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- A worldwide wave of extreme weather inflicted
at least $90 billion in damage in 1998, more than in the entire 1980s.
Last year was also the hottest on record. While no single weather event
or year proves humans are warming the planet, a powerful scientific case
is building. Some of the most compelling evidence emerged in just the past
year.
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- Greenhouse gases are present in the atmosphere
in greater amounts than at any time in at least 220,000 years. Certainly
something is heating the globe. The century's ten warmest years have all
occurred since 1983--seven in this decade. A new National Science Foundation
study based on natural indicators such as tree rings, ice-cores, and corals
finds the last decade of the millennium has been its hottest. And 1998
was by far the hottest year. Temperatures surged faster than previously
documented to break a record set in just the previous year, 1997.
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- Middle and lower latitude mountain glaciers
are showing the effects. University of Colorado glaciologists at Boulder
in 1998 reported that those glaciers have retreated on average at least
60 feet since 1961, and the rate at which they are melting is increasing.
The retreat of mountain ice in tropical and subtropical latitudes provides
"some of the most compelling evidence yet for recent global warming,"
Ohio State University researchers note.
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- A new study by NASA's Goddard Institute
found Greenland glaciers appear to be spewing icebergs into the ocean faster
than in the past. The finding was unexpected, and raises fears that global
sea levels, already projected to rise 20 inches next century, could increase
even faster.
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- Predictions that global warming will
be greatest in the polar regions are now being borne out. Arctic sea ice
has been shrinking by 3 percent each decade since 1970. Several of the
years with the smallest sea ice coverage were in the 1990s. Around the
Antarctic Peninsula, extensive sea ice formed 4 winters out of every 5
in the mid-century. Since the 1970s that dropped to 1-2 winters out of
every 5.
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- Several Peninsula ice shelves, which
attach to the continent but stretch into the sea, are in retreat. Some
of the most dramatic losses came in 1998, when around 2,000 square miles
calved into icebergs. The Larsen A ice shelf, after years of slowly melting
away, suddenly disintegrated in 1995. Scientists have now mounted a death
watch for Larsen B and Wilkens--together three times larger than Delaware.
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- Since ice shelves already displace water,
the loss will not add to rising ocean levels. But melting northern tundra
could have a devastating global effect. Carbon in tundra soils, equal to
one-third that in the atmosphere, could be released. Tundra researcher
George W. Kling of the University of Michigan says, "Our latest data
show that the Arctic is no longer a strong sink for carbon. In some years,
the tundra is adding as much or more carbon to the atmosphere than it removes."
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- A warmer atmosphere is expected to cause
more evaporation, making for worse droughts and more deluges. Beginning
around 1980, sections of the U.S., Europe, Africa, and Asia began to experience
more dry spells, while parts of the U.S. and Europe became much wetter.
The National Climatic Data Center scrutinized U.S. weather records for
extremes expected to increase under global warming. NCDC discovered that
wild weather has been surging since the late 1970s. Statistical analysis
showed only 1-in-20 odds that this was a natural fluctuation. NCDC Chief
Scientist Tom Karl commented, "I would say the climate is responding
to greenhouse gases."
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- Thick, precipitation-prone clouds significantly
increased over Australia, Europe, and the United States between 1951 and
1981. Researchers concluded the increase is "likely to be related"
to human-caused greenhouse gases.
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- Cloud cover holds in heat after the sun
goes down. So nighttime warming is a significant global warming indicator.
Nighttime temperatures are going up more than twice as fast as daytime
temperatures. Extreme summer heatwaves in the U.S increased 88 percent
between 1949-95, with the biggest heat increases coming at night.
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- Warming is having devastating impacts
on plant and animal life. Coral reefs, the "rainforests of the ocean,"
where one-quarter of all marine species are found, suffered record die-off
due to heat-induced bleaching in 1998. "At this time, it appears that
only ... global warming could have induced such extensive bleaching simultaneously
throughout the disparate reef regions of the world," a State Department
scientific report concluded.
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- A dramatic temperature increase off North
America's west coast began around 1977. Zooplankton, the microscopic plant-eaters
that form the base of the marine food chain, dropped 70% because warmer
waters suppressed colder, nutrient-rich currents. Indicating food chain
collapse, ocean seabirds in the California Current have declined 90% since
1987.
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- As the Pacific has warmed, so has Alaska.
On the south central coast, cool temperatures normally keep the spruce
bark beetle under control. But with the warming, beetles have killed most
of the trees in a space of three million acres, one of the largest insect-caused
forest deaths in North American history.
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- Evidence is mounting that global warming
is here and humanity is driving it. Remaining scientific uncertainty "does
not justify inaction in the mitigation of human-induced climate change
and/or the adaptation to it," the American Geophysical Union said
in a recent statement. The emerging scientific consensus leaves us with
no excuses. We must rapidly transition from fossil fuels to clean energy.
The global climate crisis, perhaps the greatest challenge in the history
of civilization, calls upon us to act decisively and without delay.
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- --Patrick Mazza and Rhys Roth
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- This article is excerpted from a new
white paper, Global Warming Is Here: The Scientific Evidence, available
from Climate Solutions, 610 E. 4th St., Olympia, WA 98501, USA, phone (360)
352-1763, info@climatesolutions.org
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