The NRDC (Natural Resources Defense Council) has released an important document outlining scientific updates to the IPCC since its 2007 reports stopped collecting data at the end of 2005. To grasp the urgency of action, we also need to understand how the physical consequences of global warming have progressed since 2005 and how recent reports (on, say, carbon feedbacks) inform our analysis.

The 10-pager can be found here.

Sections of the update cover how the real world is outpacing climate models, particularly in terms of how fast glaciers are melting and sea ice thinning. For a super condensed version, see Daniel Lashof’s blog post why we’re Skating on Thin Ice in the Arctic.

There are also primer paragraphs on species impacts, smog, trees, biofuels and weather extremes, like wildfires. See a recent report, Forecast: Storm Warnings, from the Center for American Progress covering the latest science on intensifying hurricanes and how communities should be preparing for them.

Harvard economist Martin Weitzman has a new paper in which he points out that the vast majority of conventional economic analyses of climate change should carry the following label:

“WARNING: to be used ONLY for cost-benefit analysis of non-extreme climate change possibilities. NOT INTENDED to cover welfare evaluation of extreme tail possibilities, for which a complete accounting might produce ARBITRARILY DIFFERENT welfare outcomes.”

In short, if you don’t factor in plausible worst-case scenarios — and the vast majority of economic analyses don’t (this means you, William Nordhaus, and you, too, Bj¸rn Lomborg) — your analysis is useless. Pretty strong stuff for a Harvard economist!

The extreme or fat tail of the damage function (click on figure at right) represents what Weitzman calls “rare climate disasters,” although as we’ll see, they probably aren’t that rare. For Weitzman, disaster is a temperature change of > 6°C (11°F) in a century, as he explains in an earlier paper on the Stern Review on the economics of climate change:

With roughly 3% IPCC-4 probability, we will “consume” a terra incognita biosphere within a hundred years whose mass species extinctions, radical alterations of natural environments, and other extreme outdoor consequences of a different planet will have been triggered by a geologically-instantaneous temperature change that is signi…cantly larger than what separates us now from past ice ages.

Weitzman says the IPCC Fourth Assessment gives the probability of such an “extreme” temperature change as 3%, and that “to ignore or suppress the signi…cance of rare tail disasters is to ignore or suppress what economic theory is telling us loudly and clearly is potentially the most important part of the analysis” — more important than the discount rate.

For me, what is especially alarming about Weitzman’s analysis is that I have argued there is far greater chance than 3% that we will have a total warming of 6°C or more in a century or so if we don’t reverse emissions trends soon. That’s because failure to act quickly means carbon cycle feedbacks will kick in by mid-century, escalating greenhouse gas concentrations and temperatures well beyond standard IPCC projections. Put another way, if we don’t stabilize below 500 ppm of carbon dioxide emissions (we are at 380 today and were at 280 pre-industrial), we will probably soar to at least 800 ppm in a century, if not 1000 ppm or more. Losing either the permafrost or the Amazon are sufficient to take us to 1000.

Read more

The Wall Street Journal (subs. req’d) has a good article on liquid coal today. The article focuses on the push by the Coal to Liquids Coalition to convince the Pentagon to sign long-term contracts to buy the dirtiest of fuels. The WSJ presents the many reasons this makes no sense:

Read more

I’d like to propose a few new rules our political leaders might keep in mind as they figure out what their role should be in addressing global climate change.

• The first rule in treating the patient is to do no harm. As discussed previously, we must stop building conventional coal plants, inefficient buildings, gas-guzzling vehicles and other carbon-intensive projects that lock us in to heavy greenhouse gas emissions for decades to come.
• Politics may be the art of compromise, but the atmosphere isn’t negotiating. We don’t have much wiggle room to stabilize the climate. Public policy must be based on hard science not back-room deals. If politicians are afraid of lobbyists, deniers, and swift-boaters, they must take refuge in what the vast majority of climate scientists are telling us. No one said leadership would be easy. Better yet, we voters can reward good policy and make sound science sound politics.
• We need problem-solving, not problem-switching. Liquid fuels from coal help the oil import problem, but are lousy for the climate. Nuclear power is a lot cleaner than coal power, but leaves us with wastes, great new targets for terrorism, and the possibility that nuclear materials will fall into the wrong hands. All energy technologies have some drawbacks. But before we start trading one serious set of problems for others, let’s exhaust the potential of the relatively problem-free choices such as efficiency and many renewables.
• There is no silver bullet. The danger is that Congress will pass a weak carbon policy and consider the job done. It’s not that easy. Climate change is a large-scale problem that requires a portfolio of creative and comprehensive solutions — national, regional, and local. Neither a carbon tax nor cap-and-trade system is sufficient by itself.

Read more

We’ve seen the USGS predict that 2/3 of the polar bear population will be wiped out by 2050. But that analysis assumes the Arctic will still have summer ice then. The USGS acknowledges their projection is “conservative” since it is based upon an average of existing climate models and “the observed trajectory of Arctic sea ice decline appears to be underestimated by currently available models.”

In fact, the Arctic now is poised to lose all its ice by 2030 — and possibly by 2020 as I discuss below. What will happen to the polar bears?

“The survival of polar bears as a species is difficult to envisage under conditions of zero summer sea-ice cover,” concludes the 2004 Arctic Climate Impact Assessment, by leading scientists from the eight Arctic nations, including the United States. Another 2004 study, by Canadian scientists, agreed:

[G]iven the rapid pace of ecological change in the Arctic, the long generation time, and the highly specialised nature of polar bears, it is unlikely that polar bears will survive as a species if the sea ice disappears completely.

Why does the loss of sea ice threaten polar bears? The Canadian study, “Polar Bears in a Warming Climate” in Integrative and Comparative Biology, explains:

Read more