Brad Plumer, a writer I sincerely hope you follow on Twitter, has a new piece up about the infamous 2C “safe” limit of global warming. This is an absolute must read piece, and I hope everyone reading this site who hasn’t read it already does so.
Brad’s article is: Two degrees: How the world failed on climate change. While I won’t comment on it in detail, partially out of a desire to push you to go read it and partially because I don’t have a lot to add, I do want to chime in on three points about the overall concept of a 2C “safe” limit:
First, the basic idea that 2C of warming over pre-industrial times (or any other specific limit measured in global average temperature) is a sufficient way to specify a guideline is naive. Just as important is the rate of change, as quick change will ripple through the environment and cause much more ecological disruption than would slow change resulting in the same absolute temperature level. We could certainly define a “safe” limit so low that accelerating from pre-industrial temps to the limit would cap the rate of change, but we’ve likely already blown by that ultra-conservative limit at our current 0.8C.
Second, even ignoring the rate-of-change argument, claiming that 2C is “safe” is making an exceedingly broad and shaky claim. As I pointed out in a post on this site in late 2010 (Some perspective on 2C for the new year), there was a kind of “proto-IPCC” UN effort involving 152 committee members from 58 countries that published their findings in the book Only One Earth in 1972 that said (page 192; emphasis added):
Clearly man has had nothing to do with these vast climatic changes [moving in and out of ice ages] in the past. And from the scale of the energy systems involved, it would seem rational to suppose that he is not likely to affect them in the future. But here we encounter another fact about our planetary life: the fragility of the balances through which the natural world that we know survives. In the field of climate, the sun’s radiations, the earth’s emissions, the universal influence of the oceans, and the impact of the ice are unquestionably vast and beyond any direct influence on the part of man. But the balance between incoming and outgoing radiation, the interplay of forces which preserves the average global level of temperature appear to be so even, so precise, that only the slightest shift in the energy balance could disrupt the whole system. It takes only the smallest movement at its fulcrum to swing a seesaw out of the horizontal. It may require only a very small percentage of change in the planet’s balance of energy to modify average temperatures by 2°C. Downward, this is another ice age; upward, a return to an ice-free age. In either case, the effects are global and catastrophic.
Since 1972 we’ve learned a lot about how the systems and subsystems, the fundamental architecture, of our planet’s biosphere interact, thanks to the tireless and often unrecognized efforts of many, many researchers and scientists. And those revelations are overwhelmingly bad news, from the outbreak of pine bark beetles to quicker than expected loss of polar ice to desertification and much more. I’ve been reviewing a lot of my file archives recently, and I’m constantly running across phrases like “worse than expected” in articles reporting scientific findings. So if we figured out in 1972 — when the original Apollo moon missions were still underway — that 2C of warming was a very bad idea, what can/should we conclude about it in 2014?
Third, Brad’s article is one of the very few I’ve seen to date that said plainly and directly that there’s almost no chance we’ll remain below 2C. This is the next great cognitive boundary we’re about to breach, the widespread recognition that we’ve blown it on 2C and now have to work even harder to avoid much worse impacts from 4C or even 6C by 2100. This change in public dialog is certainly not something anyone should be happy about, except in the very narrow sense that it’s a step toward doing something about an immense problem.
I concluded a while ago that 2C was a pipe dream based on a very simple analysis: If you add up the warming that’s already happened, the warming we can expect from the already emitted CO2 that hasn’t happened yet (thanks to that whole “love is fleeting but CO2 is forever” thing I constantly harp about), and add in the warming from our emissions released during even a very aggressive decarbonization effort, we’re right on the brink of passing a commitment to over 2C of warming.
And lest anyone forget, we’re still building new and non-CCS-capable coal plants at a horrific rate. The IEA recently tweeted the fact that (from 2005 to 2012 China added 150MW of new coal-fired capacity every day). I’ll leave it as exercise for the reader to figure out the cumulative CO2 emissions from all that new capacity if it runs for the expected 40 to 60 years. And that’s not even talking about American SUVs, Indian coal, and all the other ways humanity finds to turn fossil fuels in the ground into warming CO2 in our air and acidifying CO2 in the ocean. Any belief that we’ll suddenly have an attack of enlightened self-interest and quickly decarbonize our worldwide economy assumes “facts not in evidence”, as lawyers say.
This is why I’ve been saying for a long time (in blogosphere years) that there’s basically zero doubt we’ll have to resort to one or more geoengineering technologies in the coming decades. The impacts will mount and become quite painful and expensive, including not just adaptation (e.g. building sea walls) but also disaster relief, such as rebuilding after coastal storms or aiding potentially tens of millions of climate refugees. The latest IPCC report, specifically the Working Group III portion, openly talks about large scale efforts to remove carbon from the air and permanently sequester it. I think it’s clear that once we adjust to talking about being beyond 2C of warming, the next cognitive hurdle will be talking about the inevitability of geoengineering. That’s when things will get not just more interesting than most of us imagine, but more interesting than we can imagine.