Estimate of the optimal tax rate on CO2 (pdf), by Lennart Stern

Summary
The optimal tax rate for a person P is defined to be the tax rate that maximises the sum of quality of life over all people.
We consider the following consequences of climate change predicted by the Stern Review:

- 400 million people more in hunger, often associated with violent conflict as it is the case in Africa, 70 million people more with malaria
– Let us ascribe the quality of life change for each of these people, where is the change in quality of life for the person P arising from a 5% change in income.

- Some estimates suggest that 200 million people may become permanently displaced by the middle of the century due to rising sea levels, more frequent floods, and more intense droughts. – Let us ascribe the quality of life changefor each of these people.

- the number of children in primary education will decrease (in the Stern Review it is said that the numbers have not been estimated): Assuming that the decrease in education levels will be proportional to the decrease in income of 5% on average for the 2 billion people living below 2 dollars per day: 100 million people less in primary education: - Let us ascribe the quality of life changefor each of these people.

-For the remaining 5830 people of the population we will take the same value of change in quality of life as the person P. (According to the Stern Review, they are on average affected by a 5% decrease in income. So this is a very conservative estimate, as the poorer people are, the more a percentage decrease in income affects their quality of life.)
From the fact that the carbon tax on the redistribution of income achieved by the tax system can be treated independently and from the assumption that possible improvements on the overall quality of life without taking into account the cost arising from climate change can be treated independently, one can show through a calculation that the optimal tax rate on CO2 is 22 as high as the on proposed in the Stern Review. This will mean that the tax on energy generated by fossil fuels, i.e. heating, transport, electricity should be about 11 times the free market price, rather than 1.5 times the free market price as it is now.

See also

Hoel M, Sterner T (2007) Discounting and relative prices. Clim Change 84:265–280

With the remarkable admission by Alan Greenspan that his “theory” of economics had a fundamental flaw,
I’ve been musing about all those emails I get from people claiming to have found a “fundamental flaw” in the “greenhouse theory”. The letters range from amusing claims that we are overlooking changes in the magnetic field, to tales about how the “weight” of carbon dioxide keeps it “near the ground”. If the writer sounds serious, then I treat them seriously, and do my best to provide a helpful reply. Often, though, I find myself in a pointless debate of the most basic, well-established physical principles. I generally cut off the discussion at this point, because I simply don’t have the time. This can result in a hostile response accusing me of “having an agenda”. Most would call me naïve for bothering to respond in the first place.

But it is possible, after all, that somewhere in that barrage of letters lies a brilliant idea that ought to be heard, and could change the course of scientific history. How to tell the difference? Well, there is a story that we tell in our family that might provide some perspective on this.

The story is about Wilhelm Reich, the controversial Freudian psychoanalyist (1897-1957). Reich was a personal acquaintance of my great uncle, William Steig, creator of Shrek, and illustrator of ones of Reich’s books. Reich thought he had made a major discovery in physics that proved the existence of a previously unrecognized form of energy, which he called “orgone energy”. He had built an “orgone energy accumulator” (basically a box whose walls were comprised of alternating layers of organic material and metal). He had done some careful experiments that demonstrated that the temperature inside the box increased above the ambient outside temperature. He made calculations that (he thought) demonstrated that the increase was greater than could be explained by thermodynamics, thereby proving the existence of an extra source of heat, which he attributed to the mysterious “orgone energy”. He sent these calculations to Albert Einstein, who graciously wrote back to him, showing where his calculations were wrong. Reich then wrote again, allegedly showing where Einstein had made an error. Einstein never wrote back. Some in my family took this as evidence that Einstein was stumped. But most people would conclude that Einstein decided he had better things to do than continue an argument that wasn’t going anywhere. This story has all the more poignancy to my family because my grandfather Henry, William’s brother, died of cancer while trying to cure himself by sitting in an orgone accumulator. I don’t of course, believe that Wilhelm Reich is responsible for my grandfather’s death. But clearly, Reich was wrong, and Einstein was right.

