US scientists say climate challenge ‘impossibly large’

By Tim Radford

A nine-year delay in starting systematic carbon emission reductions to stabilise the climate has made the challenge ahead almost impossibly large, US scientists say.

They argue in Environmental Research Letters that a programme of action proposed in 2004 could have been achieved with existing technology. Now it cannot.

“We need new ways to generate the vast quantities of power that we now use worldwide,” says Steve Davis of the University of California Irvine, one of the authors. “Current technologies cannot provide this much carbon-free power quickly enough or affordably enough.”

Ken Caldeira is a climate scientist working for the Carnegie Institution Department of Global Ecology at Stanford University in California.

He says: “It’s not enough to freeze greenhouse gas emissions at current levels. To prevent climate change, we need to stop dumping carbon dioxide into the atmosphere at an industrial scale.”

In 2004 two Princeton University scientists argued in Science magazine for a new way of thinking about the action that needed to be taken.

They suggested that governments could usefully divide the challenge of carbon emissions reduction into seven “wedges” – seven manageable slices, each of which involved a slow start but which would, after 50 years, reduce carbon emissions by a billion tonnes a year.

Strategies to cut each ‘wedge’ include doubling fuel efficiency of 2 billion cars from 30 to 60 mpg and eliminating tropical deforestation. (Source: Princeton University)

What that means is that each wedge, or plan of action, would after five decades account for 25 billion tonnes of carbon not released into the atmosphere.

This could be done, they said, by doubling the number of nuclear reactors worldwide, increasing automotive fuel efficiency dramatically, and so on.

But no such systematic decisions were taken; richer nations continued to burn fossil fuels, while the developing world began swiftly to catch up.

In the latest study, the scientists revisit the Princeton proposal and argue that, simply to achieve the same “business as usual” emissions level proposed in 2004, governments would now need to deploy 12 “wedges” instead of the original seven.

But to stabilise emissions at the levels they have reached in 2013 governments would need another nine wedges.

To cut emissions to the level needed to prevent climate change, they would have to deploy a further 10 – a grand total of 31 such wedges to stabilise the world’s climate by reducing carbon emissions to almost zero.

“The original study showed that we could have solved a large part of the problem with existing technologies,” says Caldeira. “But solving the whole problem now requires new technologies deployed at a massive scale.”

This article was produced by the Climate News Network

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