Ozone Alert
alexander hamp
surface temperature data, reports a team of scientists from the
National Oceanic and Atmospheric Administration's National Climatic
Data Center in Asheville, N. C.
Led by the center's Senior Scientist Tom Karl, the team analyzed
temperatures from around the globe during the years 1900 to 1997 and
back to 1880 for land areas. For 1997, land and ocean temperatures
averaged three-quarters of a degree Fahrenheit above normal. (Normal
is defined by the mean temperature, 61.7 degrees F, for the 30-years
1961-90.) The 1997 figure exceeds the previous record warm year, 1990,
by 0.15 degrees Fahrenheit.
The record-breaking warm conditions of 1997 continues the pattern of
very warm global temperatures. Nine of the past eleven years have been
the warmest on record.
"Land temperatures did not break the previous record set in 1990, but
1997 was one of the five warmest years since 1880," said Karl.
Including 1997, the top ten warmest years over the land have all
occurred since 1981, and the warmest five years all since 1990. Land
temperatures for 1997 averaged three-quarters of a degree above
normal, falling short of the 1990 record by one-quarter of a degree.
Ocean temperatures during 1997 also averaged three-quarters of a
degree above normal, which makes it the warmest year on record,
exceeding the previous record warm years of 1987 and 1995 by 0.3 of a
degree Fahrenheit.
With the new data factored in, global temperature warming trends now
exceed 1.0 degree Fahrenheit per 100 years, with land temperatures
warming at a somewhat faster rate. "It is likely that the sustained
trend toward increasingly warmer global temperatures is related to
anthropogenic increases in greenhouse gases," Karl said.
GLOBAL WARMING: SPRING ARRIVING EARLIER Satellites Show Global Warming
May Be Changing The Seasons
A new study of satellite photos shows that between 1981 and 1991,
plants in northern climates started their springtime spurt of growth a
full week earlier, and that global warming may be responsible. For
migratory birds and other animals that depend on the timing of plants
for food, this change could have deadly consequences.
The report, based on an analysis of satellite data, shows dramatic
changes in plant growth across a vast swath of the Northern
Hemisphere. In the 10 years from 1981 to 1991, the start of the plant
growth cycle that accompanies the spring thaw appeared to leap ahead
by an average of eight days. The cause is unknown, but the timing "is
consistent with an enhanced greenhouse effect caused by the build-up
of . . . gases in the atmosphere," said the report by Boston
University climatologist Ranga Myneni and four colleagues.
Excerpted from the New York Times, August 4, 1996 WASHINGTON, Aug, 3
(AP) - Ultraviolet radiation which causes skin cancer and cataracts in
humans, has increased over large regions of the earth in the last 15
years as ozone in the atmosphere has decreased, a new study says.
Ozone, found in the atmosphere between the earth's surface and
altitude of 37 miles, absorbs much of the sun's radiation. But it is
depleted through complex chemical reactions, some from man-made
chlorofluorocarbons used in refrigeration, electronics and insulating
materials.
The ozone depletion has been sharply reduced in recent years through
international agreements curbing chlorofluorocarbon emissions. But the
new study, based on analysis of data from an instrument that is flown
aboard NASA'S Nimbus-7 satellite, found that the annual average amount
of UV-B, the portion of the ultraviolet spectrum that causes the most
damage, had increased at a rate of 9.9 percent a decade at the
southernmost parts of Argentina and Chile.
The rate of increase has been about 4 percent a decade for areas near
the United States-Canadian border, and 6.8 percent for Britain,
Germany, Russia and Scandinavia.
"The increases are largest in the middle and high latitudes, where
most people live and where the majority of the world's agricultural
activity occurs," said Dr. Jay R. Herman, an atmospheric scientist at
the National Aeronautics and Space Administration's Goddard Space
Flight Center in Maryland.
Scientists consider the risks of further increases in ultraviolet
radiation to be serious. Long-term exposure to UV-B from the sun is
associated with two kinds of skin cancer - basal cell and squamous
cell carcinomas - and is responsible for other harmful effects in
humans, to the skin, the eyes and the immune system. It also harms
some crops and interferes with marine life.
Source: http://www.thegreeno.com/green-articles/global-warming-articles/ozone-alert.html