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.
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 10 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 just in 1997.
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.
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.
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 5.
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 loss
in one year equaled the average of 10-15. 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.
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."
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 did begin to experience more dry spells,
while parts of the U.S. and Europe have become 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 it was a natural fluctuation.
NCDC Chief Scientist Tom Karl commented, "I would say the climate is
responding to greenhouse gases."
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.
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.
Warming is having devastating impacts on plants and animals. 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
"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.
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 percent because warmer waters
suppressed colder, nutrient-rich currents. Indicating food chain collapse,
ocean seabirds in the California Current have declined 90 percent since
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 the beetles have killed most trees over three million
acres, one of the largest insect-caused forest deaths in North American
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.
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, firstname.lastname@example.org