A recent conference presentation at AGU (reported here) while confirming that global sea level is indeed rising (in line with other estimates), showed that Arctic sea levels may actually be falling. On the face of it these preliminary results are a little puzzling (though note that this isn’t yet a properly peer reviewed paper, and so may not reflect what ends up in the journal), but it does reveal some of the complexities in analysing sea level in relatively small enclosed basins and so a brief overview of the different factors involved is probably useful. [Read more…] about Sea level in the Arctic
Current volcanic activity and climate?
There has been a lot in the news recently about current volcanic activity – Merapi in Indonesia and Bezymianny in the Kamchatka peninsula in Russia, but while most reports have focussed on the very real dangers to the local populace and air traffic, volcanoes can have important impacts on climate as well. However, there are a number of conditions that need to be fulfilled before an eruption will show up in the climate record. [Read more…] about Current volcanic activity and climate?
MY Review of Books
I’ve finally got round to reading a number of the many climate change-related books that have been published in recent months. These books seem to have caught the public imagination in ways that are different than in the past, and so it’s worth examining how they do. The three I’ve read are; Eugene Linden’s The Winds of Change, Elizabeth Kolbert’s Field Notes from a Catastrophe and Tim Flannery’s The Weather Makers. The first two writers are journalists, while the third is a scientist by background, and while there is some overlap in contents all of them, they are clearly distinct works in quite different styles. I’ll mostly stick to commenting on the science though… [Read more…] about MY Review of Books
How not to write a press release
A recent BBC radio documentary on the possible over-selling of climate change, focussed on the link between high profile papers appearing in Nature or Science, the press releases and the subsequent press coverage. One of the examples chosen was the Stainforth et al climateprediction.net paper that reported the ranges of climate sensitivity within their super-ensemble of perturbed physics runs. While there was a lot of interesting science in this paper (the new methodology, the range of results etc.) which fully justified its appearance in Nature, we were quite critical of their basic conclusion – that climate sensitivities significantly higher than the standard range (1.5 – 4.5ºC) were plausible – because there is significant other data, predominantly from paleo-climate, that pretty much rule those high numbers out (as we discussed again recently). The press coverage of the paper mostly picked up on the very high end sensitivities (up to 11ºC) and often confused the notion of an equilibirum sensitivity with an actual prediction for 2100 and this lead to some pretty way-out headlines. I think all involved would agree that this was not a big step forward in the public understanding of science.
Why did this happen? Is it because the scientists were being ‘alarmist’, or was it more related to a certain naivety in how public relations and the media work? And more importantly, what can scientists do to help ensure that media coverage is a fair reflection of their work? [Read more…] about How not to write a press release
Tropical Cyclones workshop
One of the nice things about a being a scientist is that you can sometimes go to workshops and meetings and actually hear something new now and again. At the well-timed Tropical Cyclones and Climate Workshop at Columbia a week or so ago, I got a chance to sit in and listen to Emanuel, Landsea, Knutson and Bell talking about their recent work, but I also got to hear some new voices (and issues) in the discussion. It was all pretty enlightening even if it didn’t end up in complete reconciliation of the different views. [Read more…] about Tropical Cyclones workshop
Pielke père et fils in Nature
There’s an interesting profile on Roger Pielke Jr. and Sr. in Nature this week. As readers here are probably aware, both of them have blogs (Prometheus for Jr., Climate Science for Sr.) and both have contributed to the discussions on RealClimate. Readers will also be aware that the discussions have at times been heated, though have usually remained collegial. There have been a few times when the discussion may have seemed to be at cross-purposes, but overall the exchanges have been enlightening.
[Read more…] about Pielke père et fils in Nature
Climate sensitivity: Plus ça change…
Almost 30 years ago, Jule Charney made the first modern estimate of the range of climate sensitivity to a doubling of CO2. He took the average from two climate models (2ºC from Suki Manabe at GFDL, 4ºC from Jim Hansen at GISS) to get a mean of 3ºC, added half a degree on either side for the error and produced the canonical 1.5-4.5ºC range which survived unscathed even up to the IPCC TAR (2001) report. Admittedly, this was not the most sophisticated calculation ever, but individual analyses based on various approaches have not generally been able to improve substantially on this rough estimate, and indeed, have often suggested that quite high numbers (>6ºC) were difficult to completely rule out. However, a new paper in GRL this week by Annan and Hargreaves combines a number of these independent estimates to come up with the strong statement that the most likely value is about 2.9ºC with a 95% probability that the value is less than 4.5ºC. [Read more…] about Climate sensitivity: Plus ça change…
Reactions to tighter hurricane intensity/SST link
There was another twist to the hurricanes/global warming issue in Science Express on Friday where a new paper from the Webster/Curry team just appeared. This study, lead by Carlos Hoyos, crosses a few t’s and dots a couple of i’s on the connection of increasing numbers of intense hurricanes (Cat. 4 and 5) to sea surface temperatures (SST). Basically, they looked at a number of other key variables for hurricane intensity (like wind shear and humidity) and examined whether there was any pattern to those variables across the different ocean basins that they study. Bottom line? None of the other variables have as much explanatory power for the long term trends as SST which is the only consistently trending constituent in the mix. So far, so un-surprising. However, one interesting aspect of this story is that almost all the key players in the ongoing debate were interviewed by different journalists in various media and those comments are probably more useful for gauging the state of play than the details of the new paper itself. [Read more…] about Reactions to tighter hurricane intensity/SST link
Meteors, Nuclear Tests and Global Warming
What is one to make of a recent press release and submitted preprint blaming global warming on the Tunguska meteor event in 1908? Well, although it is not unknown for impact events to affect climate (the K/T boundary event springs to mind) there are a number of hurdles for any such theory to overcome before it moves into the mainstream from the wilder shores of unsubstantiated speculation.
Firstly, one would anticipate that immediate effects of the impact on climate would be strongest near the time of the impact (allowing for some inertia in the system) and decay away subsequently. Secondly, the timescales for any mechanism associated with the impact (in this case disruption of the atmopsheric water vapour) would need to be in line with the change one hopes to explain. And thirdly, one has to show that this explanation is better than the alternatives. Unfortunately, none of of these requirements are met by this hypothesis. [Read more…] about Meteors, Nuclear Tests and Global Warming
Art and climate
As anecdotal evidence of past climate change goes, some of the most pleasant to contemplate involve paintings of supposedly typical events that involve the weather. Given the flourishing of secular themes in European art from the Renaissance on, most of this art comes from the 16th to 19th centuries. As readers here will know, this coincides (in the public mind at least) with the so-called ‘Little Ice Age’ and somewhat inevitably this canon of work has been combed over with a fine tooth comb for evidence of particularly cold conditions.
The image that brought this issue to mind was seeing ‘Washington crossing the Delaware’ at the Met the other day and seeing the iceberg-like ice it was imagined (75 years after the event) that the rebels had had to row through in 1776. The first thing I noticed was that the ice is completely wrong for a river (which is just one of the errors associated with this picture apparently). River ice is almost always of the ‘pancake’ variety (as this photo from the Hudson river shows), and doesn’t form ‘growlers’. However, the confusion of artistic license with climatology appears to be a bit of a theme in other oft-cited works as well…. [Read more…] about Art and climate