February 12, 2007
You were hoping for an erudite discussion of one of the works of Aristophanes? Not today. Instead we are going to look at how clouds and cosmic rays influence our weather and more importantly, climate.
Every one who has looked into the subject knows that climate science is no longer much about science. It is about politics.
When politicians and journalists declare that the science of global warming is settled, they show a regrettable ignorance about how science works. We were treated to another dose of it recently when the experts of the Intergovernmental Panel on Climate Change issued the Summary for Policymakers that puts the political spin on an unfinished scientific dossier on climate change due for publication in a few months' time. They declared that most of the rise in temperatures since the mid-20th century is very likely due to man-made greenhouse gases.I was a global warming sceptic once. Now I'm a believer. Given the fact that we have a lot of evidence that other planets in our solar system are heating up as well, I'm not convinced that the global warming the Earth is experiencing is man made.
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.Solar output has increased about 0.5% over the last 100 years according to the latest estimates.
The best measurements of global air temperatures come from American weather satellites, and they show wobbles but no overall change since 1999.A strictly radiation accounting shows that increased solar output accounts for about 60% of the global warming of the last 100 years. What could account for the other 40% if not man?
Well we have a new candidate. Cosmic rays. Or the lack of them actually.
Disdain for the sun goes with a failure by the self-appointed greenhouse experts to keep up with inconvenient discoveries about how the solar variations control the climate. The sun's brightness may change too little to account for the big swings in the climate. But more than 10 years have passed since Henrik Svensmark in Copenhagen first pointed out a much more powerful mechanism.So it would appear that increased solar output comes with an amplifying mechanism. Cosmic rays and clouds.
In Global Cooling I looked into how the sun powers our short term climate cycles. Longer term climate cycles appear to be driven by orbital mechanics such as the roundness of Earth's orbit around the sun and global wobble which changes the angle the Earth presents to the sun. Those are well known and are called Milankovitch Cycles.
There is another factor which needs attention. The Earth's magnetic field waxes and wanes. Currently we are in a waning phase. It has declined about 10% in the last 160 years.
I suppose that will give "the sky is falling" folks something new to be scared to death about and some new reason for them to declare that we have to raise taxes to have the money to fix the problem.
Some things never change.
You can read more about clouds, cosmic rays, and climate change at The U.K. Telegraph
Update: 13 Feb '007 1053z
Donalds Sensing discusses the issue with lots of charts, graphs, and pretty pictures of the sun.
Cross Posted at Power and Control
posted by Simon on 02.12.07 at 11:11 AM
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