Global economic inequality has been “exacerbated” by climate change since the 1960s, according to a new study published Monday. Cooler countries have experienced stronger economic growth as temperatures have risen while economic growth in hotter countries has been slowed by global warming.

According to a Stanford University study published in the peer-reviewed journal, Proceedings of the National Academy of Science, the gap between countries with the highest economic output per person versus those with the lowest is 25% larger than it would have been without climate change.

“By impacting poor countries so robustly, global warming has exerted a drag on long-term improvements on economic inequality,” Noah Diffenbaugh, study author and Stanford climate scientist, told ThinkProgress. And in most cases, the countries most impacted have historically contributed the least to global greenhouse gas emissions, Diffenbaugh added.

Researchers combined data on how annual temperatures impact 165 nations’ gross domestic product (GDP) with more than 20 different climate change scenarios. This allowed them to determine how much climate change has hurt or helped economies — including analyzing what economic output may have been in the absence of climate change.


They found that between 1961 and 2010, the wealth per person in the world’s poorest countries decreased between 17% to 30% as a result of rising greenhouse gas emissions.

The five countries most affected were Sudan, India, Nigeria, Indonesia, and Brazil; climate change caused the per capita GDP in these countries to drop 25 to 36%. Meanwhile, the per capita GDP of Norway, Sweden, and Canada increased 25 to 34%.

As a press release accompanying the study notes, while “economic inequality between countries has decreased in recent decades, the research suggests the gap would have narrowed faster without global warming.”

The map on the left shows countries where the GDP per capita either increased or decreased due to global warming between 1961 and 2010. The map on the right shows the same information starting from 1991, after economic data became available for more countries. (Credit: Noah Diffenbaugh and Marshall Burke)

The UK and France also saw a 9.5% and 8.5% increase in their economies as a result of warmer global temperatures, while the world’s three largest economies were minimally impacted: the United States took a small 0.2% hit in growth, Japan dropped by 1.1%, and China’s growth decreased by 1.4%. This suggests these major economies may have temperatures well-suited to economic growth but that could change as the world warms.

The study supports wider scientific findings regarding the impact of warmer temperatures on production. “[There are a] number of pathways by which the building blocks of economic activity are influenced by temperature,” Diffenbaugh said. Higher temperatures impact agricultural production, especially crops like corn, soy, and wheat. Labor productivity also declines with higher temperatures, as does cognitive performance. Meanwhile, interpersonal conflicts increase.


“The historical data clearly show that crops are more productive, people are healthier and we are more productive at work when temperatures are neither too hot nor too cold,” study co-author Marshall Burke, an assistant Earth system science professor at Stanford, said in a statement. “This means that in cold countries, a little bit of warming can help. The opposite is true in places that are already hot.”

In order to account for uncertainty in the data, the researchers ran 20,000 different versions of what each country’s economic growth could look like without climate change. “For most countries, whether global warming has helped or hurt economic growth is pretty certain,” said Burke, adding that there’s “essentially no uncertainty” that economies in tropical countries have been “harmed.”

As the study concludes, it’s been widely noted that wealthy countries have benefited disproportionately from the activities that have caused climate change, while poor countries suffer disproportionately the impacts.

“Our results show that, in addition to the direct benefits of fossil fuel use, many wealthy countries have likely been made even more wealthy by the resulting global warming,” the authors wrote. “Likewise, not only have poor countries not shared in the full benefits of energy consumption, but many have already been made poorer (in relative terms) by the energy consumption of wealthy countries.”