“But wait a minute,” you might say. “You guys at RealClimate are no Albert Einstein.” True enough. But like Einstein, we’re constantly subject to criticism from our fellow scientists. That’s what the process of peer review is all about. It’s not a perfect process, but it does provide an efficient means to separate ideas that have traction from ideas that are going nowhere. Greenspan’s pronouncements about the economy, on the other hand, were not subject to any such process. There might be a lesson in that.

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Tim Lenton won the prestigous THES award for his work on climate change tipping points published earlier this year

Tim's research into the planet's climate change tipping points is part of the GENIE project. His recent work described nine components of the climate system that are at risk of passing a tipping point.

These scenarios are co-produced with a range of organisations in Beijing and London to provide valuable insights from Chinese and international experts

This Tyndall project by Tao Wang and Jim Watson at Sussex University aims to assess alternative energy futures for China, and to evaluate the scope for mitigating China's emissions. The central question is whether China can avoid the problem of ‘carbon lock-in’ that is faced by most developed countries and characterised by dependence on carbon intensive energy systems and infrastructure that is difficult to change.

I had the opportunity to attend a three-day meeting of the Nature Conservancy last week in Vancouver. I was there with my RealClimate hat on, to offer ideas and insight on blogging in particular, and public communication of science in general.

While at the conference, I had a rare chance to see some of the inner workings of one of the world's largest and most successful environmental organizations (this was an invite-only conference, and only a handful of us were other than Nature Conservancy staff and trustees). The Nature Conservancy has a reputation of being very non-partisan, and this was abundantly evident at the conference: There were representatives present from the Shell Oil Company, from the Christian Coalition, from Environmental Defense. This broad level of buy-in of Nature Conservancy goals is perhaps not surprising, given that the main thing this organization is known for is its method of protecting land: buying it. Neither free-market boosters (if there are there any remaining) nor lefty environmentalists have any trouble with this.

What was news to me, though, was the extent to which the Nature Conservancy is also working towards influencing policy on climate change. Getting serious about climate policy is no longer a partisan issue in the U.S.: both John McCain and Barak Obama are on record for supporting cap and trade carbon markets. But one might well ask what climate policy has to do with the buy-the-land-to-protect it method of the Nature Conservancy. As I learned at the conference, there are two rationales.

First, the Nature Conservancy has a strongly science-based policy for making land-purchasing decisions. They take into account things like the minimum viable ecosystem size in determining which acquisitions will actually have lasting impact. Trouble is, for many areas, the conditions those decisions are based on may change. Areas near sea level are an obvious example. But so are the more than 10,000 acres of native tallgrass prairie that they have protected in Kansas. How much will that ecosystem change with the projected changes in precipitation in this region? Obviously, the Nature Conservancy is taking into account such projections, as best they can. But they have also decided that the risks of climate change to the world's ecosystems are too large to simply adapt to: hence their interest in helping to push governments to enact policies that will help mitigate it.

Second, it turns out that the Nature Conservancy's mission is — and has always been — much broader than is widely recognized. As they note on their mission statement page they can't possibly buy all the places they want to protect. To achieve their mission — "to preserve the plants, animals and natural communities that represent the diversity of life on Earth by protecting the lands and waters they need to survive" — they will clearly have to do something much bigger. The buzzword here is sustainability, and the nature Conservancy is now launching what they call their Campaign for a Sustainable Planet. This means a serious focus not just on direct ecosystem protection but also on sustainable development. International sustainable development goals, of course, are impossible to separate from international energy policy. And one cannot today talk about energy policy without talking about climate policy. It is therefore quite logical for the Nature Conservancy to be drawn into weighing-in on climate policy.

Now, what does this have to do with RealClimate? Well, the Nature Conservancy is interested in expanding their web-based communication toolbox. They already have a great deal of information on their web page: see for example their article on climate change adaptation, here; but they'd like to do more. And in particular, they are interested in getting more information out their from their scientists. As I already pointed out, The Nature Conservancy — which has over 700 full time scientists working for it — prides itself on being strongly science-based. So do we here at RealClimate (read our welcome page). Unlike us, whose day jobs are to produce and broadly disseminate scientific results (through teaching and publication), Nature Conservancy scientists don't necessarily publish their work. There is no doubt a lot of really interesting and important work being done that doesn't get out to many other scientists, let alone the general public. A blog, or something like it, could provide those scientists with a place to talk about their work. Hence my attendance at the meeting, to offer a bit of advice and perspective.*

