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How to Pick a Climate Change Goal

Like any science, the science of climate change is subject to uncertainties. A new proposed index offers policymakers a steadier number to pin their policies to.
(Photo: Vadim Petrakov/Shutterstock)

(Photo: Vadim Petrakov/Shutterstock)

If you're not sure how something is going to work, you prepare for the worst, right?

When it comes to global warming, that might not be the best way to reason, a team of researchers argues this week in the journal Nature Climate Change. Predictions for what will happen in the future as a result of climate change will always have some uncertainty in them—but it leaves the door open for those resistant to climate mitigation policies to procrastinate, or to argue that we don't have to prepare. As an alternative, the researchers propose that countries base their policies on a new kind of index: How much current global warming is attributable to human activity. Such an index, they write, would reduce uncertainty, and allow for scientists to make updates when they obtain new data. (This proposal doesn't seem like it would've made certain American politicians more accepting of President Barack Obama's climate change plan, which he unveiled Monday to intense criticism.)

Countries could pledge to reduce carbon emissions by an amount that's proportional to how much global warming people have already created.

The research team includes climate change researchers from the University of Oxford in the United Kingdom and Victoria University of Wellington in New Zealand. In their paper, the researchers suggested countries could pledge to reduce carbon emissions by an amount that's proportional to how much global warming people have already created. Such a pledge should please a wide swath of the political spectrum, the team thinks. "Stakeholders who are convinced that future anthropogenic warming will be slower than current models predict will be reassured that the policy will 'bite' correspondingly more slowly," the researchers write, "while the converse is also true for those concerned about unexpectedly rapid warming in the future."

Could such an index have helped the popularity of Obama's Clean Power Plan, which mandates that power plants in the United States cut their carbon emissions by 32 percent (compared to their emissions in 2005) by 2030? Thirty-two percent sounds like a lot, but Vox's Brad Plumer calculated that the Clean Power Plan alone cuts the U.S.' carbon emissions by just six percent. (The Obama Administration has developed other polices that reduce carbon emissions further.) In 2009, the international Cancun Agreements called for countries to keep global warming within two degrees Celsius of pre-industrial levels. "Human-induced warming has brought us 10 percent closer to two degrees Celsius since 2009," the new index's lead author, Friederike Otto, said in a statement. By Otto's logic, that means countries should already have cut their overall carbon emissions by 10 percent in that time, an ambition that outstrips the Clean Power Plan's goal of six percent in 15 years.

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