
[Read more…] about Butterflies, tornadoes and climate modelling
Climate science from climate scientists...
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[Read more…] about Butterflies, tornadoes and climate modelling
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Guest Commentary by Mauri Pelto
The net loss in volume and hence sea level contribution of the Greenland Ice Sheet (GIS) has doubled in recent years from 90 to 220 cubic kilometers/year has been noted recently (Rignot and Kanagaratnam, 2007). The main cause of this increase is the acceleration of several large outlet glaciers. There has also been an alarming increase in the number of photographs of meltwater draining into a moulin somewhere on the GIS, often near Swiss Camp (35 km inland from the calving front). The story goes—warmer temperatures, more surface melting, more meltwater draining through moulins to glacier base, lubricating glacier bed, reducing friction, increasing velocity, and finally raising sea level. Examining this issue two years RealClimate suggested this was likely the correct story. A number of recent results suggest that we need to take another look at this story.
[Read more…] about Moulins, Calving Fronts and Greenland Outlet Glacier Acceleration
by Stefan
In January, we presented Lesson 1 in model-data comparison: if you are comparing noisy data to a model trend, make sure you have enough data for them to show a statistically significant trend. This was in response to a graph by Roger Pielke Jr. presented in the New York Times Tierney Lab Blog that compared observations to IPCC projections over an 8-year period. We showed that this period is too short for a meaningful trend comparison.
This week, the story has taken a curious new twist. In a letter published in Nature Geoscience, Pielke presents such a comparison for a longer period, 1990-2007 (see Figure). Lesson 1 learned – 17 years is sufficient. In fact, the very first figure of last year’s IPCC report presents almost the same comparison (see second Figure).
[Read more…] about Model-data-comparison, Lesson 2
by Gavin
What is the long term sensitivity to increasing CO2? What, indeed, does long term sensitivity even mean? Jim Hansen and some colleagues (not including me) have a preprint available that claims that it is around 6ºC based on paleo-climate evidence. Since that is significantly larger than the ‘standard’ climate sensitivity we’ve often talked about, it’s worth looking at in more detail.
by Gavin
Nature Geoscience has two commentaries this month on science blogging – one from me and another from Myles Allen (see also these blog posts on the subject). My piece tries to make the point that most of what scientists know is “tacit” (i.e. not explicitly or often written down in the technical literature) and it is that knowledge that allows them to quickly distinguish (with reasonable accuracy) what new papers are worth looking at in detail and which are not. This context is what provides RC (and other science sites) with the confidence to comment both on new scientific papers and on the media coverage they receive.
Myles’ piece stresses that criticism of papers in the peer-reviewed literature needs to be in the peer-reviewed literature and suggests that informal criticism (such as on a blog) might undermine that.
We actually agree that there is a real tension between a quick and dirty pointing out of obvious problems in a published paper (such as the Douglass et al paper last December) and doing the much more substantial work and extra analysis that would merit a peer-reviewed response. The approaches are not however necessarily opposed (for instance, our response to the Schwartz paper last year, which has also lead to a submitted comment). But given everyone’s limited time (and the journals’ limited space), there are fewer official rebuttals submitted and published than there are actual complaints. Furthermore, it is exceedingly rare to write a formal comment on an particularly exceptional paper, with the results that complaints are more common in the peer reviewed literature than applause. In fact, there is much to applaud in modern science, and we like to think that RC plays a positive role in highlighting some of the more important and exciting results that appear.
Myles’ piece, while ending up on a worthwhile point of discussion, illustrates it (in my opinion) with a rather misplaced example that involves RC – a post and follow-up on the Stainforth et al (2005) paper and the media coverage it got. The original post dealt in part with how the new climateprediction.net model runs affected our existing expectation for what climate sensitivity is and whether they justified a revision of any projections into the future. The second post came in the aftermath of a rather poor piece of journalism on BBC Radio 4 that implied (completely unjustifiably) that the CPDN team were deliberately misleading the public about the importance of their work. We discussed then (as we have in many other cases) whether some of the responsibility for overheated or inaccurate press actually belongs to the press release itself and whether we (as a community) could do better at providing more context in such cases. The reason why this isn’t really germane to Myles’ point is that we didn’t criticise the paper itself at all. We thought then (and think now) that the CPDN effort is extremely worthwhile and that lessons from it will be informing model simulations some time into the future. Our criticisms (such as they were) were mainly associated instead with the perception of the paper in parts of the media and wider community – something that is not at all appropriate for a peer-reviewed comment.
This isn’t the place to rehash the climate sensitivity issue (I promise a new post on that shortly), so that will be deemed off-topic. However, we’d be very interested in any comments on the fundamental issue raised – how do (or should) science blogs and traditional peer-review intersect and whether Myles’ perception that they are in conflict is widely shared.
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Guest Commentary by Frank Zeman
One of the central challenges of controlling anthropogenic climate change is developing technologies that deal with emissions from small, dispersed sources such as automobiles and residential houses. Capturing these emissions is more difficult as they are too small to support infrastructure, such as pipelines, and may be mobile, as with cars. For these reasons, proposed solutions, such as switching to using hydrogen or electricity as a fuel, rely on the carbon-free generation of electricity or hydrogen. That implies that the fuel must be made either by renewable generation (wind, solar, geothermal etc.), nuclear or by facilities that capture the carbon dioxide and store it (CCS).
There is however an alternative that gets some occasional attention: Air Capture (for instance, here or here). The idea would be to let people emit the carbon dioxide at the source but then capture it directly from the atmosphere at a separate facility.
by raypierre


[Read more…] about Venus Unveiled
by rasmus
Knud Jahnke and Rasmus Benestad
After having watched a new documentary called the ‘Cloud Mystery’ – and especially the bit about the galaxy (approximately 2 – 4 minutes into the linked video clip) – we realised that a very interesting point has been missed in earlier discussions about ‘climate, galactic cosmic rays and the evolution of the Milky Way galaxy.
It is claimed in ‘The Cloud Mystery’, the book ‘The Chilling Stars’, and related articles that our solar system takes about 250 million years to circle the Milky Way galaxy and that our solar system crosses one of the spiral arms about every ~150 million years (Shaviv 2003).
But is this true? Most likely not. As we will discuss below, this claim is seriously at odds with astrophysical data.
[Read more…] about A Galactic glitch
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By John Fleck and William Connolley
To veterans of the Climate Wars, the old 1970s global cooling canard – “How can we believe climate scientists about global warming today when back in the 1970s they told us an ice age was imminent?” – must seem like a never-ending game of Whack-a-mole. One of us (WMC) has devoted years to whacking down the mole (see here, here and here, for example), while the other of us (JF) sees the mole pop up anew in his in box every time he quotes contemporary scientific views regarding climate change in his newspaper stories.
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by Gavin
“during this year a most dread portent took place. For the sun gave forth its light without brightness… and it seemed exceedingly like the sun in eclipse, for the beams it shed were not clear.”
This quote from Procopius of Caesarea is matched by other sources from around the world pointing to something – often described as a ‘dry fog’ – and accompanied by a cold summer, crop failures and a host of other problems. There’s been a TV special, books and much newsprint speculating on its cause – volcanoes, comets and other catastrophes have been suggested. But this week there comes a new paper in GRL (Larsen et al, 2008) which may provide a definitive answer….
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