Major study on catastrophic cost of climate change retracted - but revised figures remain alarming

A highly publicised study on the catastrophic costs of climate change has been retracted, following heavy criticism of its methodology.

The economic commitment of climate change, which was published in Nature in April last year, has been accessed more than 300,000 times and was cited in a slew of publications, including Forbes and Reuters.

However, yesterday (3 December), researchers at the Potsdam Institute for Climate Impact Research (PIK) admitted that data errors had led them to slightly overstate their findings, adding that the changes are “too substantial” for a correction. It marks the sixth paper to be retracted by the journal Nature this year.

What the climate study got wrong

The study originally predicted that climate change would trigger a decrease in global income of 19 per cent by 2050. Revised analysis now puts the figure at 17 per cent.

Authors of the study also found that there was a 99 per cent chance that by midcentury it would cost more to fix damage from climate change than it would to build resilience. However, the new analysis, which has not yet been peer-reviewed, lowered that figure to 91 per cent.

The study’s most popular finding, which made global headlines last year, was that climate change would cost $38 trillion (around €32.54 trillion) a year by 2049. This has been reduced to $32 trillion (around €27.4 trillion).

Researchers say the reduced calculation is due to climate change damage being unequally distributed across the globe, with poorer regionssuffering more losses/damage in percentage terms.

“This results in lower global damages when expressed in dollar terms,” PIK says.

It also means that annual global climate damages in dollars in the middle of this century are about five times higher (instead of six times as found in the original calculation) than the abatement costs associated withlimiting global warming to 2℃.

Feeding climate deniers

The retraction appears to have opened the floodgates for criticism beyond the scope of post-peer reviews, which allow scientific records to be continually moderated for better accuracy and transparency.

On social media, Nature’s decision to pull the paper fuelled unfoundedconspiracy theories surrounding climate science, with users arguing that researchers are "completely corrupt” and that man-made climate change is a “farce” and “political scam”.

Others argued that the media had fallen silent on the retraction, despite swift coverage from the likes of AP News, the New York Times, the Wall Street Journal, and Sky News.

While it is true the study was cited by the World Bankand other financial institutions as part of climate scenarios used by policymakers, there is no evidence to suggest the findings were exaggerated to impact the market – a scenario echoed across social media.

Why was the climate study flawed?

The study used historical data to project how changes in temperature and rainfall will affect economic growth.

However, researchers have since found errors in economic data from Uzbekistan from 1995 to 1999, which hugely skewed their findings.

They also argue that their analysis had underestimated statistical uncertainty, which measures how much a sample’s results might differ from the true value of the entire population.

The authors’ revised version corrects the underlying economic data, introduces additional controls to limit the influence of data anomalies and accounts for correlations across regions.

‘The core findings hold’

PIK says it welcomes and appreciates feedback from the wider scientific community and takes “responsibility for the oversights” that led to the retraction.

However, it stands by the heart of the study, arguing that its “core findings hold” and that economic damages from climate changetill mid-century are still “substantial” and outweigh the cost of mitigation.

“They are mainly driven by temperature changes and affect regions with low incomes and low historical emissions most," the institute explains.

“These findings are broadly consistent with wider evidence on the magnitude of economic impacts from climate change and the benefits of emission reductions.”

Climate scientist Gernot Wagner, who was not involved with the research, told AP News that the thrust of PIK’s work remains the same no matter “which part of the range the true figure will be.”

“Climate change already hits home, quite literally,” Wagner adds. “Home insurance premiums across the US have already seen, in part, a doubling over the past decade alone. Rapidly accumulating climate risks will only make the numbers go up even more.”