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Climate Science News
Sun's Magnetic Cycles Influence Earth's Climate
A study published in the June 10 issue of Earth and Planetary Science Letters, shows a clear link between changes in solar magnetism and the Earth's 100,000 year climate cycles. The author, Mukul Sharma of the Department of Earth Sciences at Dartmouth College, used data of changes in the production rates of beryllium 10 to map variations in the sun's magnetic activity. "Beryllium 10 in the Earth's atmosphere depends on the galactic cosmic ray influx that, in turn, is affected by the solar magnetic activity and the geomagnetic field activity [earth's magnetic field intensity]."
When the sun is magnetically more active, it blocks incoming cosmic rays, which are charged particles that contribute to cloud formation, causing the earth to warm. When the sun is less active, more cosmic rays enter the atmosphere, increasing cloud cover, and cooling the earth.
Sharma found that changes in solar variation match changes in earth's climate. "Surprisingly, it looks like solar activity is varying in longer time spans than we realized," said Sharma. "We knew about the shorter cycles of solar activity, so maybe these are just little cycles within a larger cycle. Even more surprising is the fact that the glacial and interglacial periods on earth during the last 200,000 years appear to be strongly linked to solar activity" (www.eurekalert.org, June 6, 2002).
Conflicting Evidence on Global Glacier Trends
The great majority of the world's glaciers are retreating at rates faster than established historical rates, according to preliminary research results from a joint NASA and United States Geological Survey project to make a global assessment of glaciers. A small minority of glaciers appear to be advancing."Glaciers in most areas of the world are known to be receding," said Kargel. "But glaciers in the Himalaya are wasting at alarming and accelerating rates, as indicated by comparisons of satellite and historic data, and as shown by the widespread, rapid growth of lakes on the glacier surfaces" (http://www.spacedaily.com, June 3, 2002).
Jeff Kargel, a USGS scientist and head of the Global Land Ice Measurements from Space project, presented the results at the American Geophysical Union's recent spring meeting held in Washington.
Much ado has been made about glacier retreat in the Himalaya and many have fingered rising temperatures as the culprit. But when Robert Balling, a climate scientist at Arizona State University, checked temperature trends in the Himalaya, he found that the temperature data from January 1876 to December 1998, available through the United Nations' Intergovernmental Panel on Climate Change, shows a statistically insignificant cooling of 0.04 degrees C for the region.
Kargel went on to warn that accelerating climate change could have significant direct impacts on the rate of glacier retreat and that this could have serious political and economic consequences.
Other research published in the March 1 issue of Progress in Physical Geography shows a different picture from the one presented by Kargel. The study, by Roger Braithwaite of Manchester University, "reviews measurements of glacier mass balance in the period 1946-95."
Although there are data for 246 glaciers worldwide, most of the records are quite short, says Braithwaite. Moreover, the available data are heavily concentrated in Western Europe, North America and the former USSR, and in wetter conditions with too few data from dry-cold glaciers typical of many regions. Given the poor quality of much of the data, it is difficult to get a complete picture of global trends.
Nevertheless, the available data show that, "There are several regions with highly negative mass balances in agreement with a public perception of 'the glaciers are melting,' but there are also regions with positive balances." Braithwaite concludes, "There is no sign of any recent global trend towards increased glacier melting, and the data mainly reflect variations within and between regions."
Rain a Major Factor in Carbon Sinks
One of the major uncertainties that has plagued scientists is what happens to large amounts of the carbon dioxide emitted into the atmosphere. About 10 to 30 percent of all carbon dioxide emitted in the United States, for example, is being absorbed by the mainland's ecosystem and the amount is steadily increasing. At least one study has estimated that North America fully absorbs its carbon dioxide emissions.
Some explanations of the increasing rates of carbon absorption focus on forest regeneration in formerly logged areas, increased plant growth and even higher temperatures. Geophysical Research Letters has published in its March 28 issue a study that argues that the single most important factor for accelerated carbon absorption is the documented increase in rainfall and humidity in the U.S., which increases plant growth.
The researchers focused on climate data from 1950 to 1993. Using a computer model, they found that even including all other possible factors that may influence plant growth, increases in rainfall account for two-thirds of the additional plant growth. The researchers determined that increased rainfall during the study period led to a 14 percent increase in plant growth.
As has become typical of global warming research, there is a dark cloud for every silver lining. According to an article about the study in Science (June 7, 2002), "The new findings might mean that proposals to counteract global warming by planting forests are over naïve. Planting trees is well and good," says Steven Running at the University of Montana and one of the study's co-authors. "But the trees' effectiveness as carbon sinks will depend on rainfall - which could suddenly reverse its trend and decrease. Perhaps rainfall will continue increasing with global warming, but if that doesn't happen," Running cautions, "we could lose a lot of carbon sink strength very quickly."
Pity Poor Tuvalu - It's Not Sinking
Tuvalu, the tiny island nation that has become the poster child of global warming catastrophe, has had its bluff called. The government of Tuvalu claims that its people, as well as peoples from other small island nations, are in danger of losing their homes due to rising sea levels cause by manmade global warming.
In 1993, the National Tidal Facility in Adelaide, Australia installed a tide gauge in Funafuti, Tuvalu, which "has been returning high resolution, good scientific quality data since March 1993." The measurements show that during the nine years there has been a increase in sea level of 0.9 mm per year. The NTF notes, that, "A major anomaly occurred in 1998 in response to an El Niño that lowered sea levels by 35 cm in March and April of that year. By November 1998, sea level had completely recovered and resumed its normal seasonal cycle that typically exhibits about a 10 cm rise early in the calendar year followed by about a 10 cm sea level drop relative to average sea level for the latter part of the year."
A historical assessment of sea level change in Australia and the Pacific from 1978 to 1999, "shows a very similar sea level behavior at Funafuti," showing a sea level rise of 0.07 mm per year. "The historical record shows no visual evidence of any acceleration in sea level trends" (http://www.ntf.flinders.edu.au).
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