Global GHG Commitments Point to 3.5ºC Warming, Not 2.7º, by 2100
Countries’ greenhouse gas reduction targets leading into the UN climate summit in Paris are sufficient to hold average global warming to 3.5ºC by 2100—enough to buy valuable time in the push for deeper reductions, but still not the 2.7ºC implied in recent reports from the UN climate secretariat.
That’s the conclusion veteran climate blogger Joe Romm of the Center for American Progress draws from analysis by Climate Interactive, contrasted with what he describes as “a very misleading news release” and report from the UN Framework Convention on Climate Change.
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The “too-cleverly worded paragraph” that has received global media coverage quotes UN Climate Secretary Christiana Figueres’ statement that the Intended Nationally Determined Contributions (INDCs) containing national climate reduction targets “have the capability of limiting the forecast temperature rise to around 2.7ºC by 2100.” Romm explains the difference between the Climate Interactive analysis and the UNFCCC announcement: while the analysis adds up the promises countries have actually made, the UN projects them into the future.
“The overwhelming majority of the pledges end by 2030,” he writes, “but most of them imply a rate of reduction in CO2 emissions between now and 2030. So, if you assume countries will commit in the future to keep reducing emissions after 2030 at the rate they did before 2030 — and make a bunch of other optimistic assumptions—you can limit warming to 2.7°C in 2100.”
Romm goes into detail on some of those assumptions, and takes the climate secretariat to task for a confusing release that misled international media. “The best we can say right now is that, if we consider the Paris climate pledges and nothing further, the earth will warm a total of 3.5°C by 2100,” he notes. “Of course, we can continue to say that keeping total warming to 2°C is super cheap because we know that is also true.”