“Sound Science,” Common Sense & Global Warming


For anyone who still needs “sound science” about global warming,
here’s a small sampler: Temperatures are rising. James Hansen
and colleagues of New York City’s Goddard Institute observed
that during 2001, global temperatures averaged the second highest
in recorded history (after roughly 1865), exceeded only by the El
Nino year of 1998. “The global warmth of 2001 is particularly
meaningful because it occurs at a phase of the Southern Oscillation
in which the tropical Pacific Ocean is cool,” Hansen and colleagues
wrote in a letter to Science.
The first three months of 2002 were the warmest on the instrumental
record, as a new El Nino took shape in the Pacific Ocean off the
western coast of South America.


“Human activity has raised Earth’s surface temperature
during the last 130 years,” according to a study published
during January 2001 by the Journal of Geophysical Research. Robert
Kaufmann of Boston University’s Center for Energy and Environmental
Studies and David Stern of the Australian National University’s
Centre for Resource and Environmental Study analyzed historical
data between 1865 and 1990.


Using the statistical technique of cointegration, the scientists
compared several factors (including greenhouse-gas levels, human
sulfur emissions, and variations in solar activity) with global
surface temperature in both the northern and southern hemispheres.
Cointegration techniques are not confused by variables that tend
to increase or decrease over time or contain some poor measurements.
This was the first study to make a statistically meaningful link
between human activity and temperature, independent of climate models,
Kaufmann said.


“The countervailing effects of greenhouse gases and sulfur
emissions undercut comments by climate change skeptics, who argue
that the rapid increase in atmospheric concentrations of greenhouse
gases between the end of World War II and the early 1970s had little
effect on temperature,” said Kaufmann. During this period,
Kaufmann said, “the warming effect of greenhouse gases was
hidden by a simultaneous increase in sulfur emissions. But, since
then, sulfur emissions have slowed, due to laws aimed at reducing
acid rain, and this has allowed the warming effects of greenhouse
gases to become more apparent.”


Warming has been most rapid in the polar regions. At Sachs Harbour
on Banks Island in the high Arctic, mosquitoes and beetles are now
common sights where they were unknown a generation ago. Sea-ice
is thinner and now drifts far away during the summer, taking with
it the seals and polar bears upon which the village’s Inuit
residents rely for food.

In
the winter, sea-ice often is thin and broken, making travel dangerous
for the most experienced hunters. In the fall, storms have become
more frequent and more violent, making boating difficult. Thunder
and lightning have been seen for the first time, arriving with another
type of weather that is new to the area, dousing summer rainstorms. “We
have no other sources of food, the people in my community are completely
dependent on hunting, trapping, and fishing,” said Rosemarie
Kuptana, a resident of Banks Island’s only town, Sachs Harbour.
“We have no means of adapting to a different environmental
reality, and that is why our situation is so critical.”

“When
I was a child, I never heard thunder or saw lightning, but in the
last few years we’ve had thunder and lightning,” said
Kuptana. “The animals really don’t know what to do because
they’ve never experienced this kind of phenomenon.  We
don’t know when to travel on the ice and our food sources are
getting further and further away,” said Kuptana. “Our
way of life is being permanently altered.”


Until February 2001, snow was in short supply across much of Alaska.
For several weeks, unusual rain soaked Anchorage region. The snowless
tundra along Norton Sound, near the end of the 1,760-kilometer Iditarod
race trail, was so bare in December that it caught fire. Sufficient
snow to hold the race had fallen by March, however, when the race
is held. During training for the race in the Matanuska-Susitna Valley
40 miles north of Anchorage, much of the ground was bare. The trails
were so icy that dogs risked injury.


In Antarctica, several large ice sheets have crumbled into the ocean
during the last few years. Glaciologists Eric Rignot and Stanley
S. Jacobs have been studying the physical mechanisms behind accelerating
melting of Antarctic ice. They reported in Science, June
14, 2002, that “As continental ice from Antarctica reaches
the grounding line and begins to float, its underside melts into
the ocean. Results obtained from satellite radar interferometry
reveal that bottom melt rates experienced by large outlet glaciers
near their grounding lines are far higher than generally assumed.”


Furthermore, Rignot and Jacobs wrote, “The melting rate is
positively correlated with thermal forcing, increasing by 1 meter
per year for each 0.1 degree C. rise in ocean temperature. Where
deep water has direct access to grounding lines, glaciers and ice
shelves are vulnerable to ongoing increases in ocean temperature.”
If Antarctica is melting around the edges (the same pattern has
been reported in Greenland), why are interior Antarctic temperatures
dropping? Such reports have become grist for anti-warming skeptics
in recent months. One of the scientists who brought these reports
to light has expressed a sense of irritated concern that many of
the media have blown his findings out of proportion vis-à-vis
the general debate on global warming.

Slawek
Tulaczyk of the University of California at Santa Cruz told Keay
Davidson of the San Francisco Chronicle (February 4, 2002)
that press reports had left him “increasingly frustrated”
by sometimes-careless media coverage of the global warming issue.
Tulaczyk and Ian Joughin of the Jet Propulsion Laboratory in Pasadena
reported in the January 18, 2002 issue of Science that the
movement of the glacial Ross ice streams appears to be slowing,
allowing the ice to thicken.

In
another recent study, 13 scientists reported in the January 13,
2002 issue of Nature that while other continents have warmed
to record-high temperatures in recent years, most of the Antarctic
surface has cooled since 1966. Some editorial writers assumed that
if Antarctica is getting cooler, then maybe the whole planet is
cooling, too. “Is Another Ice-Age On the Way?” asked an
editorial in the Rocky Mountain News.


