The Truth Behind That $60 Trillion Climate Change Price Tag

If all the methane off the East Siberian seafloor was released, the fallout would cost $60 trillion—a huge, staggering number.

For comparison’s sake, the world’s GDP is $70 trillion. The findings assume that 50 gigatons of methane would be released over the course of 10-to-20 years in a warming pulse.

Some climate scientists disagree with the underlying assumption. Gavin Schmidt has taken to Twitter to argue that 50 gigatons is an excessive estimate; prior warming periods didn’t show similarly large releases of methane.

On the other hand, climate scientist Dr. Michael Mann believes that “the precise magnitude of methane is an object of valid debate, but the possibility of a substantial release cannot be dismissed out of hand.” Climate modelers have underestimated Greenland sheet ice and Arctic sea ice melt, so the estimate is not outside the realm of possibility.

The authors make it clear that they’re responding to exuberant claims of $100 billion in short term benefits from a warming Arctic—if the sea ice melts, trade routes will be shortened. Neither the World Economic Forum (WEF) in its Global Risk Report, nor the International Monetary Fund in its World Economic Outlook, recognizes the potential economic threat from changes in the Arctic.

Very large numbers make us sit up and take notice, but they’re also hard to grasp. What is climate change currently costing even without that warming pulse? A NRDC report estimates that American taxpayers, through the federal government, paid $100 billion in 2012—more than the cost of education or transportation. And that doesn’t include what state and local governments, insurers, or private citizens paid. Mann estimates the global cost at $1.4 trillion per year in coastal damage, droughts, fires, floods and hurricanes.