November 15, 2004

• 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.

  MELTDOWN
  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:

  Prehistoric brown bears spread from
  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.
  

  • 2:15 pm
  • 7 Comments