Lancaster County, PA, USA Top Impact Other Impacts |
![]() 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.
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 HoldsThermal 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 Endnotes
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