It's been a long, hard work week, and in my line of work that means all seven days - week after week, month after month, year after year. I'm tired, sore, hungry and cold. Normal in other words.

My poor old brain is tired too, so I'm going to cheese out today and just point at things that seem interesting, and that I may return to, and speak about, when less tired.

Richard Posner, from a response to responses on comments he made about climate change. You follow the thought threads if you're interested.

The global warming skeptics point out that there are natural climate fluctuations, that anticapitalists are enthusiastic beaters of the drum for action against global warming, and that global warming would have good effects on agriculture in northern climes. These points are correct, but do not support the skeptical position. The existence of natural climate fluctuations increases the risk from human-caused global warming, because increased atmospheric concentrations of carbon dioxide increase the amplitude of the fluctuations. The fact that the motives of some of the people who are worried about global warming are political is irrelevant to the scientific issues, not only because scientists use apolitical methods of testing their hypotheses, but also because there are politics on both sides of the global warming debate: if leftwingers exaggerate the danger of global warming, rightwingers belittle them excessively. . .

Some of the skeptics believe that Becker and I are part of a leftwing conspiracy to foist a false belief in global warming on the world. Anyone familiar with our work would know that we are conservatives. What is true and important is that there is considerable uncertainty about predictions of climate change. The climatologists' consensus may prove incorrect. What is striking however is the thinning of the ranks of the dissenters over time.

The emphasis is mine, and highlights a speculation stated as evidence. Consume with caution.

It's a lot to ask of folks, but it would be useful to bring political views to bear on policy responses rather than threat analyses. The risk seems real, if exaggerated. The scientists might all be deluded, but that seems to be a low probability possibility.

Each scientist might be hyper-focused on a narrow aspect of the issue - and so fail to see the large picture - and that means that there's a lot of work for synthesists: those who can meld many bits of the picture together to get a coherent image.

For all of Posner's many faults he is one of the better synthesists.

Update:

Posner asserted that The existence of natural climate fluctuations increases the risk from human-caused global warming, because increased atmospheric concentrations of carbon dioxide increase the amplitude of the fluctuations. This depends on what is fluctuating and how strongly it does so. It may be, as some claim, that the GHG contribution to change is insignificant by comparison. There are those who agree that the climate has warmed but don't subscribe to the GHG school of thought. For example, some place significant emphasis on land use changes. Another group studies solar effects, which would include not only the local star but all the stars that shine.

This was discussed a few years ago here and updated since then as new papers have come out. There have been few papers, and few are studying the issue. Why? The snark-in-chief notes that It's wrong to politicize science. But, that has certainly happened.

Twenty years ago, climate research became politicised in favour of one particular hypothesis, which redefined the subject as the study of the effect of greenhouse gases. As a result, the rebellious spirits essential for innovative and trustworthy science are greeted with impediments to their research careers. And while the media usually find mavericks at least entertaining, in this case they often imagine that anyone who doubts the hypothesis of man-made global warming must be in the pay of the oil companies. As a result, some key discoveries in climate research go almost unreported. . .

. . . one awkward question you can ask, when you’re forking out those extra taxes for climate change, is “Why is east Antarctica getting colder?” It makes no sense at all if carbon dioxide is driving global warming. While you’re at it, you might inquire whether Gordon Brown will give you a refund if it’s confirmed that global warming has stopped. The best measurements of global air temperatures come from American weather satellites, and they show wobbles but no overall change since 1999.

That levelling off is just what is expected by the chief rival hypothesis, which says that the sun drives climate changes more emphatically than greenhouse gases do. After becoming much more active during the 20th century, the sun now stands at a high but roughly level state of activity. Solar physicists warn of possible global cooling, should the sun revert to the lazier mood it was in during the Little Ice Age 300 years ago.

The author, former New Scientist editor Nigel Calder, has a book to promote, The Chilling Stars: A new theory of climate change, co-authored with Henrik Svensmark. Svensmark proposed a theory years ago to explain historical climate variations by correlating weather satellite data on cloudiness with atomic particles coming in from exploded stars. More cosmic rays, more clouds, cooler earth. And the reverse. Some of the important papers on solar influence on clouds by Nir J. Shaviv and Ján Veizer reference Svensmark's theories.

I'm not sure that they deal with magnetic field variations, but that's an issue too on earth since most cosmic rays, including those from the local star, are deflected by the earth's magnetic field. That field varies, even reverses polarity, and for extended periods can be all but gone during a reversal episode. If the magnetic shield fluctuates as well as the cosmic bombardment rate - and that does in fact affect clouds and so albedo - there might be strong effects.

Few make such arguments, and my muddled retelling may just be bloviation, but Calder has a point that the ideas are discouraged in ways that affect careers, in effect suppressing inquiry. This is related to the nasty behaviors discussed in Burning Bruno.

I'd like to see these subjects studied. Even if they don't upset the GHG school the findings will be useful since we get a wide variety of solar effects on a cyclical basis - everything from scrambled satellites to a potential for severe harm to the electric grid and network communications if a large CME with a southern polarity hits. There's still a lot of unanswered or even unasked questions. And the magnetic field has been weakening, perhaps signalling an impending reversal, though the time frame is unknown. It may be thousands of years away, but we don't know. We're due.

Update:

I noted above that "some place significant emphasis on land use changes". This is a huge subject, one that I'm keenly interested in since I work the land. Philip scratches it a little.

Soil organic matter, at roughly 1500 GtC, is the single largest compartment of carbon in the active biogeochemical cycle. At 60 GtC annual flux (in either direction), it is 10 times larger than the 5.5 GtC flux due to burning fossil fuel. Yet soil is the component of the carbon cycle that we know the least about.

Most soil scientists agree with the unvalidated concept that soil carbon levels will likely decline in step with temperature increases. Higher biological activity will result in more decomposition of organic matter. One certainly sees a similar relationship between soil carbon and temperature when comparing the effect of elevation, aspect and latitude. That we have yet to validate it is telling.

I hope to find time to dig a little deeper in a separate post. There are a lot of seemingly contradictory factors. For example, decomposition of soil organic matter in warmer scenarios is offset to some extent by increased production of new organic matter. The cycle speeds up but it isn't clear that there is a net loss. This is further complicated by indications that an elevated CO2 environment increases soil organic matter production. This production is due not only to the activity of plants, but also to soil microbes. And it all is affected by other environmental limits such as water and nutrients. As Philip notes, soil moisture is also a factor when it affects albedo, though this is dependent on the type of land use: fields crops have a different effect than grasslands or forests. It all depends.