Current CO2 concentration in the atmosphere

MIT economists (and others) throw in towel on 2C limit

Getting the price right on climate (emphasis added):

As global leaders prepare to gather for the Rio+20 sustainable development summit in Brazil next week, the International Monetary Fund (IMF) and a collection of economists from MIT and other organizations has released a report to help leaders confront the price tag associated with climate change. The publication — “Fiscal Policy to Mitigate Climate Change: A Guide for Policymakers” — details the most effective methods to reduce emissions and contain costs, namely through carbon pricing.

Until now, leaders have focused on slowing warming to 2 degrees Celsius to prevent catastrophic changes associated with climate change. Because this would mean taking drastic measures to hold emissions at about today’s levels, researchers at MIT argue that leaders should be realistic and start smaller because the time to act is quickly running out. Their research — “Emissions Pricing to Stabilize Global Climate” — is a chapter within the IMF guide.

The MIT research suggests an emissions price — organized through either a tax or cap-and-trade system — of about $20 to $40 per ton by 2020 to help the world community reach less stringent targets that would keep warming to 2.9 or 3.6 degrees Celsius.

“These less stringent targets are more realistic and reachable, and they still reduce the risk of more severe climate impacts,” Paltsev says. But, he warns, “we have never experienced such changes and do not know exactly how the Earth will respond, so the smaller the changes we make, the greater the risk of something unexpected and bad happening.”

Still, making small changes is better than not acting at all, Paltsev says, and we shouldn’t wait for technology to fix the problem for us.

“We can wait for a miracle technology, like biofuels with carbon capture and storage, to appear and become economical — allowing us to reach more stringent targets — but then we place our bets on something which may or may not materialize,” Paltsev says.

The longer the global community waits to take action, the higher the price tag could be and the less likely the world will be able to meet even less stringent targets. This could mean “unprecedented levels of damage and degradation” if current trends in production and consumption continue, United Nations Undersecretary General Achim Steiner said in a recent statement. He added, “The moment has come to put away the paralysis of indecision, acknowledge the facts and face up to the common humanity that unites all peoples.”

Well, that’s one way to deal with that pesky 2C limit — decide it’s not really a limit and that it’s OK to blow right past it to 2.9 to 3.6C.

One a slightly less snarky note, I would point out that I strongly agree with the message that even if we “can’t” keep anthropogenic warming below 2C, taking less strenuous action is still far better than zooming along a business as usual path and running up a thermal disequilibrium deficit we really don’t want our kids and grand kids to deal with.

And again, I would point out that the original 2C guideline is 2C of warming by the year 2100, with what happens after then apparently being of no concern to us back here in primitive 2012.

5 comments to MIT economists (and others) throw in towel on 2C limit

  • I’d really like to see the most up to date version of what we know about the mapping of specific temperature changes to global and regional outcomes. I guess before the next IPCC synthesis, that stuff is spread over a miasma of papers. Somewhere, there should be an easily accessible… hey, hang on, maybe I’ll google and get back to you…

  • At some point – years or decades from now – the social disruption caused by AGW will significantly decrease economic activity, leading to lower CO2 emissions. Of course it’s the most painful possible way to lower emissions, but it increasingly appears the most likely path.

  • Sasparilla

    Your prediction, pianoguy, seems quite plausible – the only problem is that by the time that occurs the Earth will have taken over producing the CO2 emissions for us (once you get it warm enough it takes over), via feedbacks that haven’t kicked in for us yet (permafrost melting, clathrates melting etc.), and at that point whether we emit less won’t matter (i.e. the ship will have sailed – which is what we are doing today).

    That other important detail when thinking about future actions and consequences with regards to CO2 emissions is that even if we stopped all human CO2 emissions tomorrow, totally – the planet would keep warming up for another 30 – 40 years because the oceans act as a big drag on the temperature achieving equilibrium.

  • Steve Bloom

    Dan, I think that’s the wrong question, and in any case hard to work with within the stated terms. While some effects, e.g. the demonstrated enhancement of East African drought due to a shift in the Walker Circulation, can be pinned to a specific regional temp change (warm pool heating in this instance), cause and effect are thousands of miles apart, and many others, such as the knock-on effects of the expansion of the tropics, can only be pinned to global temps. Then we have things like Arctic sea ice retreat with significant causation from non-temp factors in addition to remote temp forcing. The temp changes themselves have the drawback of sounding not too impressive. So I think the attribution (to whatever) ought to be mentioned, but the emphasis should be on the effects themselves. A list would be good to have, so unless you can find one perhaps we could crowd-source that at p3?

  • Not found anything yet Steve – yes, good idea. Though I’m just off to burn some serious carbon on holiday for ten days. I do want to search for good ways to visualise the distribution of risk from the tipping points Sasparilla mentions also.