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It is usually impossible to connect specific weather events to global warming. Instead, global warming is expected to cause changes in the overall distribution and intensity of events, such as changes to the frequency and intensity of heavy precipitation. Broader effects are expected to include glacial retreat, Arctic shrinkage including long-term shrinkage of the Greenland ice sheet, and worldwide sea level rise. Some effects on both the natural environment and human life are, at least in part, already being attributed to global warming. A 2001 report by the IPCC suggests that glacier retreat, ice shelf disruption such as that of the Larsen Ice Shelf, sea level rise, changes in rainfall patterns, and increased intensity and frequency of extreme weather events are attributable in part to global warming.Other expected effects include water scarcity in some regions and increased precipitation in others, changes in mountain snowpack, and some adverse health effects from warmer temperatures. Social and economic effects of global warming may be exacerbated by growing population densities in affected areas. Temperate regions are projected to experience fewer cold-related deaths but many more deaths from heat exposure. A summary of probable effects and recent understanding can be found in the report made for the IPCC Third Assessment Report by Working Group II. The newer IPCC Fourth Assessment Report summary reports that there is observational evidence for an increase in intense tropical cyclone activity in the North Atlantic Ocean since about 1970, in correlation with the increase in sea surface temperature (see Atlantic Multidecadal Oscillation), but that the detection of long-term trends is complicated by the quality of records prior to routine satellite observations. The summary also states that there is no clear trend in the annual worldwide number of tropical cyclones. |
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Lexo me shume...
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Variations in solar output have been the cause of past climate changes,but solar forcing is generally thought to be too small to account for a significant part of global warming in recent decades. Greenhouse gases and solar forcing affect temperatures in different ways. While both increased solar activity and increased greenhouse gases are expected to warm the troposphere, an increase in solar activity should warm the stratosphere while an increase in greenhouse gases should cool the stratosphere.Observations show that temperatures in the stratosphere have been cooling since 1979, when satellite measurements became available. Radiosonde (weather balloon) data from the pre-satellite era show cooling since 1958, though there is greater uncertainty in the early radiosonde record. A related hypothesis, proposed by Henrik Svensmark, is that magnetic activity of the sun deflects cosmic rays that may influence the generation of cloud condensation nuclei and thereby affect the climate. Other research has found no relation between warming in recent decades and cosmic rays. A recent study concluded that the influence of cosmic rays on cloud cover is about a factor of 100 lower than needed to explain the observed changes in clouds or to be a significant contributor to present-day climate change |
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With stunning accuracy, Rice researchers predicted the peak surge of Houston's Brays Bayou during and immediately after Ike, despite power outages that shut down the university's computing center at a critical time. "The TMC was very happy about how well the system worked and the fact that we were able to pull this off via a long-distance connection," said Phil Bedient, Rice's Herman Brown Professor of Engineering and a widely known expert on flood warning and storm surges. "They were very concerned, because if the medical center had gone under, it would have been a mess." Bedient, who with the TMC set up a real-time flood alert system in the years since Allison, saw that effort pay off during the storm. "We absolutely nailed it," he said. Having lost power at his own Houston home, Bedient spent a long night during Ike evaluating radar rainfall data coming by phone from the National Weather Service's radar through Vieux & Associates Inc. in Oklahoma and calling medical center officials with his predictions. |
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Lexo me shume...
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Noctilucent clouds, also known as night-shining clouds, were first described in 1885, two years after the massive eruption of Krakatoa, a volcanic island in Indonesia, sent up a plume of ash and debris up to 80 km into Earth's atmosphere. The eruption affected global climate and weather for years and may have produced the first noctilucent clouds. The effects of Krakatoa eventually faded, but the unusual electric blue clouds remain, nestled into a thin layer of Earth's mesosphere, the upper atmosphere region where pressure is 10,000 times less than at sea level. The clouds, which are visible during the deep twilight, are most often observed during the summer months at latitudes from 50 to 70 degrees north and south--although in recent years they have been seen as far south as Utah and Colorado. Noctilucent clouds are a summertime phenomenon because, curiously, the atmosphere at 85 km altitude is coldest in summer, promoting the formation of the ice grains that make up the clouds. |
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Lexo me shume...
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