The recent apparent abatement in the warming trend seen in some datasets (i.e. HAD/CRU & GHCN) though not in all (i.e. GISS) has been used to claim that global warming has ended. This misuse of the issue is a shame because there is actually an interesting question here, aside from the agenda-driven obfuscation. However as someone who often has to use Google to find sources on climate change, sorting the wheat from the chaff is an everyday activity.
So what has been going on? Two papers published in 2011 provide a broadly coherent picture. Kaufman et al examined the issue of temperature changes from 1998 to 2008. They found that emissions of sulphates aerosols (China's coal consumption playing a dominant role) offset most of the forcing from rising greenhouse gas emissions with dominance of La Nina ENSO phase and reduced insolation due to the solar cycle explain the lack of warming over that period. In contrast Foster and Rahmstorf consider the longer period 1979 to 2010 and find that over that whole period ENSO and volcanic forcing (stratospheric aerosols from Plinean eruptions) contribute the most with a lesser contribution from reduced solar insolation. Once these factors are allowed for Foster & Rahmstorf find that the signature of global warming is clear and unabated over that period. However both Kaufman et al and Foster & Rahmstorf consider the annual average temperature, there is new research that shows and explains a regional seasonal signal of devatiation from the pattern of global warming.
Saturday 31 December 2011
Sunday 18 December 2011
Recently (well, back in November) Dr Judah Cohen published a new paper on the linkage between Siberian snow cover and Northern Hemisphere winters. The paper By Judah Cohen and Justin Jones is "A new index for more accurate winter predictions." There's a link to it at the end of this post. I've previously commented on the possibility of increased incidence of cold winters due to low solar activity and Arctic sea-ice. I've seen those as biassing for colder winters, with Cohen's previous work on Siberian Snowfall showing a trigger for specific cold winter events. However Cohen and Jones' new index makes me wonder what room there is for the other factors.
Monday 12 December 2011
Last week there was a press conference with Jim Hansen, Eelco Rohling, & Ken Caldeira at the AGU. I'm a bit late on it, just got round to catching up on RC's coverage of it. But this is well worth watching, including the press questions at the end. Rather than use the Blogger video window - which is too small for this - here's a link to the Youtube page. The accompanying powerpoint presentation is available here.
Tuesday 6 December 2011
In my previous post I fact-checked a response to David Attenborough by Nigel Lawson. This is based upon an extensive piece in the 3 - 9 December issue of the Radio Times (RT). Now as promised I'll look at David Attenborough's claims, which are quoted below as blockquotes.
Sunday 4 December 2011
In the 3 - 9 December issue of the Radio Times (RT) there is a substantial piece by Sir David Attenborough about the final episode of Frozen Planet - On Thin Ice. I've fact checked that too, but here I'll fact check Lord Nigel Lawson's response, printed on page 15 of that issue of RT. The blockquotes below are Lawson's factual statements from the RT article.
Saturday 3 December 2011
A recent paper by Kinnard et al examines the history of sea-ice using proxy data and recent observations. It really puts what's been going on recently in context and is another brick in the wall of evidence showing that current events in the Arctic are so unusual that they demand explanation and cannot simply be dismissed as being down to natural factors when anthropogenic warming is an ongoing process. Skeptical Science have covered Kinnard et al, now Tamino has a good post with an observation I was going to comment on over there, but it could do with some expanding. And as I have a blog...