A Report Produced by The CO2 & Climate Team
Not All That It's Cracked
Up To Be
One article in the scientific journal Geophysical
Research Letters; three different takes on what it all means.
The
largest ice shelf in the Northern Hemisphere has broken in two, draining
a freshwater lake beneath the ice and providing further evidence of
climate change in the Earths Arctic reaches... The
Washington Post.
The
scientists who report the break-up in the journal Geophysical Research
Letters (GRL) say it is further evidence of ongoing and accelerated
climate change in the north polar regions. BBC News.
I am
not comfortable linking it to global warming. It is difficult to tease
out what is due to global warming and what is due to regional warming.
Study coauthor Derek Mueller, in an interview on MSNBC.
This story
has its roots in research by Warwick Vincent and Derek Mueller (scientists
from Laval University in Quebec City, Canada) along with Martin Jeffries
of the University of Alaska- Fairbanks. They monitor the Ward Hunt Ice
Shelf on the north coast of Ellesmere Island on Canadas Arctic coast
using satellite-based radar imagery and helicopter overflights. This particular
ice shelf dams a freshwater lake in the Disraeli Fjord. Or
at least it used to. The dam began its break-up with a crack that developed
in April 2000. Since then, the crack has become so large that the freshwater
lake has drained into the Arctic Ocean.
So what, you ask? The
break up signals a major change in the areas ecosystem and there
is a question if global warming, which is anticipated first to be signaled
by warming of the Arctic climate, is the cause.
If the locale for this change was
the Antarctic, the cute and lovably awkward penguin would be the poster
child for this crisis. But with no penguins in the Arctic, the best the
ecosystems champions can do is to feature a rare alga. According
to Jeffries in the BBC report, These are very rare and unusual ecosystems,
and they have been studied as possible analogues for life on a colder
Earth and life on the planets. And if we are losing them, we are losing
the opportunity to study life earlier in Earth history and elsewhere in
the Solar System.
If Earth is hurtling toward a globally-warmed
future, why would anyone care about analogues for what life is like when
it is colder? The key is in those words about other planets.
A popular motif in science fiction is humankind abandoning Earth for colder
planets because humankind has so polluted our atmosphere, that we have
created a runaway greenhouse effect. In that case, well need to
know about the algae we will encounter, there. Or, if we find such algae
in advance, it perhaps will suggest potential for terra-forming. Or it
might suggest the place could eventually become more earth-like, naturally.
Whatever.
What of the temperature angle, then?
It is assumed the Ward Hunt ice sheet has existed for 3,000 years in fairly
stable condition. Nevertheless, by 1982 ninety percent of the ice shelf
had disappeared. Then, confoundingly, its breakup stabilized over the
course of the next two decades.
Was there anything special about
the pattern of Arctic temperature heading into 1982? No, not much. Figure
1 depicts summer temperatures over the Arctic as published by Serreze
et al in 2000. Not only was 1982 not noteworthy, the warm spell in
the late 1990s was comparable to a similar period in the 1930s. Linking
changes in temperature in the algas ecosystem to the dams
break-up may not be so simple after all.
Much to its credit, MSNBCs
coverage emphasizes the angle of local warming. Local warming of
the climate is to blame...[the authors] did not have the evidence needed
to link the melting ice to the steady, planet-wide climate change known
as global warming, is how the network encapsulated its coverage
of this breaking news.
In their soon-to-be-published Geographical
Research Letters paper, the authors note that, in recent years, July
temperatures on the Ward Hunt Shelf have increased to slightly above freezing.
The resulting puddles change solar radiation absorption on the surface,
thereby accelerating the melting rate, according to National Center for
Atmospheric Researchs Kevin Trenberth as quoted in staff writer
Guy Gugliottas article for The Washington Post.
According to Gugliottas reporting
far down his inverted pyramid, even Trenberth (who is renowned for his
apocalyptic perspective on the prospect of global warming) notes how these
High Arctic events probably have little to do with greenhouse gas increases.
Other explanations for the break-up
abound. It may be due to differing freeze-thaw cycles or changes in winds
and tides. It may be due to differences in temperature, salinity, and
circulation patterns in the Arctic Ocean. Who knows?
Although reporting the studys
co-author reluctance to attribute the ice shelf cracking to global warming,
the Posts headline writers opine Ice Shelf Break in
Arctic Attributed to Climate Warming. Come to think of it, thats
actually pretty clever headline writing. Its not global warming
thats to blame, it is climate warming (which could, in fact,
be local). How many of the Posts readers do you think picked
up on that subtle distinction?
This
leads us to a simple, admittedly rhetorical, question: Whenever someone
(whether they be an average reader, media watchdog, or scientist) accuses
the Post of biased reporting on climate change research, why does
it even bother to deny the charge?
Reference:
Serreze, M.C., et al., 2000, Observational Evidence of Recent Change in
the Northern High-Latitude Environment. Climatic Change, 46,
159207.
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Figure 1. Annual
and seasonal Arctic temperature histories published by Serreze et
al. Temperatures in the late 1990s are not much different than those
of the mid-1930s.
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