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To: combjelly who wrote (272159)	2/5/2006 1:49:02 PM
From: longnshort	Read Replies (1) \| Respond to of 1587008

Hotter-burning sun warming the planet By Michael Leidig LONDON SUNDAY TELEGRAPH The sun is burning hotter than usual, offering a possible explanation for global warming that needs to be weighed when proceeding with expensive efforts to cut emissions of greenhouse gases, Swiss and German scientists say. "The sun has been at its strongest over the past 60 years and may now be affecting global temperatures," said Sami Solanki, the director of the renowned Max Planck Institute for Solar System Research in Gottingen, Germany, who led the research. "The sun is in a changed state. It is brighter than it was a few hundred years ago and this brightening started relatively recently — in the last 100 to 150 years," Mr. Solanski said. Average global temperatures have increased by about 0.2 degrees Celsius (0.36 degrees Fahrenheit) over the past 20 years and are widely believed to be responsible for new extremes in weather patterns. Globally, 1997, 1998 and 2002 were the hottest years since worldwide weather records were first collated in 1860. Bill Burrows, a climatologist and a member of the Royal Meteorological Society, welcomed Mr. Solanki's research. "It shows that there is enough happening on the solar front to merit further research. Perhaps we are devoting too many resources to correcting human effects on the climate without being sure that we are the major contributor," he said. Mr. Solanki said that the brighter sun and higher levels of so-called "greenhouse gases" both contributed to the change in the Earth's temperature, but it was impossible to say which had the greater impact. Most scientists agree that greenhouse gases such as carbon dioxide from fossil fuels have contributed to the warming of the planet in the past few decades, but have questioned whether other factors beyond man's control are also to blame. To determine the sun's role in global warming, Mr. Solanki's research team measured magnetic zones on the sun's surface known as sunspots, which are believed to intensify the sun's energy output. The team studied sunspot data going back several hundred years. They found that a dearth of sunspots signaled a cold period — which could last up to 50 years — but that over the past century their numbers had increased as the Earth's climate grew steadily warmer. Mr. Solanki does not know what is causing the sun to burn brighter now or how long this cycle would last. He says that the increased solar brightness over the past 20 years has not been enough to cause the observed climate changes, but believes that the impact of intense sunshine on the ozone layer and cloud cover could be affecting the climate more than the sunlight itself. David Viner, the senior research scientist at the University of East Anglia's climatic research unit, said the research showed that the sun did have an effect on global warming. He added, however, that the study also showed that over the past 20 years, the number of sunspots had remained roughly constant, while the Earth's temperature had continued to increase. This suggested that over the past 20 years, human activities such as the burning of fossil fuels and deforestation had begun to dominate "the natural factors involved in climate change," he said.

To: combjelly who wrote (272159)	2/5/2006 1:50:12 PM
From: longnshort	Read Replies (1) \| Respond to of 1587008

Sun's warming influence 'under-estimated' The Sun Opinion is divided over the Sun's impact on climate change By BBC News Online science editor Dr David Whitehouse Scientists at Armagh Observatory claim a unique weather record could show that the Sun has been the main contributor to global warming over the past two centuries. I suspect that the greenhouse lobby have under-estimated the role of solar variability in climate change Dr John Butler The weather observations, made almost daily since 1795, comprise the longest climate archive available for a single site in Ireland. Dr John Butler, the astronomer in charge of the project, told BBC News Online: "We can see global warming taking place over the past two centuries that suggests that changes in the Sun are at least partially responsible." The data will confuse some climate experts who argue that the influence of changes in the Sun on rising temperatures has already been studied, and discounted, as a major cause of global warming. Longer is better The observations at Armagh began in 1795, a few years after the observatory was founded. Temperature, pressure and, later, rainfall have been measured every day with the exception of a period around 1825. In all that time, the Armagh meteorological instruments have been moved only about 20 metres. Armagh Observatory The Armagh Observatory's weather archive spans two centuries "What makes the data so useful is that the site of the observatory has not changed all that much in 200 years," said Dr Butler. "Other weather stations have been engulfed by towns and cities that make the long-term reliability of their data questionable." When analysed, the data allow the average temperature at Armagh to be calculated to an accuracy of 0.1 deg C per decade. Eventually the entire data set will be placed on the internet. "It's quite apparent from our data that global warming, of about a degree C, has been taking place for at least a hundred years," Dr Butler told BBC News Online. Shorter is warmer The researchers point out that the mean average temperature at Armagh seems to be related to the length of the Sun's activity cycle. This cycle is on average 11 years in duration but it can vary a few years either way. "We have found that it gets cooler when the Sun's cycle is longer and that Armagh is warmer when the cycle is shorter," said Dr Butler. Scientists cannot yet fully explain how natural variations in the Sun's brightness and activity may affect the Earth's climate. While the Sun is about 0.1% brighter during shorter cycles the effect is not enough to account for the observed warming trend. "But the Sun's activity does affect the flux of cosmic rays, high-energy particles from deep space, that strike our atmosphere," said Dr Butler. Consequently it has been suggested that because cosmic rays are the main source of ionisation in the Earth's atmosphere they may have an influence on cloud formation. Solar cycle Average temperatures in Armagh appear to correlate with solar activity In general, the more cosmic rays that reach the Earth, the more low cloud there is. However, a higher solar activity leads to lower cosmic ray flux and reduced low cloud. Low clouds cool the Earth by reflecting more solar radiation back into space, so a drop in the amount of low cloud contributes to global warming. High cloud does the opposite and tends to warm the Earth by reflecting more of the Earth's infra-red radiation back to the ground. It may be that changing cloud cover has caused global warming over the past century or so. However, Dr Butler is cautious about this issue: "There is currently very little evidence for a low-altitude cloud reduction over the past century. But there is some evidence for a global increase in total cloud." "I suspect that the greenhouse lobby have under-estimated the role of solar variability in climate change," he added. "However I am not in favour of polluting the atmosphere, for whatever reason." Search BBC News Online Advanced search options Launch console BBC RADIO NEWS BBC ONE TV NEWS WORLD NEWS SUMMARY BBC NEWS 24 BULLETIN PROGRAMMES GUIDE See also: 16 Nov 00 \| Climate change Viewpoint: The Sun and climate change 14 Nov 00 \| Climate change Questioning global warming 03 Oct 00 \| Sci/Tech Climate feels the Sun's effects 03 May 00 \| Sci/Tech Sun 'minor player' in climate change Internet links: Armagh Observatory The BBC is not responsible for the content of external internet sites Top Sci/Tech stories now: Astronomy's next big thing Ancient rock points to life's origin Mobile spam on the rise Giant telescope project gets boost New hope for Aids vaccine Replace your mouse with your eye Device could detect overdose drugs Wireless internet arrives in China Links to more Sci/Tech stories are at the foot of the page.