Eduardo Zorita has an interesting review of McShane & Wyner's paper on the statistics of paleoclimate reconstructions. He takes them to task for not understanding the actual methods used by paleo people and in particular those used by Mann et al in the Hockey Stick papers. Although one can point to the foggy writing in MBH98 in defence of M and W, Eduardo's point that they should have worked more closely with paleo people is fair enough. That said, Eduardo does spend quite a lot of his review criticising the preamble to the paper rather than the guts of the thing.
When he does get onto the paper, he is less critical, but not convinced. He describes M&W's comparison of reconstructions based on proxies to those from various forms of noise as "interesting and probably correct" but doubts its usefulness because they have used a method that is not used by paleo people. I'm not sure about this - surely if there is a real temperature signal in the proxies, they should outperform noise regardless of the method?
There is a modicum of agreement on the last part of the paper though, with Zorita agreeing with M&W's conclusion that the uncertainties in paleo reconstructions have been underestimated. However, he says that this observation is...
...hardly revolutionary. Already the NRC assessment on millennial reconstructions and other later papers indicate that the uncertainties are much larger than those included in the hockey stick and that the underestimation of past variability is ubiquitous.
I guess the IPCC missed that memo.
...but not mine.
Firstly, one should always accentuate the positive first, so I am going to praise Bob Ward for eschewing the words "denier" and "denialist". This is a good thing and will help elevate the tone of the debate. I assume this was his idea rather than something that was forced upon him by the Guardian.
Human hunters off the hook? Climate change caused wooly mammoths' extinction, say scientists.
Uh huh. So how do they know this?
Climate change, rather than human hunters, drove the wooly mammoth to extinction. That’s the claim from scientists who say that the hairy beasts lost their grazing grounds as forests rapidly replaced grasslands after the last ice age, roughly 20,000 years ago. The researchers used palaeoclimate and vegetation models to simulate the plant cover across the mammoths’ habitat around that time.
Yes folks, it's a modelling study. Another one. From the paper's abstract, the researchers took output from the Hadley Centre's Unified Climate Model and pumped it into another model which purports to simulate how a variety of plants react to temperature changes. So even if the vegetation model works it still relies on the Hadley Centre model being something one can rely on. Is it just me that finds this all rather unconvincing. I mean is the Hadley Centre Unified Model something you'd want to bet the house on?
Well, according to this article, the Unified Model is:
"the same model that is used to produce every weather forecast you see on British terrestrial television."
Climatologist Hans Joachim Schellnhuber of the Potsdam Institute is interviewed in Spiegel. The interviewer even tries a few challenging questions:
SPIEGEL: As climate adviser to the chancellor, you have a particularly high profile. Because of your frequently ominous predictions, critics have dubbed you the "Cassandra of Potsdam," after the figure in Greek mythology whose predictions always went unheard. Why do you always have to scare people?
Schellnhuber: Let me answer your provocative question in an objective way. As an expert, it's possible that I tend to point to dangers and risks more than to opportunities and possibilities -- similarly to an engineer who builds a bridge and has to make people aware of everything that could cause it to collapse. Warning against a possible accident is in fact intended to reduce the likelihood of an accident. And a sudden shift in the climate could have truly catastrophic consequences. Besides, in Greek mythology Cassandra was always right -- unfortunately.
SPIEGEL: Does that justify constantly predicting the end of the world?
Schellnhuber: Naturally, we have to be careful not to dramatize things. After all, scientific credibility is our unique selling point. But I do confess that when you have the feeling that people just aren't listening, it becomes very tempting to turn up the volume. Naturally, we have to resist this temptation.
My publisher wonders if I am going to write to the Scottish Review of Books and ask to respond to Alastair McIntosh's review. School is back tomorrow and there is something of a backlog of real work to complete. But I thought I would set down a few thoughts and see if I can bring myself to write anything.
The Met Office's Peter Thorne is running a blog to go alongside the surfacetemperatures.org initiative. This project intends to design a new surface temperature dataset. Public views are being sought on the project although time is somewhat short now so if you are interested you need to be quick.
(H/T Oliver Morton)
The argument that carbon dioxide is plant food and that we should welcome increased concentrations of the stuff as leading to bumper crop yields is one that is not given much credence by the other side of the global warming debate. Perhaps they should think again, as this article, recently published in the Royal Society's Phil Trans B, suggests that there is much truth in it.
CO2 enrichment is likely to increase yields of most crops by approximately 13 per cent but leave yields of C4 crops unchanged. It will tend to reduce water consumption by all crops, but this effect will be approximately cancelled out by the effect of the increased temperature on evaporation rates. In many places increased temperature will provide opportunities to manipulate agronomy to improve crop performance. Ozone concentration increases will decrease yields by 5 per cent or more.
Plant breeders will probably be able to increase yields considerably in the CO2-enriched environment of the future, and most weeds and airborne pests and diseases should remain controllable, so long as policy changes do not remove too many types of crop-protection chemicals. However, soil-borne pathogens are likely to be an increasing problem when warmer weather will increase their multiplication rates; control is likely to need a transgenic approach to breeding for resistance. There is a large gap between achievable yields and those delivered by farmers, even in the most efficient agricultural systems. A gap is inevitable, but there are large differences between farmers, even between those who have used the same resources. If this gap is closed and accompanied by improvements in potential yields then there is a good prospect that crop production will increase by approximately 50 per cent or more by 2050 without extra land. However, the demands for land to produce bio-energy have not been factored into these calculations.
You could almost get the impression that the biggest threat to the food supply is coming from government.
(H/T Roddy Campbell)
This thread is for discussion of the McShane and Wyner paper, which looks as though it is going to be a pretty significant contribution to the Hockey Stick debate. Well, it has got Real Climate deleting comments again anyway...
Bob Ward has a letter in the Telegraph bemoaning (quite correctly) attempts to link the hot weather in Russia and the Pakistan floods to climate change.
SIR – The recent extreme weather in Pakistan, Russia and China is not “proof of climate change” (report, August 11).
While increases in the intensity and frequency of heatwaves, droughts and heavy rainfall in some parts of the world are consistent with the expected impacts of the rise in average temperature, it is long-term trends in extreme weather that provide evidence for a changing climate.
Researchers must be careful about presenting the evidence for global warming. Every warm or wet event cited as proof may legitimise the erroneous portrayal of outbreaks of cold weather, such as those in northern Europe and eastern North America last winter, as evidence that global warming has stopped or does not exist. Such apparent contradictions increase public confusion.
I read somewhere that we're going to have another cold winter, at least according to some forecasters. I wonder if Bob read the same article.