aren't as cold, we're not getting as much snow.” Rod Farrow, Lamont Fruit Farm, Waterport, NY: Certainly it's been a surprise over the last few years, how much earlier the seasons have become in general. Jessica Clark, Assistant Farm Manager, Poughkeepsie Farm Project: And I would say that it actually does seem like the season gets hotter faster. David Wolfe, Professor of Horticulture, Cornell University: We're here at one of Cornell's apple orchard research sites. New York is well known for the quality of its apples. We’re usually second or third in the US in apple production. And we got there by, farmers from over many years, really working with Cornell researchers to come up with best management practices. But of course, now we're facing, like farmers everywhere, new challenges, challenges associated with climate change. For example, I never expected when I got into this climate change research realm back in the 1990's, that one of the most important things that would come up with regards to the fruit crop growers is actually cold and frost damage in a warming world. The reason for that is that these plants can sometimes be tricked into blooming earlier with a warming winter. And we had known from looking at historical records that the apples were blooming a few days earlier than they used to. But in 2012 there was a real record breaker. The apples in the state bloomed about four weeks earlier than normal, never, never observed before. And of course, this put them into a really long period of frost risk. And sure enough, we lost close to half the crop in much of the state, millions of dollars of damage. So to deal with this sort of thing, we have to think about things like frost risk warning systems for farmers. Farmers may have to consider misting systems or wind machines for frost protection. And our apple breeders may have to think about coming up with genetic types that don't jump the gun in terms of early bloom in warm winters. So the experience of adapting to climate change may be different for each farm. But nevertheless, many of the state's leading agricultural industries, which include dairy, grapes, apples, and fresh market produce, all face new challenges, new risks, and new opportunities. When it comes to climate change and adaptation, farmers across New York all have a story to tell. Dale Stein. Stein Farms, Le Roy, New York: I'm Dale Stein, senior partner at Stein Farms in Le Roy. We milk 850 cows, work almost 3,000 acres of land. Today we've had very heavy rain all morning, they got flood watches up all over. We've seen years where a drought, where on the gravel ground you get almost no yield. We actually had two years in a row, 2011 and 2012 were too dry here, so all our forages were lower production. We feed 75 ton of feed a day, so about 4 tractor-trailer loads of feed a day. We ended up, by the end of 2012, running out of our surplus forage. We used all that up. We end up on those years buying more grain, which increases our cost of production and lowers your profit down. But we're harvesting 1500 to 2000 ton of Triticale every May, that if I didn't have, that's extra on the same ground. If I didn't have that, we would have been in a lot worse place than we were without it. Bill Verbeten, Cornell Extension Specialist: The forage inventory shortages that we've had from extreme weather conditions in recent years, is really just a sign of things to come unfortunately. Farmers have to deal with a change in climate each and every day. And so in Extension, we really try to help farmers manage their risk. And growing a triticale forage crop, or another small grain for forage, can really give another opportunity to protect their resources over the winter, because they're more vulnerable to extreme precipitation events and losing that soil. We can protect the soil. Notice the fibrous root system. This is why this crop can hold soil. Just see how much soil, even in this couple inches of roots, that this is holding onto. Dale Stein. Stein Farms, Le Roy, New York: My standpoint, from what I've seen on this farm, Triticale works very well for us and the palatability is phenomenal, the cow's love it Bill Verbeten, Cornell Extension Specialist: So this is an awesome combination of a profitable crop that protects the environment. Dale: Baffles me why more farmers aren't using Triticale, just baffles me. Paul King, Six Mile Creek Vinyard, Ithaca, New York: I'm Paul King. I do most of the vineyard management, and most of the winemaking, and all of the distilling, here at Six Mile Creek Vineyard, and I've been here for almost 25 years. If we talk about climate change, longer growing season and a little hotter weather will ripen the fruit more dependably. There are some varieties, and I can give you two or three examples. Pinot Noir is a little fussy, Merlot for sure, Cabernet Sauvignon, and to a lesser degree, Chardonnay. I think these are varieties that will benefit. The best management option for any individual vineyard to deal with increasingly varying weather, if we talk about climate change, would be to think carefully about the varieties that they're growing. That's really the biggest management strategy, because everything else you're doing is then a little bit of, sort of a stopgap. Wind turbines help in only very specific weather conditions, where very calm conditions are set up and there's a deep gradient between the temperatures at the surface and just a few hundred feet in the air, and mixing up that layer can help a lot. But they're pretty specific weather conditions and it's a pretty costly investment. You need to grow the varieties that you can grow well, and that's what you need to do. That is especially true at Six Mile Creek, but it's also true for any of the other vineyards. Last winter was a particularly cold one and its really interesting. I think the minimum low temperature in Ithaca is still probably minus 23 degrees Fahrenheit, or so. We didn't really approach that, but what we did see here were lots of excursions to minus 14, minus 15, minus 16 degrees and that is a very, very critical temperature. You're going to get significant blood loss right around that threshold. What is that going to have on the quality and quantity of wine grapes that are grown in region? And certainly at Six Mile Creek Vineyard, we have lost most of the riesling, the fruit that we had here, as compared with our seyval, a hybrid, where we have virtually a full crop. There is a lack of name recognition of some of these hybrids. Seyval Blanc, that sounds a lot like Sauvignon Blanc, but but well is it a Sauvignon Blanc? And well it's not a Sauvignon Blanc, it's a completely different variety. It's my personal favorite. I get six ton per acre, even here. It's disease resistant. It's one of the first great varieties to ripen. It's a beautiful grape variety, it's just relatively unknown. But I think the people that I know that most enjoy wine, really like trying new wines. So there's a huge, huge outlet out there for exploring some of the new hybrids, they're great varieties. It's one of the Finger Lakes fortes. In the long run that's gonna serve to help us. Rod Farrow, Lamont Fruit Farm, Waterport, NY: I'm Rod Pharaoh, one