Here is the draft of the long-awaited defense of why we need an ultimate target of 350 ppm for atmospheric carbon dioxide, by NASA’s James Hansen et al., “Target Atmospheric CO2: Where Should Humanity Aim?” [Yes, they know we're already at 385 ppm and rising 2 ppm a year.]

The paper does suffer from one inherent analytical weakness that makes it (a tad) less dire than it appears — and some people believe the core element of this analysis is wrong (see very end of post), although I don’t.

This paper is really just a continuation of Hansen’s earlier analysis arguing that the real-world or long-term climate sensitivity of the planet to doubled CO2 [550 ppm] is 6°C — twice the short-term or fast-feedback-only climate sensitivity used by the IPCC. [You might want to read this post first since it is a bit clearer on the difference between the two sensitivities.]

The key paleoclimate finding of the article:

We infer from the Cenozoic data that CO2 was the dominant Cenozoic forcing, that CO2 was only ~450 ppm when Antarctica glaciated, and that glaciation is reversible.

That is, if we stabilize at 450 ppm (or higher) we risk returning the planet to conditions when it was largely ice free, when sea levels were higher by 70 meters — more than 200 feet!

Three years ago, Hansen (and others) argued in Science that [due to fast feedbacks], we would warm another “0.6°C without further change of atmospheric composition” [i.e. with no more CO2 emissions]. Now he’s saying “Warming ‘in the pipeline’, most due to slow feedbacks, is now about 2°C.” So the paper concludes:

An initial 350 ppm CO2 target may be achievable by phasing out coal use except where CO2 is captured and adopting agricultural and forestry practices that sequester carbon. If the present overshoot of this target CO2 is not brief, there is a possibility of seeding irreversible catastrophic effects.

The inherent weakness of the paper from a policy perspective is that even if you accept their analysis (which many will not), the authors do not know how long we can overshoot 350, which is a function of not just the duration of the overshoot, but the magnitude (i.e. how high concentrations go). They note: “The time needed for slow feedbacks to ‘kick in’ is uncertain. Current models are inadequate and no paleoclimate analogue to the rapid human-made GHG increase exists.” We are truly running a first-of-a-kind experiment on the climate.

The authors write “paleoclimate and ongoing changes, and the ocean response time, suggest that it would be foolhardy to allow CO2 to stay in the dangerous zone for centuries.” Well, of course, but centuries is a long time. The authors argue:

Humanity’s task of moderating human-caused global climate change is urgent. Ocean and ice sheet inertias provide a buffer delaying full response by centuries, but there is a danger that human-made forcings could drive the climate system beyond tipping points such that change proceeds out of our control.

That, of course, is a central point of this blog.

On the other hand, the authors make clear that reducing concentrations is not easy even if we do not key cross carbon cycle feedback tipping points. Moreover, recent analysis suggests that “if emissions were eliminated entirely, radiative forcing from atmospheric CO₂ would decrease at a rate closely matched by declining ocean heat uptake, with the result that while future warming commitment may be negligible, atmospheric temperatures may not decrease appreciably for at least 500 years.”

So I suspect the authors are right that 450 ppm is too high if maintained for even a few centuries. On the other hand, realistically, 350 ppm is simply not going to be seen again this century. The authors write:

This target [350 ppm] must be pursued on a timescale of decades, as paleoclimate and ongoing changes, and the ocean response time, suggest that it would be foolhardy to allow CO2 to stay in the dangerous zone for centuries.

The ill-defined difference between decades and centuries is key. What if we could keep the peak below 450 ppm, and start concentrations declining by 2100, which would almost certainly require near-zero if not net-negative global emissions, and then get back to near 350 ppm by, say 2150 and then even lower by 2200? Would that be good enough? As I argued in my book, I believe that with a World War II scale effort for the next few decades, we could stay below 450. My take away from this paper is that we would need to keep up that level of effort through 2100 — to get back below current levels.

The final point of the paper deserves reprinting:

Read more

Here’s a continuation of the “It’s Easy Being Green” series from the Center for American Progress:

In response to the City of Buffalo’s plan to demolish 1,000 buildings a year for the next 10 years, Michael Gainer started Buffalo ReUse in 2006. The nonprofit’s full-time crew employs hybrid deconstruction–a combination of human labor and a telescopic forklift–as an alternative to demolition. They remove and reuse building materials, including lumber, fixtures, and architectural detail. What isn’t removed is recycled, which means less material in landfills.

In its first year and a half, Buffalo ReUse has deconstructed 10 houses, diverting nearly 30 tons of debris from landfills. They’ve obtained seed funding of nearly $250,000, developed a board of directors and a growing volunteer staff, and opened a retail store to sell the reused building materials from their deconstructions.

The organization is also supporting LEED building credits for developers to encourage more “green-minded” development and accepting donations from homeowners of new or used building materials.

To promote education about their practice, Buffalo ReUse has teamed up with the Building Materials Reuse Association and is sponsoring the first Great Lakes Deconstruction Conference in Buffalo in November of this year. The conference will explore the use of deconstruction, building materials reuse, and other creative solutions to address issues unique to abandoned housing and vacant lots in Great Lakes urban centers.

– Kari M.

“Record Glacier Thinning Means No Time to Waste on Agreeing New International Climate Regime,” said the UN Environment Programme (UNEP) on Sunday.

