By Tim Radford / Climate News Network

This house in New Orleans’ 9th Ward was destroyed by Hurricane Katrina. The graffiti on the front reads: “1600 people died 4 U 2 take this photo.” (Gilbert Mercier / CC 2.0)

U.S. researchers have calculated the detailed cost of climate change for all of the 3,143 counties in the country. The outlook is bleak, and U.S. poverty is set to grow .

If global warming continues unabated, then near the end of this century the poorest third of the counties in the U.S. could suffer economic damage that could cost up to 20% of their income.

Those counties in the south and southern midwest, already poor and hot, will lose the most. Rising temperatures will also have an impact on property crime, violent crime, agriculture, energy, coastal storms and human mortality.

Every 1°C rise in average temperatures could lift death rates by 5.4 per 100,000 and could cost 1.2% of gross domestic product, according to a new study in the journal Science.

“Unmitigated climate change will be very expensive for huge regions of the United States,” said Solomon Hsiang, professor of public policy at the University of California Berkeley. “If we continue on the current path, our analysis indicates it may result in the largest transfer of wealth from the poor to the rich in the country’s history.”

And his co-author Robert Kopp, an earth and planetary scientist at Rutgers University, said: “In the absence of major efforts to reduce emissions and strengthen resilience, the Gulf Coast will take a massive hit.

“Its exposure to sea-level rise – made worse by potentially stronger hurricanes – poses a major risk to its communities. Increasingly extreme heat will drive up violent crime, slow down workers, amp up air conditioning costs, and threaten people’s lives.”

The researchers have made their estimates of detailed impact available on an interactive map. Both Professors Kopp and Hsiang have been issuing increasingly detailed warnings of the costs of climate change for years.

More frequent floods

In 2016 Professor Kopp took a long look at sea level change over the last 3,000 years to confirm the unprecedented nature of sea level rises in the 20th century, and the link with human-driven climate change.

Earlier this year he looked at coastal flood risks around the US to predict that the kind of once-in-a-decade flood observed in cities like Charleston could be 173 times more frequent if fossil fuel emissions continued under the notorious “business as usual” scenario.

Professor Hsiang has repeatedly emphasised the economic and social costs of climate change, and used statistical methods to make the connection between violence and rising temperatures.

This time the 12 researchers from seven institutions took the big data approach. They matched state-of-the-art statistical analysis with 116 climate projections for 15 different kinds of impact and ran 29,000 simulations of the U.S. national economy to measure the real world benefits and costs of climate change at the county level, in terms of farming, crime, health, energy demand, labour and the impact on coastal communities from higher temperature, changing rainfall, rising seas and intensifying hurricanes.

Poorest hit hardest

And they concluded that, although some counties in the Pacific Northwest and New England might benefit, unless greenhouse gas emissions from fossil fuel use are slowed, then the projected 3°C to 5°C warming in the last two decades of this century could have costs comparable to the Great Recession of 2008, with the cruellest impact upon the poorest.

President Donald Trump has withdrawn the U.S. from the international pact agreed in Paris in 2015 to limit greenhouse gas emissions from fossil fuels and has separately dismissed global warming driven by human action as a hoax. But the team behind the Science study do not see it that way.

“The ‘hidden costs’ of carbon dioxide emissions are no longer hidden, since now we can see them clearly in the data,” said Amir Jina, an economist at the University of Chicago.

“The emissions coming out of our cars and power plants are reshaping the American economy. Here in the Midwest, we may see agricultural losses similar to the Dustbowl of the 1930s.”

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