The predicted “greenhouse effect,” a long-term warming of the atmosphere, can be expected to shift U.S. agriculture northward, shrink forests dramatically and cause erosion of low-lying coastal areas as large as Massachusetts, according to an unreleased report prepared by the Environmental Protection Agency.
The global warming will increase demand for air conditioning and could lower water levels in the Great Lakes, wipe out crops in the South, diminish mountain snow packs that are a source of water for California and turn some Michigan forests into grasslands, the research found.
It could cost $73 billion to $111 billion to protect developed coastal areas from the rising sea level, but a land area of 4,100 square miles to 9,200 square miles still would be lost, the study showed. The land area of Massachusetts is 7,826 square miles.
It does not appear that overall food supplies are threatened, it said.
Congress directed the EPA to conduct separate studies on the effects of the predicted warming and of what could be done about it. A copy of the conclusions was obtained by the Associated Press on Wednesday. The reports are expected to be sent to Congress in December.