Yesterday’s News
Two stories in the Alaska section of Sunday’s Anchorage Daily News
caught Greyfox’s eye. He told me about them on the phone and I
went to adn.com
to read them. I thought they’d be worth sharing, especially the first one, since
someone recently asked me if Alaska was getting tropical. Was it pip? I think it was.
Global warming has had little noticeable impact in Washington, D.C.
Politicians in the nation’s capital have been reluctant to set limits
on the carbon dioxide pollution that is expected to warm the planet by
4 to 7 degrees Fahrenheit during the next century, citing uncertainty
about the severity of the threat.
But that uncertainty may have shrunk somewhat with the release last
week of two scientific reports suggesting that global warming is not
just a hypothetical possibility but a real phenomenon that has already
started transforming especially sensitive parts of the globe, including
Alaska.
Overall, the reports say, Earth’s climate has warmed by about 1 degree
Fahrenheit since 1900. In the Arctic, where a number of processes
amplify the warming effects of carbon dioxide, most regions have
experienced a temperature rise of 4 to 7 degrees in the last 50 years.
That warmth has reduced the amount of snow that falls every winter,
melted away mountain glaciers and shrunk the Arctic Ocean’s summer sea
ice cover to its smallest extent in millennia, according to satellite
measurements. Swaths of Alaska permafrost are thawing into soggy bogs,
and trees are moving northward at the expense of the tundra that rings
the Arctic Ocean.
These changes seriously threaten animals such as polar bears, which
live and hunt on the sea ice. The bears have already suffered a 15
percent decrease in their number of offspring and a similar decline in
weight in the past 25 years. If the Arctic sea ice disappears
altogether during summers, as some researchers expect it will by the
end of the century, polar bears have little chance of survival.
Things are less serious in the Lower 48, where effects of climate
change are more subtle. In much of it, spring arrives about two weeks
earlier than it did 50 years ago. Tropical bird species have appeared
in Florida and along the Gulf Coast. Species such as Edith’s
checkerspot, a butterfly native to western North America, have started
dying out at the southern reaches of their ranges.
“Responses to climate change are being seen across the U.S.A.,” said
Camille Parmesan, a biologist at the University of Texas in Austin. She
is the co-author, with Hector Galbraith of the University of Colorado
in Boulder, of “Observed Impacts of Global Climate Change in the U.S.”
The report was released Tuesday by the Pew Center on Global Climate
Change, a nonpartisan but not disinterested research organization
dedicated to providing sound scientific information about global
warming.
Parmesan and Galbraith acknowledge that nothing in the report would
strike the average person as particularly alarming. They also allow
that some of the past century’s warming might have happened even if
humans hadn’t been pumping carbon dioxide into the atmosphere. But they
argue that the changes they describe should be taken as a “very clear
signal” that climate change will have significant effects in coming
decades.
“The canaries in the coal mine are squawking, and we should absolutely take that seriously,” Galbraith said.
The Bush administration has argued that not enough is known about
climate change to justify major efforts at forestalling or preventing
future warming.
The Arctic report, released Monday, was commissioned by the Arctic
Council, an international commission of eight countries, including the
United States, and six indigenous groups. It was written by a team of
300 scientists.
“The report will be a valuable contribution to the literature on
potential regional impacts of climate change, and the United States
government will take its findings into account as it continues to
review the science,” State Department spokesman Richard Boucher said in
a statement released Tuesday.
The United States faces a potential showdown with other members of the
Arctic Council on Nov. 24, when representatives of the organization’s
members are scheduled to meet in Iceland to consider climate change
policy recommendations.
The atmospheric concentration of carbon dioxide has risen from 280
parts per million in 1800 to 380 parts per million today due to the
combustion of fossil fuels. Carbon dioxide causes warming because it
heats up more when exposed to sunlight compared to other atmospheric
gases.
Scientists have always expected the Arctic to respond earlier and more
intensely than other regions to the buildup of carbon dioxide in the
atmosphere, thanks to several phenomena that make the far north
especially sensitive to climate perturbations. When warmer temperatures
melt snow, for example, the bare ground that is exposed absorbs more
heat than the white surface did, causing yet more warming. A similar
thing happens when sea ice melts, exposing open water.
In the past three Septembers the Arctic sea ice has melted back 12 percent to 15 percent beyond its normal minimum extent.
“It almost suggests that maybe we’re about to reach a threshold beyond
which the sea ice may not be able to recover,” said Mark Serreze of the
National Snow and Ice Data Center in Boulder, Colo.
Ice in the interior of the Arctic pack normally remains frozen from
year to year, growing thicker with each season. But the recent increase
in melting has eaten into much of that multiyear ice. So while the
Arctic Ocean still freezes over each winter, more of the solid cover
now consists of thin single-year ice that melts every spring.
The Arctic is also particularly sensitive to warming because its plants
and soil hold less water than those in more temperate environments.
That means more energy reaching the ground is dedicated to heating the
surface instead of evaporating water.
The atmosphere is thinner in the Arctic than it is farther south, which
also intensifies warming. And while temperate zones shed some of their
extra heat by shipping it north in ocean currents and meteorological
fronts, the Arctic is the end of the line in that respect.
A minority of scientists remains unconvinced that increasing
atmospheric carbon dioxide can be held responsible for the recent
warming, arguing that natural variability explains most if not all of
the trend.
“It’s very complicated and I believe people who claim they understand
… are just overestimating drastically their ability to do science,”
said Petr Chylek of the Los Alamos National Laboratory.
