Is there still time left to avoid 2°C of global warming? Yes, but barely.

Over the years, many nations have said they’d like to limit global warming to below 2°C (3.6°F). Past that point, the thinking goes, we’re in the realm of “dangerous” climate change — although some experts worry that even 2°C is too risky, given the changes we’ve already seen, such as the collapse of Arctic sea ice.

A stock photo of some pollution and weather in the Netherlands because, at this point, we’ve run out of creative ways to illustrate climate change. (Washington Post)

But let’s say 2°C is the goal. That looks daunting. After all, the world has already warmed about 0.8°C above pre-industrial levels. And the carbon dioxide we’ve put in the air has committed us to another 0.7°C of warming in the decades ahead. Plus, carbon emissions keep rising each year. So have we finally reached the point where it’s too late?

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Not necessarily. At least, that’s according to a new report (pdf) from the analysts at the Climate Action Tracker. They say it’s still technically feasible for the world to stay below that 2°C target. But the world would need to start revamping its energy system now. As in, today. Because with each passing year, meeting that 2°C goal becomes significantly more arduous.

Right now, the world is still off-track. When the analysts added up all existing pledges to curb emissions and plugged them into the latest climate models, they found that humans are currently on pace to heat the planet somewhere between 2.7°C and 4.2°C by the end of the century. (There’s a range because there’s still some uncertainty as to exactly how sensitive the climate is to increases in atmospheric carbon.)

Yet the Climate Action Tracker analysts aren’t ready to despair just yet. If the world’s nations could somehow trim their emissions 15 percent below present levels by 2020, and then keep cutting, then there are a number of different scenarios in which global warming could stay below 2°C.

Various strategies for how to attain this goal can be found in a big new report from the U.N. Environmental Programme. Big cuts wouldn’t be easy or cheap: Nations would need to invest in everything from improving the energy-efficiency of buildings to limiting deforestation to scaling up renewable energy and nuclear power. These efforts would cost about 1 percent of global GDP, assuming that the investments are spread out evenly over time.

http://www.washingtonpost.com/blogs/wonkblog/wp/2012/11/30/is-there-still-time-left-to-stop-global-warming-yes-but-only-barely/