Here at RealClimate, we look forward to seeing where Nature Conservancy goes with this, and wish them best success in their efforts. [Watch this space for an announcement, if and when they launch something.] For my part, I'll be especially enthusiastic if the Nature Conservancy doesn't limit itself to talking about its various projects around the world (interesting as those may be). What I'd really like to see is a site that provides their perspective on some of the more difficult — but really important — questions in the area of climate change impacts. How much danger are polar bears in, really? How will agriculture in Asian monsoon regions be affected? What are the broader effects of ocean acidification (beyond the immediate impact on coral reefs)? The Nature Conservancy won't be the last word on this — any more than RealClimate is. But their perspective, from field scientists "on the ground", could prove extremely valuable.

One additional thought. In several of the sessions I attended at the Nature Conservancy meeting, reference was made to the need to stabilize global temperature rise at no more than 2°C, and correspondingly to stabilize CO₂ levels at no greater than 450 ppm (strictly speaking, this should be 450 ppm CO₂-radiative-equivalent; there is a big difference, and it is often neglected). In each case, reference was made to the IPCC reports as the source of these numbers. Yet these numbers really don't derive from the IPCC, which (rightly) shied away from being policy prescriptive. Rather, they have their origin in a small number of documents, notably the 1995 report of the German Advisory Council on Global Change, papers related to the Exeter conference on "avoiding dangerous climate change" and in European Union Council decisions (see the 1996 and 2006 Presidency Conclusions here). Clearly, the 2°C/450 ppm numbers have completely permeated the policy-advocacy realm. Yet while they are arguably derivable from the IPCC reports, it is actually not clear to what extent the larger scientific community really believes these are the right numbers. There simply has not been a process to evaluate this that compares in depth and breadth with the IPCC. A new and much more comprehensive analysis, by a much greater group of scientists, would be valuable at this juncture. Scientists are fond of saying that they cannot summarize their projections with a small handful of simple numbers, but simple numbers are what are being discussed in policy circles. If the "right" numbers are really so low as Jim Hansen believes (see our post on this, here), then the Nature Conservancy has an even more difficult task ahead.

*[For those interested in slogging through it, there's a video of our session, here. It's not just about me. There is also some really interesting stuff from Nature Conservancy staffer Jonathon Colman and from the folks who started the conservation clearinghouse and collaboration websites www.conservationyellowpages.org and wiserearth.org, as well as a demonstration (not altogether successful) of the emerging virtual reality conferencing technology which (when it works) might help all of us travel to conferences less often. A word of advice: skip all this and instead take a look at the Keynote lectures, by far better orators than me: Mark Tercek, Nature Conservancy CEO, Jerome Ringo, Apollo Alliance President, and CARE C.O.O. Steve Hollingworth

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Many readers will remember our critique of a paper by Douglass et al on tropical tropospheric temperature trends late last year, and the discussion of the ongoing revisions to the observational datasets. Some will recall that the Douglass et al paper was trumpeted around the blogosphere as the definitive proof that models had it all wrong.

At the time, our criticism was itself criticised because our counterpoints had not been submitted to a peer-reviewed journal. However, this was a little unfair (and possibly a little disingenuous) because a group of us had in fact submitted a much better argued paper making the same principal points. Of course, the peer-review process takes much longer than writing a blog post and so it has taken until today to appear on the journal website.

The new 17-author paper (lead by Ben Santer), does a much better job of comparing the various trends in atmospheric datasets with the models and is very careful to take account of systematic uncertainties in all aspects of that comparison (unlike Douglass et al). The bottom line is that while there is remaining uncertainty in the tropical trends over the last 30 years, there is no clear discrepancy between what the models expect and the observations. There is a fact sheet available which explains the result in relatively simple terms.

Additionally, the paper explores the statistical properties of the test used by Douglass et al and finds some very odd results. Namely, that their test should nominally inadvertently reject a match 1 time out 20 (i.e. for a 5% significance), actually rejects valid comparisons 16 times out of 20! And curiously, the more data you have, the worse the test performs (figure 5 in the paper). The other aspect discussed in the paper is the importance of dealing with systematic errors in the data sets. These are essentially the same points that were made in our original blog post, but are now much more comprehensively shown. The data sources are now completely up-to-date and a much wider range of sources is addressed - not only the different satellite products, but also the different analyses of the radiosonde data.