of the owners and operators of Lamont Fruit Farm in Waterport, New York. We operate about 500 acres of apples, grow all kinds of varieties, about 29 different ones. The major varieties would be Empire Honeycrisp, Gala, Fugis, SweeTangos. We've certainly moved our bloom time forward, probably at least five to seven days, and then some years a lot more than that. How much of this we can attribute to climate change is still a little bit debatable to me personally, but there's certainly a sense that things are changing here, and that the climate is getting a little more unpredictable. And the risk of early season and early bloom seems to be greater and greater every year. The chances of a warm spell in March, an extended warm spell, seem to much larger now than they were ten years ago. I would say, in general, our farm’s definitely vulnerable to extreme weather events. It always has been. We're at the mercy of Mother Nature no matter what we do. The question is, has the frequency increased and the risk? Certainly I’d say there have been a lot of extreme instances of weather over the last thirty plus years here. We've had a number of very large hail storms, but certainly the frequency of that has been greater since 1998. One of the things that drives what you do in terms of risk management is the profitability of your business. And a profitable business can afford to do things to mitigate risk, whether that be invest in frost machines or try to choose better orchard sites, or add overhead cooling or overhead irrigation, frost protection. Through the 2000s the orchard business has generally been pretty healthy. So I certainly see an uptick in an investment in risk management. So anywhere we have reasonable sites, or good orchard sites, we've survived any frost that we've ever had, including 2012. And we look at it as a company strategy that investing in the highest possible fruit sites or orchard sites, has just as big, if not greater, economic impact then trying to mitigate a site that's going to be at risk in years when it's cold. Certainly multi-peril insurance can help in years of distinct disaster and actually make years that could be very, very bad for you, actually years that you could not necessarily thrive in, but you can at least survive through. So we're big believers in that. The strategies that are being used at the moment to lower your risk are definitely trying to try to preserve the economic viability of fruit farms and businesses in general in western New York. Not all climate change is negative. So increasing the number of heat units per season has a positive impact on what we can do for fruit size, potential yield, and return bloom tree health. So there's always gains and balances with anything. We certainly have a little bit higher risk but we also possibly have a slightly higher potential in terms of yield and value. Jessica Clark, Assistant Farm Manager, Poughkeepsie Farm Project: My name is Jessica Clark. I'm the assistant farm manager at the Poughkeepsie Farm Project. And the Poughkeepsie Farm Project is a nonprofit that has an educational mission and also a working CSA farm. We are not certified organic, but we do try to use organic practices. We notice climate change in terms of the disease susceptibility of our plants, and I've seen definitely an increase in the number of different diseases and pests that can affect us here in the Northeast. Certainly when we have very extreme weather events, and certainly when we have sort of these very strange, you know, very, either early summer, very late summers or very, very, late falls, so that it doesn't actually get to freezing until February. You know I'm sure that that extends how strong the disease pressure can be the next year, and the pest pressure. And heat stress actually can be a big factor for a lot of our Brassicas. And in general that's something you deal with as a farmer. And the changing of the seasons, spring to summer, brassicas are always going to be a challenge, but they're even more of a challenge. And they're a good indicator in terms of crops, because they do not like a lot of variability in their whether. They pretty much like the weather to always be, you know, relatively mild, not too wet, not too dry, and pretty much the same temperature all the time and that’s really just not what you get here. So we're already dealing with a change in climate, you know, what was it two years ago when we would have 80-degree weather in early March, and then go freezing in April. Crazy things can happen in a season. It's almost like predicting for unpredictability. Having that kind of reinforces the fact that we, you know, should have diversified market areas and also diversified crops. You don't have to be as diversified as the CSA because certainly that can be a little bit overboard in some areas, but certainly to rely on one crop is, you know, like playing a game of dice, like sometimes it's just not going to come up your turn. And if, certainly, if you don't have crop insurance, and even if you do have crop insurance, you know, it can be a very risky, you know, game to play. I know people who are in the orchard business in Ulster County and even their kind of going more into agro-tourism, they're going more into different crops, different specialty crops, just to have something on the side that they can rely on. You know it kind of makes one, as a farmer, more bold, to say like, “oh well, we'll just see how early we can get tomatoes if it's going to be warmer earlier”, or “we'll see how late we can have crops, you know, into the fall”. If it doesn't work, it doesn't work, but you never know and probably something else is going to fail in the meantime. I personally like to also make sure that our organic matter is high in our soils to begin with, so that it has that hummus and organic matter that's capable of holding water, as well as, as much as possible, keeping our soil covered in a cover crop, when we can. And then, even when we're tilling in that cover crop, to try and choose moments where we're not losing too much soil. Certainly we're thinking about carbon sequestration, and being able to lock in a lot of that carbon into our soil. It’s partially because it's good for the earth and partially because it's good for our plants to have that much, you know, to have a high carbon soil. You know, you come into the idea of sustainable farming knowing that you're trying to not, you know, ruin the planet and trying to, you know, make sure that you're not, um yeah, you're not messing things up to bad. David Wolfe, Professor of Horticulture, Cornell University: Well these are just some of the experiences and challenges that farmers throughout the Northeast are dealing with in adapting to climate change. But we have advantages in this region too, such as being relatively water rich. And with a longer growing season, this could open up new opportunities for new markets and new crops. Here at Cornell and Cornell's Institute of Climate Change in Agriculture, we are poised and ready to take on climate change challenges and work with our grower partners, stay one step ahead of the curve, and take advantage of any opportunities that might come our way.

