SAN FRANCISCO - Climate change is already affecting the United States and will threaten our future by endangering the food supply, increasing the risk of flooding and powerful hurricanes, and warming the country by as much as 10 degrees Fahrenheit by 2100 unless we make deep cuts in carbon pollution, according to a new federal report.

The draft National Climate Assessment, released for public comment this week, explains that climate change is already delivering hotter summers, more flooding and periods of extreme heat that “last longer than any living American has ever experienced.” But the report also offers five particularly disturbing predictions about climate change, according to scientists with the Center for Biological Diversity. The Center was the lead plaintiff in a lawsuit that forced the federal government to release the second national climate assessment in 2008.

“This report gives Americans a disturbing preview of a harsh future ruled by climate chaos,” said Shaye Wolf. “Our country will suffer searing heat, surging seas and terrifying storms unless we act immediately against greenhouse gas pollution. Fighting climate change should be the first thing on President Obama’s mind in the morning and his last thought before bed.”

Here are the five most disturbing findings of the draft National Climate Assessment:

1. More extreme heat: America will warm by as much as 10 degrees Fahrenheit by 2100 if carbon emissions keep rising, the report says. Greenhouse gas pollution has already roughly doubled the risk of extreme heat events (such as the scorching summer of 2011 in Texas), and major heat waves will become more intense and more common. “By the end of the century,” the report reads, “what have previously been once-in-20-year heat waves (4-day events) are projected to occur every two or three years over most of the U.S. In other words, what now seems like an extreme heat wave will become commonplace.”
2. Rising seas and more damaging extreme weather: The power of the strongest hurricanes will continue to rise, the report says, and most areas of the United States will see more frequent and more intense downpours, which can lead to harmful flooding. Sea levels could rise four feet by 2100, imperiling communities and critical infrastructure, as well as key wildlife habitat. Storm surges will become more destructive because they will ride on higher sea levels.
3. Endangered food supply: Food insecurity will increase in America and around the world. Yields of major U.S. crops are expected to decline by 2050, the report says, because of rising temperatures and growing precipitation extremes. Fishing and other marine-based food production will also suffer because ocean waters are becoming warmer and more acidic.
4. Biodiversity threatened: Many plants and animals and their habitats may be overwhelmed by climate change and other stressors. Climate change is altering some ecosystems so rapidly, the report finds, that many species “may disappear from regions where they have been prevalent, changing some regions so much that their mix of plant and animal life will become almost unrecognizable.”
5. Carbon emissions rising rapidly: Carbon pollution is still increasing, with global emissions “on track to be even higher than the high emissions scenario” analyzed in the report. America’s contribution to global emissions is about 20 percent, the report notes, and our efforts to reduce pollution are too slight to comply with international agreements to avoid dangerous climate change.

Deep and rapid greenhouse gas cuts are needed to reduce these risks. The Clean Air Act is America’s leading tool for curbing greenhouse gas pollution, and more than 45 U.S. cities have joined the Center’s Clean Air Citiescampaign urging the EPA to use the Clean Air Act to help reduce carbon in our atmosphere to no more than 350 parts per million, the level scientists say is needed to avoid catastrophic climate change.