The bottom line is best encapsulated by the summary figure 6 from the paper:

The grey band is the real 2-sigma spread of the models (while the yellow band is the spread allowed for in the flawed Douglass et al test). The other lines are the different estimates from the data. The uncertainties in both preclude any claim of some obvious discrepancy - a result you can only get by cherry-picking what data to use and erroneously downplaying the expected spread in the simulations.

Taking a slightly larger view, I think this example shows quite effectively how blogs can play a constructive role in moving science forward (something that we discussed a while ago). Given the egregiousness of the error in this particular paper (which was obvious to many people at the time), having the initial blog posting up very quickly alerted the community to the problems even if it wasn't a comprehensive analysis. The time in-between the original paper coming out and this new analysis was almost 10 months. The resulting paper is of course much better than any blog post could have been and in fact moves significantly beyond a simple rebuttal. This clearly demonstrates that there is no conflict between the peer-review process and the blogosphere. A proper paper definitely takes more time and gives generally a better result than a blog post, but the latter can get the essential points out very quickly and can save other people from wasting their time.

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The theme of this year's annual meeting of the European Meteorological Society (EMS) [European Congress on Applied Climatology (ECAC)] was adaptation to climate change. So what's more appropriate then, than hosting the meeting in Amsterdam - on a building site?

Adaption may involve changes in both building practices and in being able to forecast adverse conditions. Thus under a global warming, there is a greater need for improved seasonal forecasts to be prepared for changes in seasonal variability, a likely consequence of a global warming.

One of the more interesting talks was delivered by Tim Palmer (from the ECMWF) on 'seamless prediction'. This is one of the recent buzz words in the community. It refers to the idea of using one system to predict atmospheric conditions on time scales varying from hours to decades.

Due to historical and practical reasons, day-to-day weather forecasts tend to be performed on different systems than seasonal forecasts and climate change scenarios. Whereas the former can take the oceanic state to be approximately constant for the next few days, slow changes may have a greater impact for the latter two.

Numerical weather prediction (NWP - i.e. the daily operational weather forecast) and climatology communities have drifted apart for a while, but Palmer argued that there is a need to a convergence of the communities. He also proposed using global climate models (GCMs) the way NWP models are used for weather forecasting to test their quality. By looking at the initial part of their evolution, he reckoned it may be possible to get some idea of how good they are. Thus, he proposed a way to weigh the different GCMs up against each other. Time will show if this strategy will work.

As an illustration of how such a test may reveal the quality of the GCMs, Palmer used the model runs in the climateprediction.net project that were responsible for the very high climate sensitivities (see previous post here). These high numbers had been identified with GCMs with low convective entrainment - meaning that they mixed in less of the ambient air from the side during convection than 'normal' models. The degree of mixing is described statistically and is set by parameterizations. A comparison of NWP models using low convective entrainment with 'normal' models revealed greater imbalances in the former (one caveat was that a different model was used in this case). Thus, low values for the convective entrainment parameterization are less realistic, and hence the high climate sensitivities derived in the climateprediction.net project are therefore questionable.

One concern regarding the use of GCMs as NWP models is that the latter involve an initialization problem (predictability of the first kind) while climate modeling represent a boundary value problem (predictability of the second type; see more on this here and here). Furthermore, evaluation of the skill of weather and seasonal forecasts tend to imply regional or local scales, whereas climate modeling has focused more on the large-scale features ('finger printing', however, does take regional features into account). Seasonal forecasting may involve bias corrections referred to as 'calibration' – fixing the statistical distribution of the prognostic variables so that they are comparable with the observations - and they still struggle for places like northern Europe.

Despite the fact that the theme of the conference was on adaptation, there were also discussions about mitigation – which was seen as part of any real solution to the climate change problem. Woerkom talked about climate change communication and argued that people don't act on their beliefs. Energy consumption associated with life styles is difficult to change, and social pressures and expectations are some of the obstacles. He suggested that people have to be supported in the implementation.

