Climate change is exacerbating global inequality, with temperature changes enriching cool countries, such as Norway and Sweden, while dragging down economic growth in tropical and equatorial countries, according to a new report released by Stanford University.
“Our results show that most of the poorest countries on Earth are considerably poorer than they would have been without global warming,” said climate scientist Noah Diffenbaugh, lead author of the study published in the Proceedings of the National Academy of Sciences.
The study found that from 1961 to 2010, global warming decreased wealth per person in the world’s poorest countries by 17 to 30 per cent. Meanwhile, the gap between the group of nations with the highest and lowest economic output per person is now approximately 25 percent larger than it would have been without climate change.
Building on previous research, the study analysed 50 years of annual temperature and GDP measurements for 165 countries to to estimate the effects of temperature fluctuations on economic growth.
“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,” co-author assistant professor Marshall Burke explained.
To account for uncertainty, the researchers calculated more than 20,000 versions of what each country’s annual economic growth rate could have been without global warming. The estimates in the paper capture the range of outcomes delivered by those thousands of different routes.
“For most countries, whether global warming has helped or hurt economic growth is pretty certain,” said Burke.
Tropical countries, in particular, tend to have temperatures far outside the ideal for economic growth. “There’s essentially no uncertainty that they’ve been harmed,” Burke said.
It’s less clear how warming has influenced growth in countries in the middle latitudes, including the United States, China and Japan. For these and other temperate-climate nations, the analysis reveals economic impacts of less than 10 percent.