A different method of characterizing potential climate tipping points is the subject of two studies. One of the most cited metrics is temperature differences - measured in global annual averages. The 2007 IPCC Report identified 2C (3.6F) as the most likely average annual global temperature rise over climatological norms. As I've discussed many times now, the IPCC Report is already quite out of date given recent study findings of both observational and model data. Nevertheless, the 2C rise is being widely cited in subsequent studies as a tipping point that we should work to avoid.
The two new studies use man-made emitted carbon dioxide. To keep under the danger level cited above, the world has to spew less than 1.1 trillion tons of carbon dioxide in the first half of this century. That's a pretty impressive number, no? I mean, that's a huge freaking number. Well, here's the rest of the story: the world has already emitted one third of that in just nine years, according to studies published in Thursday's edition of the journal Nature. We've emitted 367 billion tons of CO2 in 9 years. Which means at maintaining current levels only, we have at most 18 more years before a potential tipping point is reached as we're locking into >2C warming by 2100. Ah, but how will we maintain current levels? Nearly every nation on Earth is dead set on increasing their emissions. Perhaps only European countries can say they're serious about trying to emit less. Their efforts to date may not satisfy every critic, but they've tried to do far more than America has. The scale at which we must act is large, indeed. Not impossible - just large.
The important message to take from these studies is the following:
President Barack Obama said he wants to cut U.S. emissions of carbon dioxide by 80 percent. That is a "good start but it's not enough to limit warming," said Bill Hare, a study co-author who is also at the Potsdam Institute. Assuming that other countries cut their per-person emission levels to match the United States, the United States has to cut its overall pollution by 90 to 95 percent to keep the world from exceeding the 1.1 trillion ton mark, Hare said.
My worry is that given Obama's 80% goal, the Cons and CorporateDems in Congress will water down any climate change legislation to come in well below that goal (yesterday's mortgage-bankruptcy vote is a good example). All the while, they're missing the big picture: 80% isn't enough; the problem is the opposite of the way the fossil fuel industry and climate change deniers present it.
On a slightly different note, the article mentions something else that is very, very important:
Stephen Schneider of Stanford University, who paints a worst case scenario for global warming in a commentary in the journal, said the studies make it seem like scientists know where there's a solid danger line for emissions, when they don't. The papers acknowledge there is a 25 percent chance the limit should be lower. Schneider said that's a pretty big risk when the consequences of being wrong are severe.
Indeed, that is a big risk. It's the biggest risk anyone and everyone on the planet is facing. How many years of inaction, weak action, or even moderate action do we have? There is a 25% chance it's less than 18. If there were a 1-in-4 chance of something catastrophic occurring in people's everyday lives unless they took action, most of us wouldn't sit idly by. Is a 25% chance too small to bet a multi-trillion dollar world economy on? Is a 25% chance too small to bet the world's ecosystems on? It is critical that these kinds of questions need to be presented to policy makers by scientists. It is critical that elected officials discuss these and many other questions. We can't afford not to act this year. The costs only skyrocket with time as needed measures become more drastic.
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