Paris (AFP) Oct 6, 2010
Scientists found that a decline in the Sun's activity did not lead as expected to a cooling of the Earth, a surprise finding that could have repercussions for computer models on climate change.
The Sun's activity is known to wax and wane over 11-year cycles, which means that in theory the amount of radiation reaching Earth declines during the "waning" phase.
The new study was carried out between 2004 and 2007 during a solar waning phase.
The amount of energy in the ultraviolet part of the energy spectrum fell, the researchers found.
But, contrary to expectation, radiation in the visible part of the energy spectrum increased, rather than declined, which caused a warming effect.
The investigation, based mainly on satellite data, is important because of a debate over how far global warming is attributable to Man or to natural causes.
Climatologists say that warming is overwhelmingly due to man-made greenhouse gases -- invisible carbon emissions from coal, gas and coal that linger in the atmosphere and trap solar heat.
But a vocal lobby of sceptics say that this is flawed or alarmist, and point out that Earth has known periods of cooling and warming that are due to variations in the Sun's output.
"These results are challenging what we thought we knew about the Sun's effect on our climate," said lead author Joanna Haigh, a professor at Imperial College London where she is also a member of the Grantham Institute for Climate change.
"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."
Insisting on caution, Haigh said that if the Sun turned out to have a warming effect during the "waning" part of the cycle, it might also turn out to have a cooling effect during the "waxing" part of the cycle.
In that case, greenhouse gases would be more to blame than thought for the perceptible rise in global temperatures over the past century.
"We cannot jump to any conclusions based on what we have found during this comparatively short period," Haigh said. "We need to carry out further studies to explore the Sun's activity, and the patterns that we have uncovered, on longer timescales."
The study is published in Nature, the weekly British science journal.
Share This Article With Planet Earth
Climate Science News - Modeling, Mitigation Adaptation
Research Suggests Climate Change Target Not Safe
Exeter UK (SPX) Oct 06, 2010
An analysis of geological records that preserve details of the last known period of global warming has revealed 'startling' results which suggest current targets for limiting climate change are unsafe. The study by climate change experts at the University of Exeter has important implications for international negotiators aiming to agree binding targets for future greenhouse gas emission ta ... read more
Slow return to school for quake-hit Haiti's students|
Pakistan stability in play with flood aid: UNHCR official
Bin Laden concerned by climate, Pakistan floods: audiotape
Pakistan flood victims struggle to rebuild alone
A Step Toward Lead-Free Electronics
A Catalyst Sandwich
An Intelligent System For Maritime Surveillance
Apple faces 625 million-dollar fines over patents: report
Climate Change Affects Horseshoe Crab Numbers
Ocean Conditions Likely To Reduce Colorado River Flows During This Winter's Drought
Doppler Radars Help Increase Monsoon Rainfall Prediction Accuracy
Danube water quality controls boosted after Hungary spill
Himalayan climate change action urged
Disappearing Glaciers Enhanced Biodiversity
Argentine Congress votes to restrict mining near glaciers
Putin says Arctic must remain 'zone of peace'
Saving Tropical Forests By Valuing Their Carbon And Improving Farm Tech
Protecting biodiversity will 'help' ASEAN economies: experts
Anti-GM crop petition tops million signatures
Land Degradation And Recovery On Western Rangelands
Indonesian flash floods kill 56, dozens missing: official
Vietnam flood death toll at least 26: officials
15 killed, dozens missing in Indonesian floods: officials
Bin Laden repeats call for Pakistan flood aid: monitors
Zambia backs off threat to shut down Internet providers
UN's Ban decries shortage of troops, supplies in restive DRC
UN envoys put spotlight on Sudan conflict fears
Algeria leader loses ground in power fight
Canadian helps severely disabled speak through music
Suicide rate rises among China's elderly: state media
China marks 30 years of one-child policy
Critics urge pressure as China one-child policy hits 30
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2010 - SpaceDaily. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement|