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Climate change creates winners and losers. Norway is among the winners; Nigeria among the losers.
Those are the stark findings of a peer-reviewed paper by two Stanford University professors who have tried to quantify the impact of rising greenhouse gas emissions on global inequality. It was published Monday in Proceedings of the National Academy of Sciences.
Global temperatures have risen nearly 1 degree Celsius, or 1.8 degrees Fahrenheit, since the start of the industrial age, and the study was aimed at quantifying what effect that increase has had on national economies and the global wealth gap.
Poor countries lost out, while rich countries, especially those who have racked up a lot of emissions over the last 50 years, the study found, have “benefited from global warming.”
Inequality among nations, which has come down a lot in recent decades, would have declined far faster, it concluded, had climate change not been in the mix. It estimated that the gap in per capita income in the richest and poorest countries is 25 percentage points larger than it would have been without climate change.
The study relies on earlier research by Marshall Burke, an economist at Stanford. In that earlier work, he had found that when temperatures were hotter than average (for any reason), economic growth slowed in poor countries but accelerated in rich countries. That’s because the world’s richest countries are by and large already in cooler latitudes, while poor countries are disproportionately concentrated around the Equator, where even a slight increase in temperature can be devastating to crop production, human health and labor productivity.
For this latest study, Dr. Burke, along with Noah Diffenbaugh, a climate scientist, looked at more than 20 climate models to estimate how much countries have warmed since 1960 specifically because of climate change. Then, they estimated what each country’s economic performance could have been without such a temperature rise.
Most of the world’s poor countries are poorer today than they would have been had those emissions not altered the climate, while many rich countries, especially in the northern belt of the Northern Hemisphere, are richer than they would have been, the study found.
Between 1961 and 2000, climate change dampened per capita incomes in the world’s poorest countries by between 17 percent and 30 percent. Among the countries hardest hit were also some of the largest. India, the world’s second most populous country, would have been 30 percent richer without climate change, the study concluded. For Nigeria, the most populous country in Africa, that figure was 29 percent.
Norway, which is also a big oil and gas producer, fared well: It grew 34 percent richer. The authors cautioned that data on the very hottest and the very coldest countries is relatively sparse.
Countries in temperate zones, including China and the United States, did not feel much of an effect, the study said.
“If you’re a really cool country you’ve been helped a lot,” Dr. Burke said. “If you’re a really warm country, you’ve been hurt a lot. And if you’re in the middle the effects have been smaller or much more muted.”
The findings carry enormous implications for the global debate about who should bring down greenhouse gas emissions the fastest — and who should pay for the havoc they are causing, especially in poor countries. That is already one of the stickiest issues in global climate negotiations.
Dr. Burke said this study quantified the “dual benefits” that rich countries, particularly industrialized countries in the cooler latitudes of the Northern Hemisphere, had enjoyed — first being able to consume fossil fuels to grow their economies and then reaping the gains of warmer temperatures. “Other countries have not had either of those,” Dr. Burke asserted.
“They didn’t cause the problem,” he said. “They’re being harmed by it. There’s a clear equity dimension here.”
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