Senate Democrats

The Cost of Inaction: The Impacts of Climate Change on Agriculture

In recent months, rising food prices and global food shortages have increased attention on the need for stable, ample, and environmentally sound agricultural production.  The demands to meet those needs are currently being strained by a range of factors, including: rising energy prices; higher farm commodity prices; the weakening value of the dollar; a steadily increasing worldwide population; weaker than expected agricultural production in poorer nations and, to some extent, the U.S. biofuels mandate. 

Considerably less attention has been given to the present and future challenges that climate change will pose for agriculture production.  Recent studies indicate that agricultural-related climate change scenarios include increased frequency of heat stress, droughts and flooding events that will reduce crop yields and livestock productivity.  Additionally, a global mean temperature increase of approximately 5.5 deg. Celsius could lead to food price increases on average of 30 percent.[1]  This Fact Sheet, the fourth in a series published by the Democratic Policy Committee, highlights the cost that inaction on climate change could have on agricultural production.

Drought

Approximately 70 percent of the population in the developing world resides in rural areas where agriculture largely supports the population.  The United Nations Food and Agriculture Organization has estimated that the livelihoods of roughly 450 million of the world’s poorest people are entirely dependent on managed ecosystem services.  Ominously, the Fourth Assessment Report released by the Intergovernmental Panel on Climate Change (IPCC) raises special concern about the impacts that drought and temperature are expected to have crop yields, the frequency of crop failures, and diseases in livestock.  In the United States, during 2007, severe drought had significant impacts across the Southeast and Great Plains, Ohio Valley, and the Great Lakes area.  The preliminary estimates of the total damage and costs associated with the drought in 2007 exceeded $5 billion.[2]

Crop yields.  By 2020, in some countries, yields from rain-fed agriculture could be reduced by up to 50 percent.  Agricultural production, including access to food, in many African countries is projected to be severely compromised.  This would further adversely affect food security and exacerbate malnutrition.[3] 

In recent years, North America has had to deal with a number of severe weather events that have raised concerns about the agriculture sector’s ability to cope with climate change.  Throughout areas in North America that produce corn and wheat, crop yields decreased by 17 percent for each 1 deg.C of warm-temperature anomaly between 1982 and 1998. [4]  The severe drought that has recently been plaguing the Southeastern United States has been particularly devastating to agricultural production in Florida.  The Florida Department of Agriculture and Consumer Services estimated in December of 2007 that the drought could cost the state up to $1 billion.  Additionally, crops that are grown around climate thresholds, like wine grapes in California, are likely to suffer decreases in both or either yields and quality, even modest warming.

Livestock.  Climate change is expected to have a particularly acute impact on livestock production in Africa.  Livestock production is expected suffer in Africa due to deteriorating rangeland quality and changes in area from rangeland to unproductive shrub land and desert.  A recent report from the World Bank on the impact that climate change would have on livestock in Africa found that “as climate warms, net income across all animals will fall, especially across beef cattle.  The fall in net income causes African farmers to reduce the number of animals on their farms.”[5]  One of the models in the report on the found that “a 2.5 deg. Celsius warming results in a 32 percent loss in expected net income and a 5 deg.C warming leads to a 70 percent loss in expected net income.”[6]  This is important because the potential loss of livestock in Africa could increase the chances for destabilizing occurrences like migration, food scarcity, and economic dislocation.

Forestry.  The growth of forests is slowing in areas that have been subjected to drought.  The radial growth of white spruce trees in Alaska, for example, has decreased over the last 90 years and semi-arid forests in the Southwest have seen its growth rates decrease since 1895.[7]  The potential deterioration of forests is critical because forests provide recreation and timber benefits that promotes tourism and economic growth for local businesses and landowners.

A recent study from Indiana University study found that climate change will increase the chances for climate anomalies like El-Nino, which contributed to the worst drought in recent recorded history in the Amazon Rainforest in 1997 and 1998.  Severe droughts caused by climate could produce an exodus of small farmers into cities that would be ill-equipped the influx of new residents.

Flooding

The potential for significant increases in sea level, heavier precipitation, and flooding pose significant risks to agriculture.  The world’s production of rice is the most notable and likely crop that would be impacted by flooding.  The loss of global rice production could have serious impacts as rice is the staple food for about three billion people and production losses could intensify political instability caused by food losses.

Crop yields.  The United Nations Food and Agricultural Organization commented in 2007 that small increases in temperatures could decrease crop yields in the Southern hemisphere.  In 2007, flooding affected approximately 20 million people in India, eight million in Bangladesh, and 300,000 in Nepal.  The United Nations Food and Agricultural Organization observed that India might lose 125 million tons of its rain-fed cereal production, equivalent to 18 percent of its total production from the floods.  World rice production must increase by about one percent every year, to meet the demand of our planet’s growing population.[8]

Heat Waves and Climate Variability 

Recent studies show an overall increase of about 70 percent in the annual number of heatwave days for the Midwestern United States by the late 21st century.  The trend of increasing heat waves are the result from a combination of general warming, which will raise temperatures more frequently above thresholds, and more frequent and intense weather patterns that produce heat waves.

