Mon, Apr 27, 2009 page9

• The unexplored factor in climate change: clouds

  Using powerful computer technology and satellite data, scientists at a lab in Delft hope to gain a more accurate picture of how clouds affect changing temperatures

  • By Catherine Hornby / REUTERS
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  Wearing 3D viewing goggles, scientists peer at virtual pink, blue and purple clouds billowing in cyberspace at a research laboratory in the Dutch city of Delft.

  By tracking how particles move in and around computer-simulated clouds, they hope to shed light on one of the unknowns of climate forecasting: how these masses of water droplets and ice crystals influence changing temperatures.

  The research, at Delft University of Technology, was undertaken because of the growing urgency for scientists to improve ways of forecasting climate change.

  In addition to the Dutch scientists’ work, a multimillion-euro satellite project funded by the European and Japanese space agencies will be launched shortly to help demystify clouds, which are also a source of inspiration for thousands of amateur cloud-spotters who post their comments and photos online.

  Researcher Thijs Heus, a former student at the laboratory, said he used the simulations to chart data such as the speed, temperature and lifespan of clouds.

  “We number the clouds and we track them from their infancy through their entire life cycle,” he said.

  “We can also give them color to see if dust particles are moving up or down within and around the clouds,” Heus said, demonstrating ways to observe clouds in more detail by magnifying their virtual images on screen.

  Using powerful computer technology and satellite data, the scientists at Delft hope to gain a more accurate picture of how clouds react to climate change.

  “There is enormous uncertainty about what clouds will do and how they will respond to a changing climate and that is a major impediment for climate predictions,” said Harm Jonker, associate professor at the university.

  Projections of how much the earth’s temperature will rise in the next century vary from 1.1°C to 6.4°C, with the effect of clouds remaining one of the main sources of uncertainty, the UN Climate Panel found in its 2007 climate assessment report.

  Jonker said it was unclear, for example, whether there would be more or fewer low clouds, such as cumulus clouds, in warmer conditions, which would affect the rate of global warming because of their role in reflecting sunlight away from the earth.

  “In a warmer climate, if there is more evaporation, that could lead to more of the lower clouds, which could diminish the effects of climate warming,” Jonker said.

  He said warm air could hold more water vapor than cold air before it formed clouds, so there might be fewer low clouds as the earth heated up, which would accelerate global warming.

  Rising sea levels and increased risk of droughts, flooding and species extinction are some of the likely effects of global warming, caused mainly by emissions of greenhouse gases from burning fossil fuels, the UN Climate Panel has projected.

  European and Japanese space scientists have turned their attention to clouds because of the pressing need for research.

  A satellite project due for launch in 2014 aims to improve understanding of the role they play in climate regulation.

  The project, known as EarthCARE, is being assembled mainly by the Astrium unit of the European aerospace group EADS and combines the technology of existing cloud observation satellites with new instruments for a more accurate picture.

  “It’s much more complex than anything that’s flying at present,” said Stephen Briggs, head of the Earth Observation, Science, Applications and Future Technologies Department at the European Space Agency.

  “The difficulty with clouds is that you can’t see into them, so you have to find ways of looking into their three-dimensional structure, such as with radar systems,” Briggs said.

  Advances in research are followed closely by cloud enthusiasts who spend their leisure time looking out for unusual varieties and learning about their effect on the planet.

  “We believe that clouds are unjustly maligned and that life would be immeasurably poorer without them,” says the Cloud Appreciation Society, a club for spotters, on its Web site, where it regularly posts a “cloud of the month.”

  The wispy high cirrus, the ominous cumulonimbus and the fluffy cumulus have all held the title and have been the subject of heated debate in Internet chat forums.

  Thousands of people capture unusual or striking clouds on camera and share them online.

  “High cirrus thickened up to put on a strange show over Phoenix this evening,” US cloud spotter Mike Lerch wrote on an online chat forum before posting dramatic shots of the spidery high clouds in the skies above Arizona.

  Enthusiasts are keen to challenge negative attitudes to clouds, which have spawned sayings such as “a dark cloud on the horizon” and “even the darkest cloud has a silver lining.”

  “I thought it was about time someone stood up for the clouds because too many people complain about them,” said Gavin Pretor Pinney, author of The Cloudspotter’s Guide. “They are rather chaotic things, difficult to predict, difficult to fully understand, but the facts are emerging that they play a crucial and essential role in regulating and affecting the temperatures on the planet.”
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