A stronger Sun actually cools the Earth
An increase in solar activity from the Sun actually cools the Earth, suggests new research that will renew the debate over the science behind climate change.
The research overturns traditional assumptions about the relationship between the sun and global warming.
Focused on a three-year snapshot of time between 2004 and 2007, the findings will be seized upon by those who believe that man's role in rises in the earth's temperature has been overstated.
As solar activity waned at the end of one of the Sun's 11-year cycles, the new data shows the amount of light and heat reaching the Earth rose rather than fell. Its impact on melting polar ice caps, and drying up rivers could therefore have been exaggerated by conventional climate models during the period.
Scientists also believe it may also be possible that during the next upturn of the cycle, when solar activity increases, there might be a cooling effect at the Earth's surface.
However while this may support climate change sceptics' arguments in the short term, long term analysis suggests it actually provides further evidence that the heating of the planet is more than a natural, cyclical phenomenon.
Over the past century, overall solar activity has been increasing and should therefore cool the Earth, yet global temperatures have increased.
Professor Joanna Haigh, from Imperial College London, who led the study, said: "These results are challenging what we thought we knew about the sun's effect on our climate.
"However, they only show us a snapshot of the sun's activity and its behaviour over the three years of our study could be an anomaly.
"We cannot jump to any conclusions based on what we have found during this comparatively short period and we need to carry out further studies to explore the sun's activity and the patterns that we have uncovered on longer timescales.
"However, if further studies find the same pattern over a longer period of time, this could suggest that we may have overestimated the Sun's role in warming the planet, rather than underestimating it."
She denied that it would fuel scepticism about climate change research.
"I think it doesn't give comfort to the climate sceptics at all," she said. "It may suggest that we don't know that much about the Sun. It casts no aspersions at all upon the climate models."
The research, published in the journal Nature, is based on data from a satellite called SORCE (Solar Radiation and Climate Experiment) that has been measuring the sun's energy output at X-ray, ultraviolet, visible, and near-infrared wavelengths.
Professor Sir Brian Hoskins, the Director of the Grantham Institute for Climate Change at Imperial College London, said: "We know that the Earth's climate is affected both by human activity and by natural forces and today's study improves our understanding of how the Sun influences our climate.
"Studies like this are vital for helping us to create a clear picture of how our climate is changing and through this, to work out how we can best protect our planet."