Geoengineering
[Due to the increasing size of the archives, each topic page now contains only the prior 365 days of content. Access to older stories is now solely through the Monthly Archive pages or the site search function.]
Aerosols Can Either Increase or Decrease Rainfall Based on Local Environmental Conditions
September 07, 2008
|
| Evolution of deep convective clouds developing in the pristine (top) and polluted (bottom) atmosphere. Click to enlarge. Source: AAAS |
An international team of scientists, headed by Prof. Daniel Rosenfeld of the Institute of Earth Sciences at the Hebrew University of Jerusalem, has concluded that air pollution can either increase or decrease rainfall, depending on local environmental conditions. The determination of this issue is one with significant consequences in an era of climate change and specifically in areas suffering from manmade pollution and water shortages, including Israel, according to the researchers. A paper on the work appears in the 5 September issue of the journal Science.
Aerosols serve as cloud condensation nuclei (CCN) and thus have a substantial effect on cloud properties and the initiation of precipitation. Large concentrations of human-made aerosols have been reported to both decrease and increase rainfall as a result of their radiative and CCN activities. At one extreme, pristine tropical clouds with low CCN concentrations rain out too quickly to mature into long-lived clouds. On the other hand, heavily polluted clouds evaporate much of their water before precipitation can occur, if they can form at all given the reduced surface heating resulting from the aerosol haze layer.
More... | Comments (2) | TrackBack (0)
Injecting Sulfate Particles into Stratosphere Could Have Drastic Impact on Earth’s Ozone Layer
April 25, 2008
 |
| Earth’s ozone hole, shown in blue, could be exacerbated by some geoengineering efforts to mitigate climate change. Click to enlarge. Credit: NASA |
A much-discussed geoengineering approach to offset global warming by injecting sulfate particles into the stratosphere would have a drastic impact on Earth’s protective ozone layer, according to a new study led by Simone Tilmes of the National Center for Atmospheric Research (NCAR) in Boulder, Colo.
The research concluded that such an approach would delay the recovery of the Antarctic ozone hole by decades and cause significant ozone loss over the Arctic. The ozone layer is critical for life on Earth because it blocks dangerous ultraviolet radiation from the Sun.
