Sun 'not a factor in climate change'
Wednesday, 11 Jul 2007 09:31
The Sun is not responsible for modern global warming, say researchers
Science In Focus
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Claims by climate change sceptics that the Sun is responsible for rising temperatures on Earth have been rejected in a new research paper.
The article, published in the Royal Society's journal Proceedings A, stresses that while cosmic rays may have had some impact upon the world's climate in the past, variations in the Sun's output cannot be held responsible for global warming.
In releasing their findings, researchers have countered the argument put forward by those who reject the idea that humans are causing world temperatures to rise as a result of rising carbon dioxide emissions created by their activities.
The alternative hypothesis that solar changes are actually to blame for climate change was featured in the Channel 4 documentary, The Great Global Warming Swindle, earlier this year.
But authors of the new paper say they have discovered that while the Sun's output has declined over the past 20 years, temperatures on Earth have risen.
Mike Lockwood, from the Rutherford-Appleton Laboratory in Oxfordshire, and fellow researcher Claus Froehlich, from the World Radiation Centre in Switzerland, subsequently argue that the Sun is not a factor in recent climate change.
They reached their conclusion after comparing solar output and the intensity of cosmic rays over the past 30 to 40 years with the average global surface temperature recorded over the period.
While acknowledging the fact that the Sun "may well" have been a factor in post-industrial climate change during the first half of the 20th century, they argue that "over the past 20 years, all the trends in the Sun have been in the opposite direction to that required to explain the observed recent and rapid rise in global mean temperatures".
Presenting their findings, the researchers write: "Hence, irrespective of any connections between the Sun and Earth's climate before the dominance of the effects of burning fossil fuels, the Sun is not a factor in recent climate change."