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Josh May 26, 2013 Climate: MetOffice Climate: Models Josh
;)
Following Doug's extraordinary post this morning we imagine Julia Slingo, Met Office, offering an apology.
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Updated text H/t Doug
Bishop Hill Apr 17, 2013 Climate: Models Climate: Surface Roy Spencer has posted up a very useful comparison of lower tropospheric temperatures against model predictions so that we can assess if the models are doing any better in the upper atmosphere.
They aren't.
Bishop Hill Apr 13, 2013 Climate: Models Climate: sensitivity The Potsdam Institute has something of a reputation for being a research unit of loose morals. The letter written by one of their star scientists in the Economist suggests that their grasp of the scientific method is even looser.
Prof Anders Levermann's missive responds to the Economist's article on climate sensitivity and is pretty jaw-dropping:
SIR – The reduced warming of the past decade is brief and can be understood in terms of natural fluctuations from the El Niño phenomenon, the effects of volcanoes, the solar cycle and the uptake of heat from the oceans, which continues, in contrast to your statement. There are and will always be fluctuations in global temperature, but the underlying trend is robust, man-made and consistent with a climate sensitivity of around 3°C.
Bishop Hill Apr 13, 2013 Climate: Models Warren Pearce has written an interesting layman's guide to sceptical arguments on climate change at the Making Science Public blog. He covers issues such as Climategate and science by press release in what I think is a reasonable summary.
The section on computer models was also quite good:
Computer models are critical to climate science and the projected effects of carbon dioxide emissions on global temperatures. Criticisms are levelled at these models sometimes focus on the assumptions upon which they are based. More broadly, there are worries about the weight afforded to these models over empirical observation. In other words, can we not learn more from existing temperature data than projections?
However, this elicited a comment from Gavin Schmidt that misrepresents things completely:
...the a priori demonisation of ‘models’ as a tool for making forecasts makes no logical sense – since of course we don’t have ‘empirical data’ from the future. Instead, results from coherent and physics-based models are dismissed in favor of untested and unevaluated heuristics – ‘no change!’, ‘new ice age!’, etc.
Who said anything about a priori demonisation of models? Sceptics dismiss the output of climate models as tools for policymaking because GCMs have no proven ability to make valid forecasts - to the extent that their predictions have been tested, they are running much too hot. If climate scientists want to play with GCMs, they are welcome to try. They will learn much along the way. Just don't expect us to believe the output is a valid forecast (in Gavin's words) without some evidence.
Bishop Hill Apr 8, 2013 Climate: Models Climate: Sceptics BH regulars Tamsin Edwards and Jonathan Jones are facing off in a debate about the usefulness of climate models at the Cheltenham Science Festival on 7 June.
Computer-generated models are used to predict future climates, but how much faith should we put in them to guide future actions? Should we treat their predictions as fact or fiction? With the hot topic of climate change ever current, can we wait to find out? Join climate scientist Tamsin Edwards, sceptic Jonathan Jones and policy adviser Claire Craig. Temperatures could rise in this session…
Details here, although tickets don't go on sale for a couple of weeks.
Bishop Hill Mar 27, 2013 Climate: Models GWPF David Whitehouse's response to the CCC blog post is pretty devastating:
If this kind of data were from a drugs trial it would have been stopped long ago, even allowing for the little understood stopping bias effect which occurs when looking for the first signs of effectiveness or harm in such trials.
Bishop Hill Mar 26, 2013 Climate: Models Climate: Surface Climate: sensitivity Brian Hoskins and Steve Smith, advisers to the Committee on Climate Change, have written (yet another) riposte to David Rose's article in the Mail on Sunday. This is crazy, crazy stuff:
A chart of observed global temperatures against climate model outputs is the main evidence provided in the article. It claims that the chart “blows apart the scientific basis” for reducing emissions. This is simply incorrect, and reveals a misunderstanding of what the chart shows – a pattern of observed temperature over the last sixty years within the range of model outputs (see detailed notes below).
Bishop Hill Mar 19, 2013 Climate: Models Climate: Surface A couple more reactions to David Rose's article have appeared.
First up is James Annan, who feels that his views have been misrepresented. Rose quoted Annan as saying this:
James Annan, of Frontier Research For Global Change, a prominent ‘warmist’, recently said high estimates for climate sensitivity now look ‘increasingly untenable’, with the true figure likely to be about half of the IPCC prediction in its last report in 2007.
Bishop Hill Mar 18, 2013 Climate: Models Climate: Surface Climate: sensitivity In the wake of David Rose's Mail on Sunday article yesterday, Piers Forster tweeted that he was unimpressed with the article. I asked him if he would be willing to set out why in a bit more detail and this is his response:
It's fine to say that current models overestimate the last decade of warming. They clearly do, and as I say in my quote I think we can rule out some high sensitivity values because of this. But to do a far comparison you need to remove the effects of variability. Note also that some model runs also get the temperature evolution pretty right - although the majority don't. Even with a suggested ECS of around 2.5 C or so we can end up with a very significant climate change by 2100 if we don't do something - therefore I think the tone of the article in terms of its implications for the IPCC, climate science and the climate itself are all wrong.
