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 Interactions with aerosols boost warming potential of some gases For decades, climate scientists have worked to identify and measure key substances -- notably greenhouse gases and aerosol particles -- that affect Earth's climate. Do dust particles curb climate change? A knowledge gap exists in the area of climate research: for decades, scientists have been asking themselves whether, and to what extent man-made aerosols, that is, dust particles suspended in the atmosphere, enlarge the cloud cover and thus curb climate warming. Ozone layer depletion levelling off By merging more than a decade of atmospheric data from European satellites, scientists have compiled a homogeneous long-term ozone record that allows them to monitor total ozone trends on a global scale - and the findings look promising. Water in a changing climate New research announced at the international Water in a changing climate science conference in Melbourne 24-28 August, implicates pollution from Asia, Europe and North America as a contributor to recent Australian rainfall changes. The greenhouse gas that saved the world When Planet Earth was just cooling down from its fiery creation, the sun was faint and young. So faint that it should not have been able to keep the oceans of earth from freezing. But fortunately for the creation of life, water was kept liquid on our young planet. The Sky Is Not Falling: Pollution in eastern China cuts light, useful rainfall New research shows that air pollution in eastern China has reduced the amount of light rainfall over the past 50 years and decreased by 23 percent the number of days of light rain in the eastern half of the country. Missing Link to Cloud Formation Found New chemical research shows how cloud seedlings form over forested areas. Scientists expect wildfires to increase as climate warms in the coming decades As the climate warms in the coming decades, atmospheric scientists at Harvard's School of Engineering and Applied Sciences (SEAS) and their colleagues expect that the frequency of wildfires will increase in many regions. Jupiter pummeled, leaving bruise the size of the Pacific Ocean Something slammed into Jupiter in the last few days, creating a dark bruise about the size of the Pacific Ocean. World's largest aerosol sensing network has leafy origins Twenty years ago, Brent Holben was part of a NASA team studying vegetation from space. In an unlikely career twist, his research morphed into the study of a critical, if overlooked, subplot in the story of climate change. More Aerosols Current Events and Aerosols News Articles |
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