The U.S. government's updated estimate doesn't include climate impacts such as damage from forest fires, threats from new pests and diseases, or the combined effect of sea-level rise and storm surges

LONDON (Thomson Reuters Foundation) – Climate change impacts - from more extreme droughts and floods to effects like crop losses and sea-level rise - are costing Americans $37 per tonne of carbon dioxide released into the atmosphere, according to an updated estimate by the U.S. government.

The costs come in the form of higher food prices, rising insurance bills, greater spending on healthcare and more taxpayer dollars spent on things like federal emergency relief, economists say.

But the “social cost” of climate-changing emissions, updated from $21 a tonne back in 2010, probably still substantially underestimates the true costs associated with climate change, argues Laurie Johnson, chief economist with the Natural Resources Defense Fund, a New York-based environmental advocacy group.

For instance, while the updated estimate takes into account some consequences of coastal storms, like Superstorm Sandy that struck the east coast of the United States in 2012, it does not include damage from forest fires that burned 9.2 million acres of U.S. land in 2013, nor changing threats to farms and forests from pests and diseases that are altering their ranges or surviving better in shifting weather conditions, Johnson told a teleconference on Wednesday.

The estimate also does not look at the combined impact of sea-level rise and storm surges, “which are pretty much a lot of the damage from Hurricane Sandy” and other coastal problems, Johnson said.

Gernot Wagner, a senior economist with the Environmental Defense Fund, another green advocacy group, said such omissions mean the cost “can only be seen as a conservative or lower-bound estimate”.

He did praise the government’s effort to put a price on the costs associated with climate emissions, saying it was “a good job”, but stressed “more can and must be done”.

'EXPENSIVE FUTURE'

The Obama administration’s cost-of-carbon figure has been put to use in a variety of ways, including to justify energy efficiency rules put out by the Department of Energy, said Richard Revesz, director of the Institute for Policy Integrity at the New York University School of Law.

It is also expected to play into regulations being crafted to govern the building of new power plants in the United States, he said.

The experts urged the government to continue trying to bring the best and most updated climate science into the cost estimates, to help drive policy that could hold down carbon emissions and lower the costs linked with the damage they cause.

“Superstorm Sandy, summer wildfires in Colorado, and severe drought in the west have given us a glimpse into a future with climate change, and it’s expensive,” they noted in a blog.

“The government is acting wisely to estimate the cost of climate damage and should continue that work by making sure it’s got as complete an accounting as possible,” they added.

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