Scientists aren’t the only ones who have noticed the Arctic warming
trend. Inuit hunters in Canada and Saami reindeer herders in Finland
have detected shifts in the migratory behavior of animals. In some
cases, people whose elders taught them decades ago how to forecast
storms from wind patterns and cloud formations have lost their
predictive abilities to new weather patterns.
“One of the unique things about Arctic communities is how much they’re
tied to the land, and that’s why this is such a big deal for them,”
said Harvard University geographer Shari Fox Gearheard.
Farther south, where the changes have been much less extreme, a warmer
world remains a hypothetical realm of scientists and environmentalists.
But the latest reports suggest that in some of the world’s more
populated places, astute observers may soon begin to notice that the
climate is changing.
http://www.adn.com/alaska/story/5779406p-5712843c.html
Anyone who hangs around here much knows I’m interested in
paleontology. I’ve been watching the dates for certain
prehistoric events being pushed farther and farther back in time as new
discoveries have been made. Here’s another one:
Asia across Alaska and into the heart of North America thousands of
years earlier than previously thought, a finding that could shake up
the debate over when and how people colonized the Americas.
A fossil jaw snatched from a conveyor belt in a gravel pit near
Edmonton, Alberta, came from a grizzly that died 26,000 years ago. This
suggests the big bears must have migrated south before glaciers blocked
the middle of the continent during the height of the last ice age,
according to a paper published Friday in the journal Science.
Further, a DNA test of the root in the jaw’s second molar showed a
close genetic relationship between that ancient bear and brown bears
now living in the Lower 48 states and southern Canada. And it showed a
far more distant connection to brown bears of the north.
“It’s like finding a missing piece of a puzzle, or even a proverbial
missing link,” said Paul Matheus, lead author of the paper and a
paleobiologist with the Alaska Quaternary Center at the University of
Alaska Fairbanks.
The discovery contradicts a long-standing theory that brown bears, as
well as people, could not walk south from Alaska until glaciers pulled
back and created an ice-free corridor about 13,000 years ago, Matheus
said.
Recent discoveries that people were already living in the Lower 48 and
South America about that time or earlier had spurred a competing
theory. If the ice blocked overland travel, the first Americans must
have traveled along the coast in boats.
But if bears could amble south across the continent before ice sheets climaxed, why not people too?
Over the past decade, geologists have realized that continental ice
sheets didn’t choke off the route from Beringia to lower North America
until about 20,000 years ago, said Matheus, in a telephone interview
last week from his office in Whitehorse, Yukon. Over thousands of
years, that path may have opened and closed many times before the ice
finally receded for good.
“It’s a complex story, and there doesn’t seem to be as much ice as we once thought,” Matheus said.
The new understanding raised a difficult issue for paleontologists: “If
we accept all that, why haven’t these animals gotten down south before?”
Now scientists may need to rethink what was possible for brown bears and prehistoric people, Matheus said.
The discovery builds on earlier work by Matheus into how brown bears
evolved over the past 60,000 years in Beringia, the 1,000-mile-wide
steppe that connected Alaska with Asia. The “land bridge” emerged when
vast continental glaciers locked up water and lowered sea level.
In a paper published by Science in 2002, Matheus and other authors at
the University of Oxford and the Max Planck Institute in Germany
described how eight genetically distinct populations of brown bears
appeared and disappeared over thousands of years, and how they all
related to modern bears in Europe, Asia and North America.
Asian brown bears first colonized North America by spreading into
Beringia between 100,000 and 50,000 years ago. But the animals
disappeared about 35,000 years ago, possibly due to environmental
change or competition with the larger, more ferocious (and now extinct)
short-faced bear, Matheus said.
Bears that returned to Alaska and northwestern Canada about 21,000
years ago are similar to the bears living here now. But these newer
bruins seemed unrelated to brown bears now found in southern Alberta,
British Columbia, Idaho and Montana.
So: Where did modern brown bears in the middle of the continent come
from if their genetic ancestors went extinct in North America 35,000
years ago?
The Alberta fossil offers the answer.
“The mystery has been more or less solved — they walked through
Alberta,” said paleontologist Jim Burns, a co-author of the paper and
curator of ice-age fossils at the Provincial Museum of Alberta in
Edmonton. “This is the first evidence that shows they made the journey
prior to the maximum glaciation when the passage was blocked.”
The bear jaw had been collected in 1997 by Burns along with many other
fossils unearthed in a gravel deposit that dated before the ice age.
“He literally has graduate students standing there at the end of a conveyor, grabbing fossils as they come down,” Matheus said.
During a visit to the museum a few years ago, Matheus identified the
specimen as a brown bear. Radiocarbon tests dated the fossil, and a DNA
analysis proved its connection to modern brown bears of the south.
“It was a serendipitous discovery … and an elegant use of ancient DNA to answer a very specific question,” Matheus said.
http://www.adn.com/alaska/story/5779408p-5712765c.html
When I’m done here, I’ll be suiting up to go out and scrape the ice
from my car windows and warm up the car for our trip to town.
Doug and I will pick up Seph
in Willow, then drive to Yukon’s on the edge of Wasilla, where Greyfox
will meet us for lunch. Seph offered to treat us to lunch, and
gave me the option of where to eat. I chose Yukon’s because of
the complete short-order menu that assures the guys of getting
something they like, the self-service taco bar where I can eat well and
stay on my diet, and the soup, which Greyfox says is always excellent.
I’ll be back.
Doug
not bloody likely, but...] Y’never know who’s watching.
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