A global agreement to curb greenhouse gas emissions would prevent nearly 70,000 premature American deaths annually by the end of the century while sparing the country hundreds of billions of dollars’ worth of economic losses, according to a major government study on the cost of climate change.

Slowing the carbon build-up in the atmosphere would also prevent severe damage to a wide range of critical ecosystems, from Hawaiian coral reefs that support tourism to shellfish beds off the East Coast, said the report released by the White House on Monday.

The report, a five-year, peer-reviewed analysis that assesses the benefits of alternative strategies for dealing with climate change, concludes that every region of the country could be spared severe economic disruptions that would result if greenhouse gas concentrations continue to soar.


Picture of the dried bottom of the Los Laureles dam reservoir that supplies water for Tegucigalpa, on the outskirts of the capital, on June 2, 2015. ORLANDO SIERRA/AFP/Getty Images

“The results are quite startling and very clear,” said Environmental Protection Agency administrator Gina McCarthy, whose agency was the chief sponsor of the report. “Left unchecked, climate change affects our health, infrastructure and the outdoors we love. But more importantly the report shows that global action on climate change will save lives.”

[Global warming risks changes to ocean life unprecedented in the last 3 million years]

The report, “Climate Change in the United States: Benefits of Global Action,” seeks to measure the potential gains for Americans under an international accord to keeps global temperatures from rising by more than 2 degrees Celsius (3.6 degrees Fahrenheit) over historical averages. The study incorporates research from earlier peer-reviewed studies as well as modeling by scientists from the Energy Department’s Laboratory complex and the Massachusetts Institute of Technology and other centers.

Researchers compared what would likely happen in a business-as-usual world, in which carbon-dioxide levels in the atmosphere soar to more than 800 parts per million by the year 2100, compared to levels of about 462 parts per million expected if aggressive action is taken over the coming decades to limit greenhouse-gas pollution.

The report concludes that the effort expended in combating climate change would yield a substantial dividend for Americans, with the benefits accumulating over time.

[Americans’ exposure to heat extremes could rise six-fold by mid-century]

For example, improvements in air quality from reduced fossil-fuel emissions would lead to about 57,000 fewer premature deaths per year by 2100, the study said. Few extreme heat waves would result in 12,000 fewer deaths each year from heat-related illness, it said.

Local governments would avoid tens of billions of dollars in damage from floods and other severe-weather events, while farmers would save up to $11 billion a year in damage to crops from a combination of drought, flooding and destructive storms. Tens of millions of acres of forests would be preserved because of fewer wildfires, the report said.

“We not only have a moral obligation to act, but we also have an economic opportunity if we take smart but aggressive action to reduce gas emissions,” said Brian Deese, a special adviser to President Obama on environmental issues.

The report’s authors acknowledged that they did not attempt to factor in all of the costs related to cutting greenhouses gases, or consider potential impacts overseas. Moreover, the study does not specify a strategy for keeping global temperatures from rising by more than 2 degrees Celsius.  Diplomats from 197 countries will meet in Paris in December to try to negotiate a treaty on reducing carbon emissions, but many climate experts say the pact will likely fall short of that goal.

But McCarthy pointed to the far greater costs of inaction, saying it was important start attacking the problem now.

“It is really not too late to avoid the worst impacts of climate change,” she said.