This is the VOA Special English Agriculture Report.
A government report says climate change is already affecting American agriculture.
The new report is from the Climate Change Science Program, which brings together the research efforts of thirteen federal agencies. President George Bush launched the program six years ago.
Here are some of the findings by scientists:
The growing season has increased by ten to fourteen days in northern parts of the United States over the last nineteen years.
Much of the East and South now get more rain than a century ago. But the report says there is some evidence of increased drought conditions in the West and Southwest. Western states have less snow and ice on the mountains and earlier melting in the spring.
Grain and oilseed crops are likely to develop faster with increased carbon dioxide in the atmosphere. But higher temperatures will increase the risk of crop failures.
Also, horticultural crops such as tomatoes, onions and fruit are more easily affected by climate change than grains and oilseed crops.
Fewer animals will die during warmers winters, but greater numbers will die during hotter summers. And temperature extremes reduce animal production of meat or milk products.
Forests in the West, the Southwest and Alaska already have increases in fires, insect outbreaks and dead trees. But young forests on good soil will be more productive because of increased carbon dioxide levels.
At the same time, invasive plants will also grow faster and are likely to move northward. Recent research also suggests that weeds might get harder to kill with glyphosate, the most widely used plant killer in the United States.
The Department of Agriculture was the lead agency for the new report. Thirty-eight scientists from universities, national laboratories, nongovernmental organizations and federal service wrote it. They considered more than one thousand scientific publications.
The report was the strongest statement yet by the Bush administration that human activity is the main cause of climate change in the last fifty years. Carbon dioxide from the burning of oil, natural gas and coal is the main gas blamed for trapping heat in the atmosphere.
The report says warming is very likely to continue in the United States during the next twenty-five to fifty years. And it says this is so even if future greenhouse-gas emissions are reduced.
And that's the VOA Special English Agriculture Report, written by Jerilyn Watson. I'm Bob Doughty.