Credit: Cornell Climate Smart Farming. "Climate Smart Farming Story: Adaptation and Agriculture." YouTube. September 29, 2015.

Check Your Understanding

How can frost damage increase with climate change, even if temperatures are overall warming?

ANSWER: If temperatures overall warm, some crops will bud earlier in the year as the winter warms making them more susceptible to frost damage in the event of a late frost. For example, in 2012 in the state of New York, apples bloomed four weeks earlier and close to half of the state's apple crop was lost to frost damage.

What are some ways that the risk of frost damage can be reduced in a warming climate?

ANSWER: Frost risk warning systems, misting systems, wind machines, and breeding varieties of crops that don't bloom too early in warming winters.

Why is triticale a beneficial forage crop for farmers to grow?

ANSWER: Extreme weather conditions, such as floods and droughts, can affect the harvest of forage crops. Triticale has a fibrous root system, so it can hold soil. It's a profitable crop that cows love and is more resilient to extreme weather conditions.

What is an important management strategy that farmers can use in growing grapes to work with a changing climate?

ANSWER: Think carefully about the varieties that they are growing, to make sure that they are appropriate for the climate in their region and are resilient to potential future climate changes. For example, some varieties are more cold hardy and other are more heat tolerant. Wind turbines help when the surface temperatures are very cold and there's a steep gradient, and can help prevent frost damage, but they are expensive.

