Scientists challenge flagship study that saw 62% climate hit to GDP

A review of an April Nature paper finds data anomalies from Uzbekistan skewed results, overstating the potential economic impact among 83 countries analysed in the original study

By Ishika Mookerjee

 

Scientists have challenged the findings of a flagship study that calculated severe climate change could cut global growth by about 62 per cent this century, and which has been widely cited by policymakers and central banks.  

An analysis of a paper published last April in Nature argues that anomalies in data for Uzbekistan, one of 83 counties examined in the original study, caused the results to overstate the potential economic hit. When Uzbekistan is removed, the projected losses by 2100 are reduced to 23 per cent, in line with other similar modeling, according to the new article, published Wednesday in the same journal.

 

“We discovered that Uzbekistan was causing a problem,” said Solomon Hsiang, a professor at Stanford University and a co-author of the new analysis. “There were some numbers reported in the data that looked like they cannot be real.”

 

The original work by scientists at the Potsdam Institute for Climate Impact Research has been cited in papers by the World Bank and Organisation for Economic Co-operation and Development, and referred to in climate policy advice issued by the Network for Greening the Financial System, the group that includes more than 140 central banks and financial supervisory bodies. 

 

Authors of the original research welcome “critical scrutiny” and have revised their analysis based on that feedback, they said in a statement. They now estimate a 17 per cent decline in global economic output by mid-century, versus the 19 per cent previously predicted. 

 

After reviewing data, their projection for 2100 has been revised down to 60 per cent from 62 per cent, Leonie Wenz, who co-authored the original research, said in an interview. A key reason for the discrepancies in Uzbekistan data was related to currency conversion errors, she said.

 

Still, the authors stand by the core premise of their findings. “If you look at the broader scientific literature from economists, from climate scientists, there’s a broad consistency of agreement with regards to substantial climate damages,” lead author Maximilian Kotz said in the same interview.

 

Other recent studies have indicated some past assessments of the economic impact of global warming are too conservative. And even the revised findings of the Potsdam study show greater action is required, Hsiang said. “We still should be investing in avoiding climate change,” he said

 

Financing needs to mitigate climate change and adapt to its impacts are likely to average about $9 trillion a year by 2030 and $10 trillion annually by mid-century, according to the International Standards Organization.