Study: climate change will hurt poorest nations most

Climate change pressures are making worse the economic gap between the world’s wealthiest nations and its poorest, according to a new study that raises questions about environmental justice between nations and the future of economic development.

“Our study makes the first accounting of exactly how much each country has been impacted economically by global warming, relative to its historical greenhouse gas contributions,” said climate scientist and lead author Noah Diffenbaugh of Stanford University in the United States.

The research, published in Proceedings of the National Academy of Sciences (PNAS) on April 22, finds that the gap between rich and poor nations is 25 percent larger now than it would have been without global warming.

The research was based on a foundation provided by a previous analysis of 50 years of annual temperature and GDP measurements in 165 countries, completed by assistant professor Marshall Burke and his co-authors and published in 2018. During the same time period between 1961 and 2010, global warming decreased per capita wealth in the world’s poorest countries by 17 to 30 percent.

Diffenbaugh, working with Burke, calculated the gap by using the prior study data along with 20 different climate research models from across the globe, while processing 20,000 possible economic outcomes for each country.

“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,” Burke said. “This means that in cold countries, a little bit of warming can help. The opposite is true in places that are already hot.”

There’s already been about 1°C in global warming, which adds up to the consequences over time.

“This is like a savings account, where small differences in the interest rate will generate large differences in the account balance over 30 or 50 years,” Diffenbaugh said in an interview for Stanford where he is the Kara J. Foundation professor in the School of Earth, Energy & Environmental Sciences.

As an example, India’s economy is now 31 percent smaller than it would have been in the absence of global warming despite the fact that the global disparities over all have improved. Brazil, Indonesia, Nigeria and Sudan also are among the most affected nations.

The opposite is true in the north – Scandinavian nations, for example – where there’s been a clear benefit to the warming. Norway, Canada, Sweden, the UK and France all have benefited. It’s less clear how warming is affecting the mid-latitudes, where countries like China and the United States are seeing less than 10 percent in impacts.

“A few of the largest economies are near the perfect temperature for economic output,” said Burke. “Global warming hasn’t pushed them off the top of the hill, and in many cases, it has pushed them toward it. But a large amount of warming in the future will push them further and further from the temperature optimum.”

In the meantime, there’s climate-finance pressure on the wealthier nations responsible for much of the world’s greenhouse gas emissions to step up their commitments. A United Nations climate summit in September 2019 will focus on what concrete plans these nations have to meet their contribution pledges and transition their economies to net-zero emissions by 2050.