What climate change impacts are the farmers in the video dealing with?

ANSWER: As our global climate changes growing seasons become hotter and some crops are susceptible to heat stress. Warm spells occur early provoking earlier bloom leaving crops vulnerable to frost risks. The frequency of extreme weather incidents has increased (e.g., floods, droughts, hail storms). Increase in the number of diseases and pests. Less predictability in length of growing season, temperature and precipitation.

What strategies are implemented by the farmers in the video to manage their farms in a changing climate?

ANSWER: Wind machines, overhead irrigation, choosing plant varieties appropriately, and siting orchards in appropriate locations. Diversified markets and diversification in crops grown increase resilience. Crop insurance decreases risk. Increase organic matter in soil and use cover crops to increase the water-holding capacity of soils and to protect soils.

References:

  • Hatfield, J., G. Takle, R. Grotjahn, P. Holden, R. C. Izaurralde, T. Mader, E. Marshall, and D. Liverman, 2014: Ch. 6: Agriculture. Climate Change Impacts in the United States: The Third National Climate Assessment, J. M. Melillo, Terese (T.C.) Richmond, and G. W. Yohe, Eds., U.S. Global Change Research Program, 150-174. doi:10.7930/J02Z13FR. On the Web: http://nca2014.globalchange.gov/report/sectors/agriculture
  • Lengnick, L. 2015. Resilient Agriculture: Cultivating Food Systems for a Changing Climate, New Society Publishers.

Climate Change in the Coupled Human-Natural System

Climate Change in the Coupled Human-Natural System azs2

We've covered quite a bit of ground in this module. We explored how human activities have led to an increase in atmospheric carbon dioxide, which in turn is increasing the surface temperature of the Earth and changing precipitation patterns. The resulting impacts on our agricultural production system are complex and potentially negative. As a result, farmers are adopting new practices and technologies to adapt to our changing climate and create more resiliency in the agricultural system.

Let's put global climate change and its interaction with our agricultural system into the Coupled Human-Natural System (CHNS) diagram that we've been using throughout the course. The development of global climate change is illustrated in the CHNS diagram in Figure 9.2.9, where the increased burning of fossil fuels within the human system results in more CO2 in the atmosphere. The response in the natural system is that more heat energy is trapped. The resulting feedback that affects the human system is that temperature increases along with all of the other climate change effects that we discuss in this module.

Diagram of Human-Natural System. See text description in link below

Figure 9.2.9. Coupled Human-Natural System diagram illustrating the development of global climate change

This loop shows the human system with an arrow labeled drivers pointing to natural system with an arrow labeled feedbacks pointing back to human system. Those four concepts are defined as follows:

Human system (human system internal interactions): human population growth, industrialization, and increased burning of fossil fuels

Drivers: increased emissions of carbon dioxide and other greenhouse gases

Natural system (natural system processes and interactions): increased greenhouse gas concentrations trap more heat energy in atmosphere

Feedbacks: increased temperatures, extreme weather events, sea level rise and precipitation variability

Credit: Human-Natural system diagram © Penn State is licensed under CC BY-NC-SA 4.0

What would be the next step in the diagram? Consider the feedbacks associated with the arrow at the bottom of the diagram that will affect the human system. What are the possible responses in the human system to these feedbacks? Our response can be categorized into two broad categories: mitigation and adaptation. We've already discussed adaptation strategies that can be implemented by farmers to adapt to a changing climate. Some examples are to change the crops grown to adapt to the higher temperatures or to install more efficient irrigation systems so that crops can be grown more efficiently.

What about mitigation? Mitigation strategies are those that are targeted at reducing the severity of climate change. One important mitigation strategy is to reduce the burning of fossil fuel, and our agricultural system is a significant contributor to greenhouse gas emissions. Shifting to use renewable energy sources and more fuel-efficient equipment are two mitigation strategies. There are other important mitigation strategies that target other greenhouse gas emissions, such as nitrous oxide from fertilizer use and methane from ruminants and some types of irrigated agriculture.

In the next couple of modules, we'll talk more about strategies to make our agricultural systems more resilient and sustainable, and you'll see how our food production can become more resilient to climate change. In addition, you'll get the opportunity to explore the project climate change impacts on your capstone region and to consider how those projected change might affect the food systems of that region.