——– Original Message ——–
Subject: [Stumps] PLOS : Fire moving higher
Date: Wed, 5 Mar 2008 08:46:44 -0700
From: Lance Olsen <lancolsn@gmail.com>
To: Climate Change and Biodiversity list <gwspecies@lists.onenw.org>
Over and over again, we see changes at the high latitudes matched by
changes at the high altitudes. For an example from the Northern
Hemisphere, the glacial melting at Greenland is matched by the glacial
melting at Glacier National Park. Likewise, we see concern for the
high latitude polar bear matched by concern for a high altitude
species like the pika.
Well, of course, since high latitude and high altitude share so much,
including temperature levels and species not found at lower
altitude/latitude. And the ptarmigan probably deserves some special
notice, because it is distributed over low elevations at high
latitudes and at high elevations at lower latitudes like Glacier
National Park.
So the research described below for high latitude migration of shrubs
and subsequent fire seems a pretty good indicator of what we might
expect for high mountain elevations at points much farther south. And
this article catches my eye because, in seminars here, I’ve described
conditions (drought) that will set up the high elevations for fire,
and because Swetnam has pointed out that fires in the US Southwest
have already been moving into higher elevations. Fire, it seems, is
and will be moving higher.
Lance Olsen
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Frequent Fires in Ancient Shrub Tundra: Implications of Paleorecords
for Arctic Environmental Change
Philip E. Higuera, Linda B. Brubaker, Patricia M. Anderson, Thomas A.
Brown, Alison T. Kennedy, and Feng Sheng Hu
PLoS ONE. 2008; 3(3): e0001744. Published online 2008 March 5
to see the full article, go to:
http://www.pubmedcentral.nih.gov/tocrender.fcgi?iid=161333
As reported by Bloomberg
March 5, 2008
Arctic Tundra May Burn as Global Warming Increases Shrub Cover
By Alex Morales
March 5 (Bloomberg) — Arctic tundra may burn more frequently as the
warming climate allows flammable vegetation to creep northward, U.S.
scientists said.
An analysis of Arctic sediments from thousands of years ago showed
bigger shrubs were more common — as were fires that destroyed them,
researchers led by Philip Higuera at Seattle’s University of
Washington found. With plant life again increasing, fires could become
more frequent, Higuera said.
“There is evidence of increasing shrub biomass in modern tundra
ecosystems, and we expect temperatures to continue to increase and
overall moisture levels to decrease,” Higuera said in a statement.
“Combine these two factors, and it suggests a greater potential for
fires. The sediment cores indicate that it’s happened before.”
The findings may add another “feedback loop” to forecasts of climate
change, in which warmer temperatures trigger changes that then cause
further heating. More Arctic fires could further fuel global warming
as carbon locked up in tundra soils is released into the atmosphere,
the researchers said.
Greenhouse gases such as carbon dioxide trap the sun’s heat in the
atmosphere, raising temperatures, a phenomenon that United Nations
scientists warned last year could increase sea levels and drought and
alter patterns of disease. The UN panel forecast that global
temperatures will warm by 1.1 to 6.4 degrees Celsius (2 to 12 degrees
Fahrenheit) by 2100.
Fire Frequency
The researchers’ findings are published today in the journal Public
Library of Science One. The scientists analyzed sediment cores from
four Alaskan lakes to determine the frequency of fires both now and in
the past. From 14,000 to 9,000 years ago, a typical patch of tundra
burned about once every 144 years, a rate exceeding present fire
frequency, Higuera said.
“This was a surprise: modern tundra burns so infrequently that we
don’t really have a good idea of how often tundra can burn,” Higuera
said. “Best estimates for the most flammable tundra regions are that
it burns once every 250-plus years.”
While the past historical sediment records of Arctic tundra provides a
useful guide to what may happen in the future, they are still
“imperfect analogs,” the researchers said. The historical record
showed one dominant shrub, called betula. Now three species are
spreading in the tundra: betula, and two less flammable plants, alnus
and salix, the researchers said.
Last Updated: March 5, 2008 07:13 EST
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