Is It The Sun Wot Done It?
Thursday, 21 April 2011 17:35 Dr. David Whitehouse
If you are not confused about the Sun’s (the star that is not the newspaper as alluded to by the headline) role in influencing the Earth’s climate then perhaps you haven’t been paying attention recently.
It is a common story in climate change science. Some researchers will offer definitive statements that the Sun couldn’t possibly be responsible to any significant degree in the recent warm period the Earth has experienced. Look behind such comments however and you will find that the science, as science often is, is more equivocal, as a few recent papers indicate. There is much food for thought.
The common view is that the Sun did have a majority influence up until about 1950 – 60, but since then, because of forcing from greenhouse gasses, its role has been miniscule.
Miniscule globally that is. Regionally it might be a very different matter. Solar scientists have been going on about this for years. The speculation is that the Sun’s influence could be significant regionally such as across, say, Europe in winter, but not significant globally. However, one does wonder how many local regions are needed to be present before such a solar effect might become more global?
We all know of the way solar activity has been at a very high level in the past century. Solar activity peaked in the mid 1950’s and mid-1980’s and then declined (some researchers conveniently like to ignore the 1980’s peak and just focus on the 1950’s one). Solar activity was rising throughout the 20th Century at just the same time that the Earth’s annual average temperature increased, rising steadily with some standstills until about 2000 when it has remained static at the warmest level in the instrumental period (since 1860).
Add to this the observations that show when solar activity was low in the 17th century – when for decades there were hardly any sunspots to be seen – there was a coincident period called the Little Ice Age, and when solar activity was low for a decade or two at the start of the 19th century (the so-called Dalton Minimum) the Earth also chilled slightly has led some to speculate that there is a connection.
Low solar activity, cool earth: High solar activity, warm Earth? There must be a connection because all these correlations are straining explanation by chance. The problem is that no one has come up with a physical mechanism whereby the Sun and climate are linked in a convincing way. It doesn’t seem that solar modulation of Cosmic Rays affecting cloudiness can do it. So what is going on? (GWPF)