A group of scientists from the Scripps Institution of Oceanography (TSIO) at the University of California at San Diego analyzed cloud patterns and found that they are moving toward the poles and are getting taller, as predicted by climate models. These changes are provoked by climate change which could be making climate change worse. Clouds and climate change have a delicate relationship, and any alteration could start and endless cycle of consequences.
Clouds are a key point in the climate problem and according to climatologist Veerabhadran Ramanathan of TSIO, who was not involved in the research, clouds influence the climate, and they are affected by it. Their behavior has been a mystery for scientists that have tried to understand current climate and forecast future trends.
Clouds act as reflectors since they bounce incoming sunlight back into space. Also, they absorb heat emitted from the surface and the radiate it back down.This complex relationship makes it hard for scientists to understand the effects of clouds on climate and vice versa.
Evidence for Climate Change in the Satellite Record is the name of the study, and it was published Monday, July 11, in the Journal Nature. NOAA, the U.S. Department of Energy Office of Science, and Nasa supported the study, and researchers from the University of California Riverside, Lawrence Livermore National Laboratory, and Colorado State University are co-authors.
The study made by the team from the Scripps Institution of Oceanography used satellite cloud records to track cloudy storms movements on Earth, but Joel Norris, an atmospheric scientist, also at Scripps, and lead author on the study, says that satellites were not made to monitor clouds, and the data was not clear.
Geostationary satellites might underestimate cloudiness because they look directly down to the planet and clouds are easier to detect on a slanted path. Polar-orbiting satellites are designed to cross the same spot at the same time each day, which is beneficial for tracking clouds, but the eventually run low on fuel and they may drift in their orbits, making them arrive a bit late every day, Science reports.
Norris and his team corrected these alterations in cloud data records from 1983 to 2009. Then, the scientists analyzed the corrected data for bright, long patterns and they found them. Their research shows that since the 1980s, the world is cloudier toward the poles and less cloudy in the midlatitudes. The data also found that thunderclouds are moving up, and dry subtropical regions are expanding.
Bjorn Stevens, a meteorologist of the Max Planck Institute for Meteorology in Hamburg, Germany, stated that the study also reveals how inadequate are the cloud observing systems when it comes to fundamental climate questions. Science quotes Stevens who says that this work is a reminder for those who want to understand climate change because it is necessary to do a better job to watch clouds.
The study is the first one to confirm that models have correctly predicted cloud patterns
Scientist compared simulations of climate change from 1983 to 2009 and what was surprising is that the results matched three patterns of those climate model predictions.
The models anticipated that storm tracks – the paths that cyclones travel in the Northern and Southern hemispheres- would go to the poles. The tops of the highest clouds would get even higher and subtropical regions would increase in size, Science reports.
Norris explains that storm clouds are essential to keep the planet cool by reflecting heat back to space, but their impact is not significant if they are farther north or south, where solar radiation is not a problem. Science says that dry, cloud-free areas at lower latitudes mean more absorbed radiation on Earth, and higher clouds tops create a blanket effect on greenhouse gasses.
Another thing that was discovered in the research is that there were to phenomena that influenced climate during the period studied. There were two major volcanic eruptions, Mexico’s El Chichon in 1982 and the Philippines´ Pinatubo in 1991. Both volcano activities cooled and then warmed the climate.
The simulation models showed that warming produced similar cloud patterns to warming caused by greenhouse gasses, which means that nature also contributed to the current climate change. Norris says that further research to identify how much the volcanos and the greenhouse gas has contributed to the ongoing clouds changes is part of plans.
But even if the study was revealing, a significant number of questions are still not answered. Science says that Stevens, who is also a lead author on the “Clouds and Aerosols” chapter of the Intergovernmental Panel on Climate Change’s Fifth Assessment Report, stated -as Norris noted- that it’s hard to distinguish between greenhouse gas effect and volcano effects in the study’s period. He added that the study does not point out the types of clouds that are thought to be crucial for future warming, as low-lying clouds over subtropical oceans, which have a cooling effect that might be dissipating as the world warms.