WASHINGTON — A new report warns that climate change driven by human activity already is affecting the American people and economy, with more frequent and intense heat waves, heavy downpours and, in some places, floods and droughts.
A draft version of the National Climate Assessment that was released Friday warns that as the Earth continues to warm because of increasing levels of greenhouse gases in the atmosphere, the health and livelihoods of many Americans and the ecosystems that sustain the country face some frightening impacts. Sea levels are rising, scientists warn, oceans are becoming more acidic, and glaciers and Arctic sea ice are melting.
The National Climate Assessment, which is required under the Global Change Research Act of 1990, is presented to the president and Congress every four years. It’s designed to provide a thorough overview of the status of climate science and climate change impacts.
It came the same week that the National Oceanic and Atmospheric Administration said U.S. temperatures in 2012 were the highest since record-keeping began in 1895. But the draft assessment warns that human-induced climate change "means much more than just hotter weather."
The report references increases in ocean and freshwater temperatures, frost-free days and heavy downpours. There’s also more extreme weather, including more frequent and intense winter storms along the West Coast and the coast of New England. Such storms include Sandy in late October, which while not a particularly intense hurricane, exposed the sorts of problems that communities may face as sea levels rise.
"This draft report sends a warning to all of us: We must act in a comprehensive fashion to reduce carbon pollution or expose our people and communities to continuing devastation from extreme weather events and their aftermath," Sen. Barbara Boxer, D-Calif., who heads the Senate Environment and Public Works Committee, said in a statement.
Friday’s draft assessment warns that climatic shifts have affected and will continue to affect human health, water supplies, agriculture, transportation and energy. They’ll pose the greatest challenges to communities that already are facing economic or health-related problems, and to species and habitats that already face other pressures, the assessment says.
"While some changes will bring potential benefits, such as longer growing seasons, many will be disruptive to society because our institutions and infrastructure have been designed for the relatively stable climate of the past, not the changing one of the present and future," it says. "Similarly, the natural ecosystems that sustain us will be challenged by changing conditions."
Andrew Steer, the president of the World Resources Institute, an environmental research organization, called for the White House to pay attention.
"In his second term, President Obama has a chance to ensure his legacy as a leader on climate change," Steer said in a statement. "Now is the time for the administration to move forward with new standards on power plants and other actions to put America on course to a low-carbon future."
The Clean Air Task Force, a nonprofit organization that focuses on the air pollution from coal-fired power plants, sent a letter this week to the president that outlines steps his administration could take to curb carbon emissions and spur innovation in energy research.
Climate change "involves enormous uncertainties and unknowable risks, multiple and sometimes competing pathways forward, and even disagreement about what ’success’ would mean," the letter says. "Still, we know the direction we need to head: towards a society and economy with much lower emissions of greenhouse gases."
The National Climate Assessment is coordinated by the U.S. Global Change Research Program, which is made up of 13 federal agencies. It’s produced by the National Climate Assessment Development Advisory Committee, a 60-member federal committee made up of notable scientists, business leaders and other experts.
The final assessment, to be released early in 2014, will document how climate change affects regions and sectors across the United States and how society is responding to it. The public has until April 12 to comment on the draft report.