He also sent the full quote that he gave Rose for his article, which gives some context.
Basically, the climate sensitivity has always been very uncertain. > estimates have put it somewhere between 1 to 5 C for a doubling of CO2. The IPCC best estimate has been around 3C. The fact that global surface temps haven't risen in the last 15 years, combined with good knowledge of the forcing terms changing climate over the satellite era: greenhouse gases, volcanoes, solar changes and aerosol is beginning to make the high estimates unlikely. Given this, i would put the best estimate using this evidence around 2.5 C. There are still uncertainties though particularly in heat going into the ocean, but climate sensitivities above 3.5C or so don't seem to fit. Keep in mind that this is only one line of evidence for quantifying climate sensitivity. Other lines of evidence have been able to firm up the bottom end. We now have good observational evidence for a positive water vapour feedback and even clouds, which have always been the largest headache in climate change, are beginning to be understood and a positive cloud feedback is looking more likely. This line of evidence helps rule out climate sensitivities below 2C. So I see it very much as a positive story that careful science ( and time) is helping to reduce the most significant uncertainty in climate science.
This thread will be tightly moderated for tone and relevance.
Bishop Hill Mar 17, 2013 Climate: Models Climate: Surface Climate: sensitivity David Rose, writing in the Mail on Sunday, has penned a long feature on the temperature slowdown and what this implies about UK energy policy. I don't know about you, but the Mail on Sunday's willingness to publish science-heavy articles of this kind really should be celebrated.
There are plenty of scientific big-hitters in there too: the article features quotes by Judy Curry, Myles Allen, James Annan and Piers Forster, so one would think that it would be hard for anyone to dispute that Rose is presenting a legitimate view of the science. However, the reaction from sci-blogger (and occasional Guardian writer) Martin Robbins seems to suggest not:
Wow - the Mail on Sunday have gone into full on bat-shit-crazy conspiracy theory mode… pic.twitter.com/YW2dPyNpTK
Whoever David Rose is, his interpretation of that graph is illiterate. Either it's a deliberate lie, or he's barely capable of functioning.
I've asked Robbins to expand on why he thinks the interpretation is illiterate and what conspiracy theory Rose is putting forward.
No reply as yet. Hmm.
Bishop Hill Mar 5, 2013 Climate: Models Education American schoolchildren are to have what looks like a monolithic view of global warming imposed upon them:
New national science standards that make the teaching of global warming part of the public school curriculum are slated to be released this month, potentially ending an era in which climate skepticism has been allowed to seep into the nation's classrooms.
They recommend that educators teach the evidence for man-made climate change starting as early as elementary school and incorporate it into all science classes, ranging from earth science to chemistry. By eighth grade, students should understand that "human activities, such as the release of greenhouse gases from burning fossil fuels, are major factors in the current rise in Earth’s mean surface temperature (global warming)," the standards say.
Bishop Hill Jan 10, 2013 Climate: MetOffice Climate: Models I'm still suffering. Even whisky isn't working. It must be serious.
In the meantime, Paul Homewood has found something interesting about the Met Office's forecasts.
Bishop Hill Jan 9, 2013 Climate: MetOffice Climate: Models The rumpus over the Met Office's downgrading of its climate predictions rumbles on (much like my lurgy!). The Mail covered the story yesterday evening (H/T Jonathan Jones), and included a couple of interesting quotes.
Graham Stringer:
Labour MP Graham Stringer said the Met Office’s short-term forecasts had improved, but their climate change analysis was ‘poor’.
He said: ‘By putting out the information on Christmas Eve they were just burying bad news – that they have got their climate change forecast wrong.
‘For a science-based organisation, they should be more up front, both about their successes and failures.’
Bishop Hill A couple of posts that I simply must point out to readers. Firstly, Steve M is back in the saddle at Climate Audit, reviewing his recent visit to the AGU and making some disturbing revelations about the AGU's welcoming back of Peter Gleick into the fold.
Gleick’s welcome back to AGU prominence – without serving even the equivalent of a game’s suspension – was pretty startling, given his admitted identity fraud and distribution (and probable fabrication) of a forged document. Last year, then AGU President Mike McPhadren, a colleague of Eric Steig’s at the University of Washington, had stated on behalf of AGU that Gleick had “compromised AGU’s credibility as a scientific society” and that his “transgression cannot be condoned”. McPhadren stated that AGU‘s “guiding core value” was “excellence and integrity in everything we do” – values that would seem to be inconsistent with identity fraud and distribution and/or fabrication of forged documents, even by the relaxed standards of academic institutions.
Meanwhile, Tallbloke and his readers have uncovered a downwards revision in the Met Office's temperature projections. It's interesting to wonder why a statistically insignificant rainfall trend was worthy of a Met Office press release while a major reining back on the projections wasn't.
Bishop Hill Dec 18, 2012 Climate: Models Anthony posted this startling image from the IPCC's draft report. It shows the forecasts of atmospheric methane concentrations from the earlier assessment reports and how they have turned out against reality.
;)
Forecasting is difficult. Especially of the future.
