Days that averaged about 77 degrees (25 Celsius) ended up reducing people's income by about USD 5 a day when compared with days that were significantly cooler.
A county's average economic productivity decreases by nearly 1 percent for every degree Fahrenheit that the average daily temperature is above 59 (15 Celsius), says a National Bureau of Economic Research working paper released today.
And, the study's authors predict, if the world continues on its current path of greenhouse gas emissions, even warmer temperatures later this century will squeeze the US economy by tens of billions of dollars each year.
The paper by a pair of economists at the University of Illinois and University of California, Berkeley, has not yet been peer-reviewed but is part of work done for the nonpartisan economics research center that is widely cited for determining when the country is in and out of recessions.
More From This Section
In comments from other researchers, the new study was criticized for its methods and conclusions by some economists and policy experts but praised by others as groundbreaking.
The study tries to find common ground between the hard physical science of meteorology and the softer science of economics.
The numbers were clear, the researchers said.
"Hot temperatures are very bad for the economy," said study co-author Tatyana Deryugina, a professor of finance at the University of Illinois.
This has been seen in other studies in hotter, less developed areas such as India.
But scientists and economists often assumed it wouldn't be the case for richer countries with air conditioning, like the United States, said Hsiang, who teaches public policy.