WASHINGTON — The U.S. Department of Agriculture (USDA), in cooperation with the University Corporation for Atmospheric Research and the U.S. Global Change Research Program (USGCRP), has released “The Effects of Climate Change on U.S. Ecosystems.”
The report provides a summary of findings contained in a U.S. scientific assessment project commissioned by the USGCRP and released in May 2008. New information has been added to provide additional detail on the original findings.
The report concludes that climate change is already affecting U.S. agriculture, land resources, water resources and biodiversity, and will continue to do so. The report identifies the effects climate is having and is expected to have on natural resources and ecosystems services in the U.S. over the next several decades, including:
• Although the report does not reflect the economic consequences of these effects on production, economic implications are inescapable due to the dependence of productivity on climate, both directly (through changes in temperature and precipitation) and indirectly (through the effects of climate on pest outbreaks, weed distribution, water supplies, changes the nutritional content of forage due to elevated CO2, and so on, that in turn influence production).
• Grain and oilseed crops will mature more rapidly, but increasing temperatures will heighten the risk of crop failures, particularly where precipitation decreases or becomes more variable.
• Marketable yield of horticultural crops (such as tomato, onion, and fruit) are more vulnerable to climate change than grains and oilseed crops due to the high sensitivity of their quality and appearance to climate factors.
• Livestock mortality will decrease with warmer winters but this will be more than offset by greater mortality in hotter summers. Hotter temperatures will also result in reduced productivity of livestock and dairy animals, due to changes in consumption and lower pregnancy rates.
• Weeds that can thwart agriculture production grow more rapidly under elevated atmospheric CO2, extend their range northward, and are less sensitive to herbicide applications.
• Disease and pest prevalence will escalate as a result of shorter, warmer winters, challenging crop, livestock, and forest systems.