That statement is based on the data of the World Glacier Monitoring Service (WGMS), which “has been tracking the fate of glaciers for over a century. Continuous data series of annual mass balance, expressed as thickness change, are available for 30 reference glaciers since 1980.” Here’s the mean annual specific net balance:

“The Service calculates thickening and thinning of glaciers in terms of ‘water equivalent’. The estimates for the year 2006 indicate that further shrinking took place equal to around 1.4 metres [1400 mm] of water equivalent compared to losses of half a metre in 2005.”

Prof. Dr. Wilfried Haeberli, Director of the Service said:

“The latest figures are part of what appears to be an accelerating trend with no apparent end in sight…. This continues the trend in accelerated ice loss during the past two and a half decades.”

I know what you’re thinking: “Trend? No end in sight? But Dr. Haeberli, everybody knows the globe is cooling, and the apparent warming is just the urban heat island effect plus lousy temperature-recording stations.” As Dr. Haeberli might reply, if he had Jon Stewart’s sensibility, “Damn you, 30 reference glaciers!”

Why should we care about a bunch of melting glaciers?

Read more

Many readers of Climate Progress ask me why I waste spend so much time rebutting people who post comments repeating the standard talking points of the delayer-1000s. Yes, I am aware those people can’t be convinced, but progressives are going to hear this disinformation for years to come, and so I think it is useful to see responses.

That said, most of the talking points have been well-debunked many times here as well as other places like RealClimate and Skeptical Science. So I’m not going to waste time doing that any more in the comments. I will, of course, take on new talking points — like the recent cooling nonsense (sometimes just to have some fun).

For the delayer-1000s who want to engage in a serious discussion, I would ask one of two things:

1. Answer the key question of our time: “If you were running national and global climate policy, what level of global CO2 concentrations would be your goal and how would you achieve it?” No answer (or no answer beyond “wait for new technology“) means you are a Delayer-1000, someone who is prepared to see atmospheric carbon dioxide concentrations hit 1000 ppm, which will nullify all denier talking points and end life on this planet as we know it. OR
2. Take my bet: “$1000 says the next decade is hotter than this one. I’ll give you 2-to-1 odds.” Anyone who won’t take that bet — 2-to-1 odds is a gimme for anyone who spounts most of the delayer-1000 talking points, especially the cooling nonsense — doesn’t believe what they’re saying, and that means they are spreading disinformation. I won’t waste any time in the comments section debunking people who don’t even believe what they are saying. If $1000 is too steep, give me a counter offer. I’m also happy to take more bets on the Arctic being ice free by 2020.

If you won’t do one of those two things, then you either don’t care about the next 10 billion people to walk the Earth or you don’t believe what you are saying. Either way, a response would be a waste of time.

Now, in place of a detailed rebuttal in the comments, I’ll probably just post this link. Other readers may feel free to post this link in the comments also.

EPA modeled the Climate Security Act at the request of Congress. Their model is designed to do a better job of accounting for clean technology deployment efforts (unlike the Energy Information Administration’s NEMS model, see here and here).

The two lead Sentors have a press release I’m reprinting here:

WASHINGTON — Senators Joseph Lieberman (ID-CT) and John Warner (R-VA) today thanked the U.S. Environmental Protection Agency for completing the analysis that they had requested of their Climate Security Act (S. 2191) last November. The Senate Environment and Public Works Committee favorably reported the bill on December 5, 2007. The full Senate is expected to consider the measure this June.

“EPA’s detailed analysis indicates that the US can curb global warming without sacrificing economic prosperity,” Lieberman said. “We will examine the results closely for improvements that they might suggest for the bill.”

Warner said, “I am satisfied that EPA’s analysis demonstrates what we have long known: You can control greenhouse gas emissions in a manner that leaves the economy whole and is not burdensome on consumers.”

The ADAGE (Applied Dynamic Analysis of the Global Economy) computer model used by EPA projects the economic impacts of government policies that are designed to speed advanced energy technologies to market. The Climate Security Act is such a policy. ADAGE contains detailed treatment of new technology deployment in the power sector and explicitly models the global economy.

EPA has not yet updated the ADAGE model to reflect the provisions of the energy bill enacted last year. In order to approximate the underlying impact of those provisions, however, EPA selected a “high technology reference scenario” when running the Climate Security Act through the ADAGE model. That modeling run found:

˜ The Climate Security Act’s cut in cumulative US greenhouse-gas emissions is deeper than one found earlier by EPA to be consistent with keeping global CO2 concentrations below 500 parts per million in 2100. [Slide 141] The finding assumes that other developed countries reduce their emissions by less than the US, and that the developing countries do not start making similar reductions until 2025. According to the Intergovernmental Panel on Climate Change, keeping the global concentration below 500 ppm greatly decreases the risk of severe global warming impacts in the US and elsewhere.

˜ Under the conservative assumptions described above concerning action by other nations, the Climate Security Act does not shift US greenhouse-gas emissions abroad. In EPA’s words, “no international emissions leakage occurs.” [Slide 5]

[Slides available here.]

˜ Under the same conservative assumptions, the Climate Security Act causes US exports of energy-intensive products (e.g., steel, cement) to developing nations to increase and causes US imports of energy-intensive products from developing nations to decrease. [Slide 83]

˜ Under the Climate Security Act, US gross domestic product grows by 80% from 2010 to 2030. That is just one percentage point less than the growth in the absence of the bill. [Slide 61]

Read more