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Guest commentary from Mauri Pelto

Changes occurring in marine terminating outlet glaciers of the Greenland Ice Sheet and ice shelves fringing the Antarctic Peninsula have altered our sense of the possible rate of response of large ice sheet-ice shelf systems. There is a shared mechanism at work that has emerged from the detailed observations of a number of researchers, that is the key to the onset and progression of the ice retreat. This mechanism is shared despite the vastly different nature of the environments of Jakobshavns Isbrae, Wilkins Ice Shelf and the Petermann Glacier.

We reviewed in a previous post the first mechanism for explaining the change in velocity of Greenland’s large outlet glacier - the Zwally effect - and why it is not the key. This mechanism relies on meltwater reaching the glacier base via moulins and reducing the friction at the base of the glacier. This idea was observed to be the cause of a brief seasonal acceleration of 10- 20 % on the Jakobshavns Glacier in 1998 and 1999 at Swiss Camp 35 km inland from the calving front (Zwally et al., 2002). Examination of recent rapid supraglacial (i.e. on the surface) lake drainage documented short term velocity changes due to such events around 10%, but little significance to the annual flow of the large glaciers outlet glaciers (Das et.al, 2008).

The second mechanism is a dynamic thinning of the terminus zone of the marine terminating outlet glacier reducing the effective bed pressure, allowing acceleration - the Jakobshavn effect. The reduced resistive force at the calving front due to the thinner ice, now experiencing greater flotation, is then propagated "up glacier" (Hughes, 1986; Thomas, 2003 and 2004). If the Jakobshavn effect is the key the velocity increase will propagate up-glacier, there will be no seasonal cycle, and thinning and acceleration would be greatest near the terminus.

That the thinning and acceleration is greatest for marine terminating outlet glaciers has indeed been demonstrated by Sole et. al. (2008). That acceleration began at the calving front and spread upglacier 20 km in 1997 and up to 55 km inland by 2003 (Joughin et al., 2004). On Helheim the thinning and velocity propagated up-glacier from the calving front. Each of the glaciers fronts did respond to tidal variations indicating they had started floating, detached from their bed (Hamilton et al, 2006). This summer, Jason Box and others at Ohio State University observed that Jakobhavns Isbrae retreated again, losing 15 km², and maintaining an accelerated pace from the northern branch of the ice stream as opposed to the greater retreat and acceleration of the southern branch 2001-2005 (Box, 2008). This was accompanied by the second consecutive year of substantial retreat of the glacier just north of Jakobshavn, Sermeq Avannarleq which had been quite stable for much of the last century (Box , 2008b). Sole et. al. (2008) also noted that the recent thinning and acceleration was not limited to just the now more famous Helheim, Jakobshavn and Kangderlugssuaq Glaciers, but included Rinks Isbrae, Equaluit, Cristian IV and all others they observed. Note the greater flow of the southern ice stream in 2000, compare to the northern ice stream in this image from Ian Joughin:

Petermann Glacier is a much different glacier than the others mentioned above. Its velocity of 2-3 m/day (Higgins, 1990) is much lower than 10-30 m/day observed on the other marine terminating outlet glaciers. It is located on the northwest corner of Greenland and certainly experiences less melting and less snowfall. The lower 80 km (in length) and 1300 km² (in area) of the glacier is afloat. This makes it (by area) the largest floating glacier in the Northern Hemisphere. The ice front is not impressive,unlike the faster outlet glaciers. The calving front protrudes a mere 5-10 m above sea level, reflecting the fact that the ice at the front is only 60-70 m thick. Further up-glacier, the ice at the grounding line is 600-700 m thick. The combination of velocity and thickness yield the volume of material calved each year. Petermann Glacier calves 0.6 km³ (Higgins, 1990), whereas Jakobshavns yields close to 40 km³. The thinning between the grounding line and the calving front is mainly via melting as the snowline is at 900 m. The low slope leads to very low velocities, giving the low-lying floating section plenty of time to melt, and surface melt ponds are common.

