Whether you believe we are in a natural long-term warming cycle or one that is fueled by pollution, prospects are for warmer weather, less rain in most of the U.S. and more extreme weather.
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Days Above 90°F
will increase throughout the country. Parts of the South that currently have about 60 days per year with temperatures above 90°F might have 150 or more. Extreme heat waves that occur once every 20 years will occur about every other year in much of the country.
will be more severe and widespread because of increasing temperatures. In the past 50 years, they were mitigated by rising precipitation. In the future, droughts are likely to become more frequent and severe in some regions, especially the Southwest.
U.S. average temperature rising
Up 2°F in the past 50 years; still rising. Longer warm seasons; shorter, less intense cold seasons. Greater warming in summer than in winter.
In addition to crop damage caused by more severe weather and hotter, drier summers, these trends will create other challenges for farmers:
- Carbon dioxide favors unwanted plants, such as poison ivy, over crops. In addition, plants growing in higher carbon dioxide conditions tend to be less nutritious, so insects have to eat more to meet their protein requirements.
- Higher ozone levels reduce yields for soybeans, wheat, oats, green beans, peppers and some types of cotton.
- Warmer seasons create greater pressure from weeds and insects, as they don’t die off in the winter and are able to extend their reach.
Precipitation: Up 5% in the past 50 years, mostly because of heavier downpours. Northern areas will get more precipitation in winter and spring, possibly delaying planting. Summers will get drier.
Downpours: Increasing in frequency and intensity; amount of rain in downpours up 20% in the past century, mainly in the Northeast and Midwest. This trend will continue. One-in-20 year downpours will happen every four to 15 years.
All information included in this article is from the U.S. Global Change Research Program website. These projections refer to the 48 contiguous states only, a high-emissions scenario, and changes are by 2080-2099.
- January 2011