Oceans, greenhouse gases rising faster: reports
Oceans, greenhouse gases rising faster: reports
By Susan Heavey Thu Nov 24, 2:04 PM ET
http://news.yahoo.com/s/nm/20051124/sc_nm/science_warming_dc
WASHINGTON (Reuters) - Ocean and so-called greenhouse gas levels are
rising faster than they have for thousands of years, according to two
reports published on Thursday that are likely to fuel debate on global
warming.
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One study found the Earth\'s ocean levels have risen twice as fast in the
past 150 years, signaling the impact of human activity on temperatures
worldwide, researchers said in the journal Science.
Sea levels were rising by about 1 millimeter (0.04 inches) every year
about 200 years ago and as far back as 5,000 years, geologists found from
deep sediment samples from the New Jersey coastline. Since then, levels
have risen by about 2 millimeters (0.08 inches) a year.
While the planet has been in a warmer period, driving cars and other
activities that create carbon dioxide are having a clear impact, the
Rutgers University-led team said.
\"Half of the current rise ... was going on anyway. But that means half of
what\'s going on is not background. It\'s human induced,\" said Kenneth
Miller, a geology professor at the New Jersey-based school who led the
15-year effort.
Carbon dioxide emissions come mainly from burning coal and other fossil
fuels in power plants, factories and automobiles.
Miller and his colleagues analyzed five 500-meter (1,650-foot) deep
samples to look for fossils, sediment types and variations in chemical
composition, giving them data on the past 100 million years.
They also analyzed data from satellite, shoreline markers and by gauging
ocean tides, among other measures.
\"It allows us to understand the mechanisms of sea level change before
humans intervened,\" Miller said in an interview.
His team did not determine whether the rate is accelerating.
The research, funded mostly by the
National Science Foundation, also found ocean levels were lower during the
dinosaur era than previously thought. They were about 100 meters (330
feet) higher than now, not 250 meters (820 feet) as many geologists had
thought, Miller said.
SAMPLES FROM ANTARCTIC DEPTHS
Measurements also showed that, while many scientists had thought polar ice
caps did not exist before 15 million years ago, frozen water at the poles
did form periodically.
\"We believe the ice sheet was not around all the time. It was only around
during cool snaps of the climate,\" Miller said.
In another report published in Science, European researchers using three
large samples of polar cap ice found carbon dioxide levels were stable
until 200 years ago.
\"Today\'s rise is about 200 times faster than any rise recorded\" in the
samples, study author Thomas Stocker said in an e-mail interview with
Reuters.
The historic data \"put the present rise of the last 200 years into a
longer-term context,\" he added.
Trapped gas bubbles in the ice, drilled out from Antarctica depths of
about 3,000 meters (9,900 feet), provided scientists with information on
the Earth\'s air up to 650,000 years ago.
Researchers participating in The European Project for Ice Coring in
Antarctica measured levels of carbon dioxide as well as methane and
nitrous oxide -- two other gases known to affect the atmosphere\'s
protective ozone layer.
\"The study does not directly address global warming. But what we provide
is an important new baseline for the climate models with which we
investigate global warming,\" said Stocker, a professor of climate and
environmental physics at the University of Bern in Switzerland.
[foto] View of Manshuk Mametova glacier melting down to a lake in northern
Tien Shan mountains in Kazakhstan August 24, 2003. Ocean and so-called
greenhouse gas levels are rising faster than they have for thousands of
years, according to two reports published on Thursday that are likely to
fuel debate on global warming. (Alexei Kalmykov/Reuters)
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