The Petermann Glacier lost a substantial area, 29 km² due to calving this summer (Box 2008c), and a crack well back of the calving front indicates another 150 km² is in danger. The volume of the ice lost is much less than that from the loss of a comparable area by Jakobshavn because the ice is an order of magnitude thinner. Once again the key to this glacier’s second major ice loss this decade after limited retreat in the last century, is thinning of the floating tongue, which weakens the glacier. The loss of this ice should then lead to acceleration, developing more crevassing and glacier retreat. The crack seen in the image of Petermann Glacier (ASTER image provided by Ian Howat of Ohio State) is more of a rift, like those on Larsen Ice Shelf, than a crevasse. This transverse rift is further connected to longitudinal-marginal rifts. Illustrating the poor connection of the Petermann Glacier to its margin and lack of a stabilizing force this margin has, even 15 km behind the calving front. This is not the only rift of its kind on the glacier. Also note that like on Larsen Ice Shelf the rift crosscuts surface streams.

A series of Landsat images from 2002, 2006 and 2007 illustrate the shift in the terminus and in the position of key rifts A, B and C. The distance back from the terminus has diminished for A and B from 2002 to 2007. In 2006 to 2007 the shift in the position of C is also evident.

As in the case on Jakobshavns, Helheim and others the key is the pre-conditioning phase of thinning, that leads to more calving, that leads to more acceleration, and that generates retreat. In a recent paper in press in the Journal of Glaciology Ian Howat and others examined changes in terminus position, surface elevation and flow on 32 glaciers along the southeast coast of Greenland from 200-2006. Their key conclusion was that the

… ratio of retreat to the along-flow stress-coupling length is proportional to the relative increase in speed, consistent with typical ice flow and sliding laws. This affirms that speedup results from loss of resistive stress at the front during retreat, which leads to along-flow stress transfer. Many retreats began with an increase in thinning rates near the front in the summer of 2003, a year of record high coastal-air and sea-surface temperatures.

This indicates again the importance of pre-conditioned thinning via melting.

Wilkins Ice Shelf (WIS) refused to hibernate this winter. A previous post noted that the recent collapse of Wordie Ice Shelf, Mueller Ice Shelf, Jones Ice Shelf, Larsen-A and Larsen-B Ice Shelf on the Antarctic Peninsula has made us aware of how dynamic ice shelf systems are.

The reasons for Ice Shelf collapse continue to be identified, but one key thread emerges. The decade prior to collapse the Larsen-B Ice Shelf had thinned primarily by melting of the ice shelf bottom (by the ocean) by 18 m (Shepard and others, 2003). Thinning preconditions the ice shelf for failure by weakening its connection to pinning points at the grounding line as the shelf becomes more buoyant. Glasser and Scambos (2008) observed that prior to collapse that rifts and crevasses parallel to the ice front crosscut the meltwater channels and ponds, hence, post dated them. The number and length of the rifts increased markedly in the year before collapse. There was no evidence of relict rifts, illustrating that these rifts are a feature of the last 20 years. After ice shelf collapse the ice front receded to the pre-existing rifts, and the pre-existing rifts defined the area of collapse. In this case the thinning and resultant structural weaknesses preconditioned the ice to rapid breakup, which proceeded to lose only the preconditioned portion of the ice shelf.

The WIS is buttressed by Alexander, Latady, Charcot and Rothschild islands and by numerous small ice rises, indicating that they are touching the ocean floor. WIS was examined by Braun, Humbert and Moll (2008). They found that drainage of melt ponds into crevasses were of no relevance for the break-up at WIS. On WIS the evolution of failure zones is associated with ice rises. In 1993/94, rift formation started to expand at the northern ice front. Today, the central part of WIS is intersected by long rifts formed in and around ice rises. The rifts up to tens of kilometers long evolve and coalesce prior to break-up events. The conclusion for WIS is that preconditioning of the ice shelf by connection of the rifts in the failure zones near ice rises trigger break-up events. The thinning and rifting lead to a cascade of failure.