A headline over an editorial in the San Diego Union-Tribune
minced no words about it: “Scientific findings run counter
to theory of global warming.” The editorial sarcastically asked:
“Oh dear. What will the doomsayers say now? How will they explain
away yet two more scientific studies that clearly contradict the
global warming orthodoxy?” A headline in the National Post,
a Canadian newspaper, declared: “Antarctic ice sheet has stopped
melting, study finds.”


“Some media mistakenly equated the phenomenon studied by Joughin
and Tulaczyk—a change in ice flow rates—with ice melting
rates. The mistake contributed to the erroneous belief that the
studies constituted, as it were, scientific ‘tests’ of
the global warming theory,” wrote Davidson.

Contrary
to some news reports, “the ice-sheet growth that we have documented
in our study area has absolutely nothing to do with any recent climate
trends,” Tulaczyk said. “I keep repeating to journalists
that climate science is much like economics. Both deal with complex
systems,” Tulaczyk observed. “Just as a single stock going
up or down cannot be interpreted as a reliable indicator of economic
recovery or collapse, we have to accept the occurrence of contradictory
trends in the global climate.”


Contrary to these and other newspaper reports and opinions, “Global
warming is real and happening right now,”  Peter T. Doran
of the University of Illinois at Chicago, lead author of the Nature
paper told Davidson. Doran said the cooling trend in Antarctica
appears to be a surprising, regional exception to the overall planetary
warming.


Doran emphasized that his team’s report in Nature does
not change the nature of global warming in any significant way.
Roughly half the Antarctic continent is still warming, even given
the new reports, as is most of the rest of the planet. For example,
the Antarctic Peninsula’s Larsen Ice Shelf has warmed 2.5 degrees
Celsius during the last half century, as it disintegrates into the
ocean. The Antarctica Peninsula (stretching northward toward South
America) has been warming very rapidly, about 5 degrees over the
past 50 years, 10 times the global average, matching temperature
rises in Alaska.


The Antarctic cooling may stem from changes in wind patterns. An
explanation of this apparent paradox may lie in a climactic “master
switch” over the high southern latitudes, a circular wind pattern
(the “Antarctic Oscillation”) that is being driven faster
by the depletion of stratospheric ozone.


Writing in the May 3, 2002 issue of Science, David W. J.
Thompson, a professor of atmospheric science at Colorado State University,
and Dr. Susan Solomon, a senior scientist at the National Oceanic
and Atmospheric Administration in Boulder, Colorado, assert that
ozone depletion over the Antarctic may help explain both contradictory
trends. “Ozone seems to be capable of tickling the Southern
Hemisphere patterns,” Thompson said.


Thompson and Solomon link cooling in the stratosphere induced by
depletion of ozone levels to acceleration of the winds. “During
the summer-fall season,” Thompson and Solomon have written,
“The trend toward stronger circumpolar flow has contributed
substantially to the observed warming over the Antarctic Peninsula
and Patagonia and to the cooling over eastern Antarctica and the
Antarctic plateau.”


Thompson and Solomon show that a vortex of winds blowing around
Antarctica that traps cold air at the South Pole have strengthened
in the past few decades, keeping the cold air even more confined.
The Antarctic peninsula lies outside the wind vortex and thus escapes
the cooling effect. Ozone depletion may be a key causal factor in
strengthening the wind pattern, according to Thompson and Solomon.
“That’s where we speculate,” Dr. Thompson said, “and
the emphasis is on the word ‘may’.”


Maryland’s population of Baltimore orioles, long in decline,
could vanish altogether late this century because of dramatic changes
in migration patterns and declining habitats strongly influenced
by global warming. A study by the National Wildlife Federation and
the American Bird Conservancy suggests that global warming  effects
may be driving state birds from Maryland and a half-dozen other
states.


According to the report, rising temperatures are changing migration
patterns and threatening some well-known birds’ ability to
survive. Iowa and Washington state would eventually see their last
American goldfinch, as New Hampshire would fall outside the range
of the purple finch. California quail would skip that state and
Massachusetts’ black-capped chickadee would vanish. Georgia
would lose the brown thrasher and Maryland would fall outside the
range of the Baltimore oriole, according to the study.”


Rising water temperatures caused by global warming also could drive
several cold-water species of trout and salmon from many U.S. waterways,
by the end of the century. In many areas, these fish already are
living at the margin of their temperature tolerance. Defenders of
Wildlife and the Natural Resources Defense Council assert that by
the end of the century, many salmon and trout will be restricted
to the northernmost sections of the United States. The groups’
analysis covers four species of trout—brook, cutthroat, rainbow,
and brow—and four species of salmon—pink, coho, chinook,
and chum. Researchers looked at air and water temperature data from
more than 2,000 sites across the U.S.


“Wild trout and salmon populations are already stressed by
factors such as loss of habitat to development, competition with
hatchery fish, invasive exotic species, and more. Now we must add
climate change to the list of challenges they face,” said Mark
Shaffer, senior vice president at Defenders of Wildlife. “If
we don’t address the cumulative impact of all these factors,
we will see more of these populations switching from a recreational
resource to being listed as threatened or endangered.”



Bruce
E. Johansen, a professor of Communication at the University of Nebraska
at Omaha, is the author of
The Global Warming Desk Reference
(Greenwood Press, 2001).