Archive for the ‘Climate Change’ Category

This true-color image shows southwestern Australia as it appeared on 18 August 2002. A significant chunk of the coastal region is green, a sign that ample seasonal rainfall has done its job. However, to the north and east, hot and dry conditions persist, as a reminder that much of the Australian landscape is dominated by the arid and semi-arid “Outback.”

Australia is the driest inhabited continent, and it is getting drier. The patches of temperate and sub-tropical areas along the coast (including the pictured bit of southwestern Australia) are getting warmer, but receiving less rainfall. Much of southeast Australia (including most of the major urban centers) has been wracked by a decades-long drought. The Murray-Darling river system in the southeast, the only major river system on the continent, is drying up quickly, depriving the country’s limited agricultural land of much-needed irrigation. Cities like Western Australia’s Perth (with a 2009 population of 1,659,000) have seen water demand spike as reservoirs drop. Already, the country has three desalination plants operating to provide water for coastal cities, with three more under construction and at least one more planned. These desalination plants will likely increase Australia’s greenhouse gas emissions, already the highest per capita in the world.

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A new strain of virulent fungus is spreading quickly through the Pacific Northwest. The culprit is actually a type of yeast, Cryptococcus gattii (pronounced “Krypto-cockus gat-ee-eye”). This isn’t your beer or bread yeast. Cryptococcus gattii (C. gattii for short) was already well known in more tropical locales: New Guinea, northern Australia, Brazil, and India. In Australia, C. gattii likes to hang around eucalyptus trees. The spores, when inhaled by an animal (including us) can cause a ferocious and potentially fatal respiratory disease, cryptococcosis. C. gattii can also attack the nervous system, causing meningitis or lesions. However, human cases of C. gattii infection in the tropics remained rare (and the fungus can’t be spread from person to person). All in all, this pathogen remained a medical oddity to be aware of, not a cause for public panic.

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In 2007, a reindeer herder and his two sons found this remarkably well-preserved baby woolly mammoth frozen solid in the Yamal-Nenets Autonomous Okrug (District) in northern Russia. The herder named her (for it is indeed a she) Lyuba, after his wife. The International Mammoth Committee, a consortium of scientists dedicated to the preservation and study of mammoth remains, has safeguarded and studied Lyuba ever since. Usually quartered at the Shemanovsky Yamal-Nenets Museum and Exhibition Centre in Salekhard, Russia, she is beginning a tour across the United States. Her first stop is Chicago’s Field Museum of Natural History.

Scientists report that Lyuba lived a tragically short life. Yet, the unique circumstances of her death have permitted us to learn a great deal about her mammoth kin, who roamed the planet as recently as ten millennia ago. Some 42,000 years ago, when Lyuba was just one month old and still nursing on her mother’s milk, fell into a muddy river bank. Struggling in vain to free herself, she sank and suffocated in the muck. Her remains froze in the permafrost, slowing decay and preserving soft tissue, skin, hair, and even stomach contents.

In short, Lyuba (pronounced Lee-OO-bah) is a rare and Earth-shattering find. As far as mammoth remains go, we’re used to finding skeletons, occasionally clumps of hair or tissue, or one or two mummified remains. A whole frozen animal can (and in this case, has) revealed a lot. CAT and MRI scans of her soft tissues have shown us how her innards are arranged. Stomach contents revealed that she’d still been nursing when she died. Hair and skin samples have even given molecular biologists like me something to drool over: a rare specimen of intact mammoth DNA!

Lyuba’s tour of the United States will hopefully draw attention to the problems faced by the International Mammoth Committee. Most woolly mammoth specimens (skeletal or otherwise) that have been recovered frozen and relatively well-preserved in permafrost. However, as Siberian permafrost melts for good, no one knows how many undiscovered mammoth specimens there are that will begin to thaw and decay. The International Mammoth Committee is racing against time to unearth mammoth remains and preserve them for study. Otherwise, we’ll only have a handful of samples like Lyuba to help us understand these elephant relatives that roamed the northern latitudes with our ancestors.

