Global Warming Effects Around the World

Lancaster County, PA, USA

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People (Food)

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Dairy barn in Lancaster County, Pennsylvania

Heat stress depresses milk production in cows, and warming summer temperatures are increasing the intensity and frequency of heat stress in Lancaster County, PA—the heart of the state's most productive agricultural region. Unless we act today to curb climate change, the future of dairy farming in Lancaster County is at risk.1

Key Facts

Lancaster County, PA, is home to the world's second-largest Amish settlement and the heart of Pennsylvania's most productive agricultural region.2 Warming summer temperatures are already having negative effects on dairy operations, and the future of dairy farming in Lancaster County is at risk unless we take steps to curb emissions today.

  • Dairy is the number one agricultural sector in Pennsylvania, bringing in about $1.6 billion in 2007 and producing roughly 1.2 billion gallons (4.5 billion liters) of milk annually.2,3
  • Pennsylvania's dairy industry lost more than $44 million due to heat stress in 2005.4
  • By the end of the century milk production in Lancaster County could drop by 10 to 20 percent under a high-emissions scenario.4,8

Details

Dairy is the number one agricultural sector in Pennsylvania, bringing in about $1.6 billion and producing roughly 1.2 billion gallons (4.5 billion liters) of milk annually.2,3 More than 80 percent of the Northeast's dairy production comes from Pennsylvania and New York.2

Pennsylvania's most productive agricultural region is the southeast—centered around Lancaster County, home to the world's second-largest Amish settlement. Climate change may add to the pressures on the traditional lifestyle of the Amish.2

Average annual temperatures in Pennsylvania have risen roughly 0.5°F (0.3°C) over the last century.2 Currently, Philadelphia and Harrisburg experience more than 20 days a year over 90°F on average, while much of the rest of the state experiences less than two weeks of such days.2 The optimal temperature for milk production ranges from 40°F to 75°F (4.4°C to 24°C), depending on humidity.4

In areas such as Lancaster County, warming summer temperatures are already having negative effects on dairy operations. Increasing intensity and frequency of heat stress, which depresses milk production and birthing rates in cows, is taking a huge financial toll on dairy farmers: around $2.4 billion for U.S. farmers overall in 2002 and more than $44 million for Pennsylvania farmers in 2005.4

What the Future Holds

Thermal heat index (THI) is a calculation for determining the temperature and humidity threshold at which livestock begin to suffer heat stress.5 The THI value for heat stress in dairy cattle is approximately 72.4 According to a scientific calculation for warming in the northeastern United States, the average THI value for Lancaster County and other dairy-producing areas in Pennsylvania should remain below 72 over the next few decades—whether we make significant efforts to curb heat-trapping emissions or continue along our current track.5,6,7,8

However, the choices we make today could have a dramatic impact on people's lives and livelihoods by mid-century in places like Lancaster County.4 For example, summer temperatures in Pennsylvania are projected to rise between 6°F and 14°F (3.3°C and 7.8°C) by the end of this century if our heat-trapping emissions continue to increase at current rates.4,8 Such increases are likely to push THI values to 76 by mid-century, with a resulting decline in milk production of up to 12 percent. By the end of the century milk production in Lancaster County could drop by 10 to 20 percent if current carbon pollution trends continue.4 If, on the other hand, we act now to cut our emissions, the decline in milk production could be limited to around 10 percent and confined to small areas of Pennsylvania.4,8 Some farmers may be able to implement adaptive measures such as air conditioning to curb heat stress, but increased costs reduce profitability.2

Factors such as the price of feed also affect the dairy industry and its future prospects. Although a longer growing season and increased atmospheric CO2 levels may spur increased growth in feed crops including corn, such changes in the climate are also likely to bring negative effects. Climate models project increases in heavy precipitation (especially in spring), summer droughts (which increase the cost of irrigation), and pests and weeds (with longer life cycles and new species moving northward).4,6

Credits

Endnotes

  1. Photograph courtesy of Stephen Ausmus, United States Department of Agriculture (USDA). Accessed 15 Aug 2010 at http://www.ars.usda.gov/ is/ graphics/ photos/ mar04/ k11045-13.jpg.
  2. Union of Concerned Scientists. 2008. Climate change in Pennsylvania: Impacts and solutions for the Keystone State. Cambridge, MA.
  3. Center for Dairy Excellence. 2008. Overview of Pennsylvania's dairy industry. Online at http://www.centerfordairyexcellence.org/ index.php/ pennsylvania-dairy-industry-overview.html. Accessed May 2009.
  4. Frumhoff, P.C., J.J. McCarthy, J.M. Melillo, S.C. Moser, and D.J. Wuebbles. 2007. Confronting climate change in the U.S. Northeast: Science, impacts, and solutions. Synthesis report of the Northeast Climate Impacts Assessment (NECIA). Cambridge, MA: Union of Concerned Scientists.
  5. Klinedinst, P.L., D.A. Wilhite, G.L. Hahn, and K.G. Hubbard. 1993. The potential effects of climate change on summer season dairy cattle milk production and reproduction. Climatic Change 23:21-36.
  6. 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. In: Climate change 2007: Impacts, adaptation and vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, edited by M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden, and C.E. Hanson. Cambridge University Press, 617-652.
  7. Wolfe, D.W., L. Ziska, C. Petzoldt, L. Chase, and K. Hayhoe. 2008. Projected change in climate thresholds in the northeastern United States: Implications for crops, pests, livestock, and farmers. Mitigation and Adaptation Strategies for Global Change 13:5-6.
  8. The Intergovernmental Panel on Climate Change emissions scenarios referred to in this hot spot are the high-emissions path known as A1FI and the low-emissions path known as B1.
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