August 2007
Global Warming And Solar Activity
A new study has recently silenced one of the global warming sceptics’ “big-guns” in the battle over climate change. The news comes in the wake of a recent documentary suggesting that global warming was responsible in large part to solar activity. Professor Mike Lockwood of the Rutherford Appleton Laboratory in Oxfordshire authored the report and stated that it would “put another nail” in the coffin of such theories.
Scientists analysed data of the sun’s output in the last 25years of the 20th century as the basis for the report, which shows that sun activity has been declining since 1985 whilst conversely, global temperatures continued to rise at a rapid rate.
As far as some of the direct effects of solar cycles on the earth’s climate go, about once every 11 years changes in the Sun's magnetic field result in increases in the number and magnitude of sunspots and solar flares, which bombard Earth with charged particles. During times of high activity, like in year 2000, the Sun shines about 0.07 percent brighter.
However, although events such as sunspots have increased in the last 400 years, according to Tom Wigley of the National Center for Atmospheric Research, their effect only contributed a small amount to global warming.
"Our results imply that, over the past century, climate change due to human influences must far outweigh the effects of changes in the Sun's brightness."
Professor Lockwood is also adamant in disproving the solar activity – climate change thesis in his report.
"The temperature record is simply not consistent with any of the solar forcings that people are talking about. They changed direction in 1985, the climate did not… [the temperature] increase should be slowing down but in fact it is speeding up."
The majority of the scientific community have welcomed these findings as providing valuable evidence against green house gas "deniers". James Hansen, a Nasa climate scientist who was once censured by the Bush administration for his outspoken stance on global warming regards such solar-warming links as outdated. He was emphatic in commenting on the paper
"The reason [this paper] has value is that the proponents of the notion that the sun determines everything come up with various half-baked suggestions that the sun can somehow cause an indirect forcing that is not included in the measurements of radiation coming from the sun. These half-baked notions are usually supported by empirical correlations of climate with some solar index in the past. Thus, by showing that these correlations are not consistent with recent climate change, the half-baked notions can be dispensed with."
However, leading sceptic Nir Shaviv, an astrophysicist at the Hebrew University in Jerusalem, has attempted to defend the solar – global warming connection. Theorising that changes in solar activity would require a number of years to be fully reflected in conditions on earth, he has proposed a time-lag effect, thus accounting for discrepancies in the data. In spite of this, Professor Lockwood is highly sceptical of such an explanation: "nobody has invoked that kind of lag before. It’s only been invoked now as a way out." Indeed, even if the lag was of a magnitude of 50years, we would already be able to see the rise in global temperatures slowing.
The NASA Goddard Institute for Space Studies (GISS) agree with this, stating: "...the solar increases do not have the ability to cause large global temperature increases...greenhouse gases are indeed playing the dominant role."
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