The Feb.-April break-up left a narrow 6 km wide fractured connection to Charcot Island. Existing rifts formed between already existing fractures, crossed almost the entire northern shelf. This fragile and vulnerable area was expected to collapse further the next austral summer. However, it instead has happened this austral winter with loss of an additional 160 km² of ice. It is the first winter ice loss of an ice shelf ever observed, and so was surprising. However, looking at the image below, from the European Space Agency showing the extent of the rifts as winter began, makes this less surprising. The question is more what can possibly hold this together? The area of interconnected rifts seen is 2000 km². If this is lost an additional 3000 km² of the 13 000km² of WIS, is at risk when this connection to Charcot Island is lost (Braun, Humbert and Moll, 2008).

It appears then that glacier or ice shelf thinning is the key preconditioning factor for collapse, retreat and acceleration, whether you are in Antarctica of Greenland. The mechanisms for ice shelf thinning include basal melting (from warming ocean waters), surface melting, reduction in glacier inflow and rift development. These are interrelated mechanisms that precondition the ice shelves to collapse. On marine terminating outlet glaciers the mechanisms to trigger thinning is surface ablation causing thinning, and potentially basal melting, though not yet observed (though see this recent paper by Holland et al, 2008). Once the process begins thinner less buttressed ice enables acceleration and more calving and more retreat. There is a potential difference between the two, in glacier such as most marine terminating outlet glaciers, where the glacier flow is rapid, acceleration results from retreat and thinning. In the case of ice shelves a glacier buttressed by them will accelerate after the loss, but the slow moving ice shelf may suffer from reduced inflow. Attention will continue to be focused on these rapid responders to climate change;marine terminating glaciers in Greenland and ice shelves in Antarctica. We can look forward to more details from the extensive 2008 summer field season in Greenland and the upcoming view of the Wilkins this fall.

Unlinked References:

Higgins, A. 1990. Northern Greenland glacier velocities and calf ice production. Polar Forschung, 60, 1-23.
Howat, I., I. Joughin, M. Fahnestock, B. Smith,T. Scambos 2008. Synchronous retreat and acceleration of southeast Greenland outlet glaciers 2000–06: ice dynamics and coupling to climate.Journal of Glaciology, 54(187).
Hughes, T. (1986), The Jakobshavn effect. Geophysical Research Letters, 13, 46-48.
Thomas, R. H. Abdalati W, Frederick E, Krabill WB, Manizade S, Steffen K, (2003) Investigation of surface melting and dynamic thinning on Jakobshavn Isbrae, Greenland. Journal of Glaciology 49, 231-239.
Thomas RH (2004), Force-perturbation analysis of recent thinning and acceleration of Jakobshavn Isbrae, Greenland, Journal of Glaciology 50 (168): 57-66.

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Here at RealClimate we understandably have an intense interest in the positions of the Presidential and Vice-Presidential candidates regarding global warming and carbon emissions. What the stance bodes for future action on climate change is consequential in itself, but beyond that the ability to use sound science in this case serves as a bellweather for the candidates' whole approach to science. Whatever else you can say about the candidates, it has been encouraging that both John McCain and Barack Obama favor mandatory action to reduce US carbon emissions.

But, enter Gov. Sarah Palin, McCain's pick for VP. Palin's position on global warming has been stated quite clearly in this recent interview with the publication Newsmax , where she says "A changing environment will affect Alaska more than any other state, because of our location. I'm not one though who would attribute it to being man-made." How is this to be reconciled with McCain's position? Do they just agree to differ? What does this bode for future actions if McCain were to win the election, especially in view of the fact that, in a Cheney-esque way, Palin is likely to be put in charge of energy policy? The recent vice-presidential debate sheds some light on the issue. A full transcript of the debate is here.

Palin seems to be attempting to defuse the whole issue by claiming the cause doesn't matter. When the moderator asked her " What is true and what is false about what we have heard, read, discussed, debated about the causes of climate change," Palin responded as follows:

"PALIN: Yes. Well, as the nation's only Arctic state and being the governor of that state, Alaska feels and sees impacts of climate change more so than any other state. And we know that it's real.

I'm not one to attribute every man — activity of man to the changes in the climate. There is something to be said also for man's activities, but also for the cyclical temperature changes on our planet."

I'm pretty sure that that last statement is a garbled attempt to reiterate what she said in the Newsmax interview, but you be the judge. Unlike the previous quote, this one at least has a nod in the direction of acknowledging (tentatively) the possibility of a human influence. What's important is what comes next:

"But there are real changes going on in our climate. And I don't want to argue about the causes. What I want to argue about is, how are we going to get there to positively affect the impacts?"

