Climate Change from Solar Change: the Door Is Closed
19 Jul, 2007 01:21 pm
Mike Lockwood is a specialist on long term trends in solar data. He explains how the Sun does not play a role in climate change.
What were the findings?
Yes, to recent climate change. We examined all the outputs of the Sun that have been postulated in serious ways, that is that the Sun could influence our climate. The main two which are the power that we get in the form of heat and light, and also the magnetic fields that come out of the Sun and shield us from cosmic rays - they have been postulated to have an affect on clouds.
If you go back to pre-industrial times there is very good evidence of such effect. But in recent times we showed that these outputs had turned in the wrong direction and have declined since about 1985 or 1987, depending on which of the two you are talking about. We would have therefore expected, if changes in the Sun had been a major driving factor in climate change, a response in the Earthís temperature within about 4 years. But the onset of the response is much quicker than that.
Essentially, if you take long term averages to get rid of fluctuations in our climate system, the El Ninos and the like, and if you smooth out the long-term trend, you find that it carried on upwards and took no notice of the Sun changing direction whatsoever. Therefore we can put very low limits on any possible contribution to climate change from solar change.
How was the research conducted?
The idea was to use data in as a straightforward way as possible without recourse to complicated climate models, because skeptics say, Ďwe donít believe the models and suchí.
We tried to remove from the solar data the well known 11 year oscillation because of the sunspot cycle. Then looking at underlying trends once youíve taken the cycle out. Then we treated the temperature data in exactly the same way so that one could still compare light with light. That lead to a seedy underline trend, which was how we were able to identify that 1985 had been a high point in solar activity and has declined since then. And these outputs that could have affected the Earth, possibly, by some theories, could have actually been going in the wrong direction since then. The only way out is to postulate that there is some enormously long lag: it takes twenty years for the Earth to respond to this. Iím afraid this is nonsense. Knock out a bit of sunlight with volcanic haze, you will see the effects in a year or two. Therefore it is not valid at all.
Does this research close the door on the climate change debate?
Yes it does. If Iím absolutely honest, it was closed already. I think it was difficult for people who werenít trained in climate science to understand the evidence, because it was complicated and very technical. The idea was that this was a very simple demonstration that you couldnít just pin it on the Sun as increasingly global warming skeptics have been trying to do.
You think it would be the end. Unfortunately, itís amazing how misrepresentation can carry on. A lot of people have picked on the idea that global warming has stalled, because recent temperatures havenít risen in quite the same way as before. This is very much cherry picking the evidence. They are ignoring the fact that the long-term trend is steadily going upwards. They are picking the fluctuations that exist naturally in our climate system and those that suit them, which is an astonishing cherry picking of the evidence.
Interview by: Christopher Le Coq
Mike Lockwood is a researcher at the Rutherford Appleton Laboratory in the
Space Science and Technology Department and a professor at the Southampton University in the Department of Physics and Astronomy in the United Kingdom