From longer and hotter summers to heavier downpours to more coastal flooding, the effects of human-induced climate change are already hitting every region of the United States and the U.S. economy, a government report finds.
These extreme weather events will likely only get worse, experts say. The Northeast will experience more heat waves, extreme precipitation and coastal flooding caused by storm surge. The Midwest can expect hotter weather and increased demand for water and energy. And the Southwest will suffer hotter, drier weather and more wildfires, according to the third National Climate Assessment (NCA) released by the White House today (May 6).
"Climate change is not a distant threat — it's already affecting every region of the country and economy," John Holdren, assistant to the president for science and technology and director of the Office of Science and Technology Policy, said today at a news conference. [8 Ways Global Warming Is Already Changing the World]
The report reveals how regional impacts of climate change will affect health, agriculture, energy, water and transportation, said Jerry Melillo, a scientist at the Marine Biological Laboratory in Woods Hole, Massachusetts, and chair of the National Climate Assessment and Development Advisory Committee.
"For decades, we've been connecting the dots about climate change," Melillo said at the news conference. "Now, we have connected those dots."
Every region of the country will be affected by climate change differently, and the effects are already evident, according to the report.
Coastal areas of the United States — such as Florida and New York — face threats from sea level rise. In 2000, scientists projected that sea levels would rise by 10 to 17 inches (25 to 43 centimeters) globally by 2100, said Tom Karl, director of the National Oceanic and Atmospheric Administration's National Climatic Data Center and a member of the report's federal executive team. Now, they're projecting a rise of 12 to 48 inches (30 to 122 cm), Karl said.
Throughout much of the country, heavy precipitation will become more common, the report shows. Extremely wet weather will increase by about 70 percent in the Northeast, and by about 30 to 60 percent in the Midwest and Southeast, the report also shows.
Meanwhile, the Southwest will experience more crippling drought and high temperatures, making for longer fire seasons. Major wildfires have already ravaged parts of Colorado and California in recent years, and hot, dry weather will only exacerbate these events, the report suggests. [Global Warming: Official Report Shows Climate Change is Human-Caused (Infographic)]
Experts say they hope the report's findings impress upon the public the immediacy of climate change in their communities.
"Many Americans currently perceive climate change as a threat distant in time and space," Anthony Leiserowitz, a climate scientist at Yale University, told Live Science. "This exhaustive scientific review tells us that climate change is actually here and now. Americans are already experiencing climate impacts today, and these impacts will only become more destructive in the future if we do not start taking action now to reduce the threat," Leiserowitz said.
More than 300 scientists contributed to the National Climate Assessment report, which is part of President Barack Obama's climate action plan and was reviewed by federal agencies and the public. Holdren called the new report "the loudest and clearest alarm bell to date signaling we need to take urgent action" on climate change.
The report not only explores the impacts of climate change regionally, but also provides "actionable information," experts say.
"The National Climate Assessment report will help federal agencies, states, communities and citizens understand how climate change will impact their day-to-day activities," Steve Winkelman, director of the Center for Clean Air Policy's adaptation and transportation programs, said in a statement.
Other reports, such as those issued by the Intergovernmental Panel on Climate Change (IPCC), have demonstrated the severity of human-induced climate change before now, but the NCA is the first to comprehensively explore the phenomenon's effects on every region of the United States.
"The scientific community has been sounding the alarm over climate change for decades, and the 3rd U.S. National Climate Assessment released today offers the most comprehensive scientific report to date on U.S. climate-change impacts," Energy Secretary Ernest Moniz said in a statement, adding, "we must prepare for the effects of climate change we are already seeing."
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