Science paper examines role of aerosols in climate changeSeptember 08, 2008A group of scientists affiliated with the International Geosphere-Biosphere Programme (IGBP) have proposed a new framework to account more accurately for the effects of aerosols on precipitation in climate models. Their work appears in the 5 September issue of Science magazine. The increase in atmospheric concentrations of man-made aerosols-tiny particles suspended in the air-from such sources as transportation, industry, agriculture, and urban land use not only poses serious problems to human health, but also has an effect on weather and climate. Recent studies suggest that increased aerosol loading may have changed the energy balance in the atmosphere and at the Earth's surface, and altered the global water cycle in ways that make the climate system more prone to precipitation extremes.
It appears that aerosol effects on clouds can induce large changes in precipitation patterns, which in turn may change not only regional water resources, but also may change the regional and global circulation systems that constitute the Earth's climate. The proposed framework improves scientists' ability to simulate present and future climates by integrating, for the first time, the radiative and microphysical effects of aerosols on clouds. The radiative effects of aerosols on clouds mostly act to suppress precipitation, because they decrease the amount of solar radiation that reaches the land surface, and therefore cause less heat to be available for evaporating water and energizing convective rain clouds. Microphysical effects of aerosols can slow down the conversion of cloud drops into raindrops, which shuts off precipitation from very shallow and short-lived clouds. Model simulations suggest that this delay of early rain causes greater amounts of cloud water and rain intensities later in the life cycle of the cloud. This suggests that rain patterns are shifting, leading to possible drought in one area and flooding downwind in another area. In addition, greater cooling below and heating above leads to enhanced upward heat transport. Model simulations have shown that greater heating in the troposphere enhances the atmospheric circulation system, shifting weather patterns due to changes convective activity. Investigations of aerosol/precipitation effects are especially relevant to policy issues, as effects on the hydrological cycle may affect water availability, a great concern in many regions of the world. The IPCC, in its latest climate change assessment report, declared aerosols to be "the dominant uncertainty in radiative forcing (a concept used for quantitative comparisons of the strength of different human and natural agents in causing climate change)". Therefore, aerosols, clouds and their interaction with climate are still the most uncertain areas of climate change and require multidisciplinary coordinated research efforts. To that end, authors of the Science article are participating in a new, international research project designed to study the connections between aerosols, clouds, precipitation and climate (ACPC project). The project will bring together an international multidisciplinary group of scientists from the areas of aerosol physics and chemistry, cloud dynamics, and cloud microphysics under theauspices of two international research programmes, the International Geosphere-BiosphereProgramme (IGBP) and the World Climate Research Programme (WCRP). International Geosphere-Biosphere Programme | |||||||||||||||||||||
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Related Aerosols Current Events and Aerosols News Articles VAMOS Ocean Cloud Atmosphere Land Study The clouds being investigated in this study are known as marine stratocumulus clouds. They tend to form adjacent to continents where deep, cold, upwelling water reaches the sea-surface. Brookhaven Scientists Take Off for Southeastern Pacific Climate Study During October and November 2008, some 150 scientists from 40 institutions in eight nations - including scientists from the U.S. Department of Energy's (DOE) Brookhaven National Laboratory - will take part in an international field experiment designed to make observations of critical components of the climate system of the southeastern Pacific. International Field Campaign examines impact of beetle kill on Rocky Mountain weather, air quality Mountain pine beetles appear to be doing more than killing large swaths of forests in the Rocky Mountains. Scientists suspect they are also altering local weather patterns and air quality. Pine Bark Beetles Affecting More than Forests Pine bark beetles appear to be doing more than killing large swaths of forests in the Rocky Mountains. Scientists suspect they are also altering local weather patterns and air quality. IMPACTS: On the Threshold of Abrupt Climate Changes Abrupt climate change is a potential menace that hasn't received much attention. That's about to change. Through its Climate Change Prediction Program, the U.S. Department of Energy's Office of Biological and Environmental Research (OBER) recently launched IMPACTS - Investigation of the Magnitudes and Probabilities of Abrupt Climate Transitions - a program led by William Collins of Berkeley Lab's Earth Sciences Division (ESD) that brings together six national laboratories to attack the problem of abrupt climate change, or ACC. Tracking Down the Menace in Mexico City Smog A new report by scientists who are part of the international MILAGRO Campaign indicates that some of the most harmful air pollution in Mexico City may not come from motor vehicles but instead originates with industrial sources - and that the culprit may be garbage incineration. Dirty air brings rain -- then again, maybe not An international team of scientists, headed by Prof. Daniel Rosenfeld of the Institute of Earth Sciences at the Hebrew University of Jerusalem, has come up with a surprising finding to the disputed issue of whether air pollution increases or decreases rainfall. The conclusion: both can be true, depending on local environmental conditions. NASA study improves ability to predict aerosols' effect on cloud cover Using a novel theoretical approach, researchers from NASA and other institutions have identified the common thread that determines how aerosols from human activity, like the particles from burning of vegetation and forests, influence cloud cover and ultimately affect climate. Scientists to Assess Beijing Olympics Air Pollution Control Efforts As the Summer Olympics in Beijing kicks off this week, the event is giving scientists a once-in-a-lifetime opportunity to observe how the atmosphere responds when a heavily populated region substantially curbs everyday industrial emissions. NIST trumps the clumps: Making biologic drugs safer Scientists at the National Institute of Standards and Technology (NIST) have developed a technique to measure the formation of clumps of proteins in protein-based pharmaceuticals. More Aerosols Current Events and Aerosols News Articles |
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