Dare we say that it, in fact, very much makes a difference what is causing global warming? If CO2 really weren't a major part of the cause, what in the world would be the point of John McCain's (or anybody's) stated policy of acting to reduce emissions? And even if you were of the school that says adaptation is better than mitigation, knowing the cause is an important part of knowing what kind of climate change you have to adapt to, how long it is likely to last, and how much worse it is likely to get in the future.

Biden's answer, by comparison, was direct, straightforward, and simple:

"BIDEN: Well, I think it is manmade. I think it's clearly manmade. And, look, this probably explains the biggest fundamental difference between John McCain and Barack Obama and Sarah Palin and Joe Biden — Governor Palin and Joe Biden.

If you don't understand what the cause is, it's virtually impossible to come up with a solution. We know what the cause is. The cause is manmade. That's the cause. That's why the polar icecap is melting."

Well, maybe he left out the kind of caveats and qualifications you'd attach to the attribution of the recent loss of (North) polar sea ice if this were an AGU talk instead of a vice-presidential debate. Overall,though, the statement gets to the heart of the matter.

One can moreover doubt even Palin's commitment to dealing with the consequences of climate change. Surely, that would include doing something to save the polar bears,yet the State of Alaska (against the advice of its own wildlife biologists) is suing the Interior department over its decision to list the polar bear as "threatened" — and this despite the fact that the Bush administration put so many qualifications on the listing as to make it essentially toothless. What's even more telling is that the brief submitted to Interior drew heavily on a list of climate skeptics (including the Marshall Institute's Willie Soon) that could easily have been culled from the infamous Inhofe 400. (see this article). Palin's role in bringing this case has not been peripheral; she has been very much at the center of the effort, and has consistently questioned the causal link between CO2 and global warming in making the case. As early as Dec. 2006, she wrote to Secretary Kempthorne: ""When a species' habitat (in this case, sea ice) is declining due to climate change, but there are no discrete human activities that can be regulated or modified to effect change, what do you do?" Further information about Palin's long fight against the listing, and her view of the scientific issues involved, can be found here.

We will take this occasion to note also that Biden used the debate to reaffirm Obama's long standing position in favor of "clean coal." Whether this is a good or bad thing depends on the extent to which the candidates understand what should really be meant by this term. From the point of view of global warming, the only "clean" coal would be coal burned with 100% carbon capture and sequestration — certainly worthy of research and pilot implementation, but not by any means a technology that can be counted on at present to solve the problem. (And of course, the term "clean" is even then relative, since what mountain top removal mining does to the West Virginia hills and rivers is anything but "clean").

So there you are. We report, you decide.

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Here is a personal writeup of the Entrepreneurship for a Zero Carbon Society event by Justin Hayward of Cambridge Investment Research:
http://www.cambridgeinvestmentresearch.com/events/CIRonEZCS08.pdf

This is also to let you know of the following event:
Title: Solar Smart Heat Conference Expo 08 - 28 November New Hall Cambridge University

They say all publicity is good publicity. Well, maybe. We haven’t really sought too much publicity for Project Dirt so far, but today we are glad to report we had our first ‘interview’! Well, I guess that’s what it was, because it involved a rather large microphone and plenty of nervous laughter from Mark. But it also involved a jovial BBC sound technician from Tooting, bacon sarnies and three cups of tea. This was all in aid of a podcast, which will go out on the ‘City Bumpkin’ blog: details of which we’ll upload when it’s published.

We were also thrilled (but somewhat surprised) to find we’d had our first mention in the national press… the Guardian no less. I’m trying to keep Mark’s head from exploding though; we’ll be needing that in the next few weeks, as we gear up to raise funds to take the site further and wider!

But it’s not just us hitting the headlines; our groups are too! Food Up Front has had regular media appearances, with Kate and Seb virtually household names across most of the UK. And it seems like we’re all moving in increasingly high circles… Sue from Hyde Farm CAN in Balham played host to the Prime Minister just the other week to show him some really simple home energy solutions; you can see that film clip here.