Over the next 100 years, global warming will increase the average temperature across most of the United States by 13 degrees Fahrenheit and by 18 degrees in Alaska, the report estimates.
'Some important impacts are priceless, so the real situation is worse than the numbers can convey,' said the report's lead author, Frank Ackerman. 'But the numbers, for those impacts we can put prices on, are bad enough. Climate change is on a collision course with the U.S. economy, long before the end of the century, unless we act now.'
The Tufts researchers present two ways of estimating the costs of inaction on climate change.
A comprehensive estimate based on state-of-the-art computer modeling finds that doing nothing on global warming will cost the United States economy more than 3.6 percent of Gross Domestic Product, or GDP, by 2100. That amounts to $3.8 trillion annually in today's dollars.
On the other hand, a detailed, bottom-up analysis finds that four categories of global warming impacts - hurricane damage, real estate losses, increased energy costs and water costs - will add up to a price tag of 1.8 percent of GDP by 2100. That's almost $1.9 trillion annually in today's dollars.
Dan Lashof, director of NRDC's Climate Center, said, 'The longer we wait, the more painful and expensive the consequences will be. This report's findings are undeniable - we must act now.'
'The Climate Security Act currently in the U.S. Senate is our best opportunity to set a concrete limit on global warming pollution and provide an accompanying market that rewards companies for making real reductions,' Lashof said.
Also known as the Lieberman-Warner bill for its authors - Connecticut Independent Senator Joe Lieberman and Virginia Republican Senator John Warner - the bill was introduced last October and approved by the Senate Committee on Environment and Public Works in December 2007. It is expected to be debated in the full Senate in early June.
The bill would impose emission limits on electric utility, transportation, and manufacturing industries under a national cap-and-trade system for greenhouse gas emissions.
Polluters would mostly be allocated right-to-emit credits based on how much greenhouse gas they currently emit. The cap would get tighter over time, until by 2050, emissions would be reduced to 63 percent below 2005 levels.
Presently, greenhouse gases emitted in the United States are not subject to regulation.
'Many economic models have attempted to capture the costs of climate change for the United States,' the report states. 'For the most part, however, these analyses grossly underestimate costs by making predictions that are out of step with the scientific consensus on the daunting scope of climatic changes and the urgent need to reduce global warming emissions.'
For its model, the report's authors referred to 'The Economics of Climate Change,' a report commissioned by the British government and released in 2006, also known as the Stern Review after its author, Sir Nicholas Stern.
'We used a revised version of the Stern Review's model to provide a more accurate, comprehensive picture of the cost of global warming to the U.S. economy,' Ackerman and his colleagues explain.
Global warming is already melting sea ice and glaciers that will contribute to sea level rise. Sea level is expected to rise 23 inches in 2050 and 45 inches by 2100, with grave impacts expected for the low-lying coastal communities of the southeastern United States.
By 2100, an estimated $360 billion per year will be spent on damaged or destroyed residential coastal real estate in the United States as a result of the rising sea levels, the Tufts report shows.
The effects of climate change will also be felt in the form of more severe heat waves, hurricanes, droughts, and other erratic weather events and in their impact on our economy's bottom line.
'Curbing global warming pollution will require a substantial investment, but the cost of doing nothing will be far greater,' the authors conclude. 'Immediate action can save lives, avoid trillions of dollars of economic damage, and put us on a path to solving one of the greatest challenges of the 21st century.'