The White House called Tuesday for urgent action to combat climate change, as it released a study on the impact of global warming across the United States and key sectors of the US economy.
The four-year survey warned of serious threats to homes and infrastructure and industry in the face of extreme weather events.
President Barack Obama vowed during his victorious 2008 presidential campaign to make the United States a leader in tackling climate change and the "security threat" it poses.
But he has failed to convince Congress to take significant action during his subsequent years in office.
As part of a new push on the issue this week, Obama was to give televised interviews with various meteorologists Tuesday to discuss the findings of the third US National Climate Assessment.
Hundreds of the nation's best climate scientists and technical experts—from both the private and public sectors—worked on the report, which examines the impact of climate change today and makes forecasts for the next century.
The researchers warned of drought in the state of California, prairie fires in Oklahoma and rising ocean levels on the East Coast, particularly in Florida, most of them caused by humans.
Sea level rise is also eating away at low-lying areas in places like Mississippi.
In the Southeast and Caribbean regions, home to more than 80 million people and some of the nation's fastest-growing metropolitan areas, "sea level rise combines with other climate-related impacts and existing pressures such as land subsidence, causing significant economic and ecological implications."
The report cited a locally-sponsored study as saying that coastal areas in Alabama, Louisiana, Mississippi and Texas could face annual losses of $23 billion by 2030, with about half of those costs related to climate change.
The impact of global warming is unevenly distributed across US territory, with spectacular effects in Alaska, which researchers said warmed twice as fast as the rest of the country.
"Arctic summer sea ice is receding faster than previously projected and is expected to virtually disappear before mid-century," the report said.
"This is altering marine ecosystems and leading to greater ship access, offshore development opportunity and increased community vulnerability to coastal erosion."
It warned that rising permafrost temperatures would cause drier landscapes, more wildfire, changes to wildlife habitat, greater infrastructure maintenance costs and the release of greenhouse gases that increase global warming.
Facilities and roads that are vital to the US economy are also under the threat of rising water levels or an increase in already reported tropical storms hitting coastal areas, the report says.
It cites in particular State Highway 1 in Louisiana, the only road linking New Orleans to Port Fourchon, a strategic oil hub. The road is "sinking, at the same time sea level is rising," resulting in more frequent and more severe flooding during high tides and storms. A 90-day shut down of this highway would cost the nation an estimated $7.8 billion.
In more general terms, climate change will increase costs for the country's transport system and its users, said the authors, who warn that major adaptation measures will be necessary to overcome this.
The report, which can be viewed at www.globalchange.gov and aims to mobilize American citizens as well as local communities, is part of Obama's sputtering efforts to address global warming, which have gone nowhere in Congress. There, Republicans control the House of Representatives.
The fight against climate change, once a high priority issue when Obama took office, was relegated to the back burner after a bill failed in Congress early in his first term, when Democrats still held both houses.
The president's Republican foes, who now hold a majority in the House of Representatives, reject new federal laws on emissions, which they say harm growth and employment.
And Democrats from states that are heavily dependent on fossil fuels, such as oil-rich Louisiana and coal-rich West Virginia, have also come out against a transition to green energy.
During his January 28 State of the Union address, Obama reiterated that climate change is real and promised unilateral action, without Congress, to promote his energy agenda.
The administration has already taken regulatory measures, in particular by introducing tougher federal emission standards for vehicles.
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