Livestock.  An increase in for heatwaves would put significant thermal stress on livestock.  The Fourth Assessment Report released by the IPCC reports that this added heat stress would “put a ceiling on dairy milk yield…and that thermal challenge often results in declines in physical activity with associated declines in eating and grazing.”[9]  Cattle would be particularly impacted by increased temperatures as their primary breeding season occurs in the spring and summer months and their conception rates decline when the temperature rises above 75 degrees Fahrenheit (23.4 deg. C).

The expected increase in climate variability is also expected to have significant impacts on animal productivity.  The Fourth Assessment Report also found that the “lack of prior conditioning to weather events most often results in catastrophic losses in confined cattle feedlots with economic losses from reduced cattle performance exceeding those associated with cattle death losses by several-fold.”[10]  The United States has the largest fed-cattle industry in the world, and is the world’s largest producer of beef, primarily high-quality, grain-fed beef for domestic and export use.  The U.S. market share for beef climbed to almost 9 percent in 2007 and it is expected that meat exports were valued at more than $2.7 billion in 2007.

Pests and Diseases

Pests and animal diseases.  Rising temperatures and carbon dioxide levels continue to present agricultural challenges as they have led to a proliferation of pests and diseases.  For example, throughout Canada and the United States, earlier springs have increased insect and pest activity in some species.  Additionally, the increased likelihood of climate extremes may also increase the spread plant diseases and the chances for pest outbreaks.

The recently released report by the U.S. Climate Change Science Program on the effects of climate change on agriculture documented that “numerous studies have already documented changes in spring arrival, over-wintering, and/or geographic range of several insect and animal species due to climate change.  Disease pressure from leaf and root pathogens may increase in regions where increases in humidity and frequency of heavy rainfall events are projected, and decrease in regions projected to encounter more frequent drought.”[11]

Bark beetle.  Climate change is beginning to impact North American forests as the mountain pine beetle has thrived due to drought.  The unusually hot, dry summers and mild winters have increased beetle attacks and in 2006 about 23 million acres were affected.[12]  In Colorado, a bark beetle outbreak in 2006 was responsible for the death of approximately five million lodgepole pine trees; approximately 45 percent of the state’s lodgepole pine trees have died from the bark beetle.  The continued infestation of the bark beetle in forests would increase the chances for catastrophic forest fires which harm residents, businesses, and the ecology of the region.  Widespread forest fires also release substantial amounts of carbon dioxide into the atmosphere.

Endnotes



[1].   Easterling, W.E., P.K. Aggarwal, P. Batima, K.M. Brander, L. Erda, S.M. Howden, A. Kirilenko, J. Morton, J.-F. Soussana, J. Schmidhuber and F.N. Tubiello, 2007: Food, fibre and forest products.  Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds., Cambridge University Press, Cambridge, UK, 273-313.

[2]    National Climatic Data Center, Billion Dollar Weather, http://www.ncdc.noaa.gov/oa/reports/billionz.html

[3]    Easterling, W.E., P.K. Aggarwal, P. Batima, K.M. Brander, L. Erda, S.M. Howden, A. Kirilenko, J. Morton, J.-F. Soussana, J. Schmidhuber and F.N. Tubiello, 2007: Food, fibre and forest products.  Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds., Cambridge University Press, Cambridge, UK, 273-313.

[4]    Field, C.B., L.D. Mortsch,, M. Brklacich, D.L. Forbes, P. Kovacs, J.A. Patz, S.W. Running and M.J. Scott, 2007: North America. Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds., Cambridge University Press, Cambridge, UK, 617-652.

[5].   Mendelsohn, Robert & Seo, Sungno Niggol, 2007. "Climate change impacts on animal husbandry in Africa : a Ricardian analysis," Policy Research Working Paper Series 4261, The World Bank.

[6].   Ibid.

[7].   Field, C.B., L.D. Mortsch,, M. Brklacich, D.L. Forbes, P. Kovacs, J.A. Patz, S.W. Running and M.J. Scott, 2007: North America. Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds., Cambridge University Press, Cambridge, UK, 617-652.

[8].   BBC News, “Rice yields dip as planet warms,” June 29, 2004, http://news.bbc.co.uk/2/hi/science/nature/3841477.stm

[9].  Easterling, W.E., P.K. Aggarwal, P. Batima, K.M. Brander, L. Erda, S.M. Howden, A. Kirilenko, J. Morton, J.-F. Soussana, J. Schmidhuber and F.N. Tubiello, 2007: Food, fibre and forest products.  Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds., Cambridge University Press, Cambridge, UK, 273-313.

[10]Ibid.

[11].  Synthesis and Assessment Product 4.3, Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research, May 27, 2008.

[12].  Testimony of Dr. John A. Helms,  Professor Emeritus of Forestry University of California, Berkeley, Senate Committee on Energy and Natural Resources on Scientific Assessment of Effects of Climate Change on Wildfire, September 24, 2007

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