If you find yourself in Chicago up through 6 September 2010, head on over to the Field Museum and see Lyuba for yourself. The exhibit will also go to Boston, Jersey City, Saint Louis, Denver, San Diego, and Anchorage.

Image of Lyuba, a one-month old female woolly mammoth (Mammuthus primigenius) preserved by Siberian permafrost, is provided courtesy of the International Mammoth Committee and Francis Latreille.

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Last night, I listened to a fascinating (but depressing) program on Wisconsin Public Radio’s To the Best of Our Knowledge. The topic: “Polar Stories.” I especially paid attention to a rather downtrodden segment on the future of the polar bears (or lack thereof) as sea ice over the Arctic Ocean disappears. The verdict: they’ll be gone in my lifetime.

Even if polar bears aren’t your thing, the entire program is worth a listen. They cover polar geology, the sensation of cold at the poles, and even Antarctic fiction.

Public radio isn’t the only venue reporting on the polar regions. This morning, the New York Times jumped into the Arctic arena with an article on the demise of the harp seal.

All this talk of the Arctic thaw made me wish humankind had some sort of Arctic ice tracking service… and, as it turns out, we do! The National Science Foundation and NASA have teamed up to create the National Snow and Ice Data Center. They have maps and datasets tracking Arctic ice, as well as simple explanations for those of us who don’t eat, sleep, and breathe oceanography or climatology. Take a look!

Image: three polar bears investigate an intruder, the Los Angeles Class attack submarine U.S.S. Honolulu (SSN 718), after it surfaced through Arctic sea ice some 280 miles from the North Pole in 2003.
Image credit: Chief Yeoman Alphonso Braggs, United States Navy.

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While I was enjoying the gorgeous views of British Columbia’s Sunshine Coast from the many ferry rides it took to get to Texada Island on Thursday, Andrew Revkin posted new findings concerning climate change and ocean currents on the New York Times blog Dot Earth.

A short summary: ocean currents as they’re currently set up help distribute warmer waters from equatorial regions toward the poles, and bring cold water back to the equatorial regions to be heated. This planet-wide circulation pattern has tremendous effects on local climates. One famous result of these current networks is that northern Europe’s climate is kept much warmer than it would otherwise be based solely on its latitude.

For several years now, scientists have worried that these circulation patterns in the north Atlantic Ocean could be disrupted by climate change. The problem centers on melting ice: rising temperatures may shrink or completely melt the massive ice sheet covering Greenland, discharging huge amounts of cold freshwater into the north Atlantic. As a result, these ocean circulation networks in the north Atlantic could slow down (a bad event) or break down entirely (a topic of the disaster film The Day After Tomorrow). While the sudden collapse of the north Atlantic circulation pattern was a highly unlikely scenario, even the current’s slowdown could cool northern Europe to a climate not seen in recorded history.

However, new research from NASA’s Jet Propulsion Laboratory measuring has added silver lining to the climate change cloud. Sure, parts of the Greenland ice sheet are melting, but so far the speed of the north Atlantic currents has remained stable since the 1990s. Currents keep bringing warm water up from the equatorial regions, and transporting cool water down to be re-heated, despite the increasing discharge of freshwater.

Many questions remain:

  • How fast is the Greenland ice sheet melting, and will it melt entirely?
  • What about the potential loss of sea ice from the Arctic?
  • Could there be other sources of freshwater discharge into the north Atlantic and Arctic, such as increasing stream and river discharges from a warmer Canada or Russia?
  • Will the currents still remain stable in the coming decades?

And of course, even if all these melting events don’t slow ocean circulation patterns significantly, there’s another major problem we still have to deal with: all these melting glaciers and ice sheets are going to raise global sea levels.  It’s not a matter of “if,” but “how much?”

Video of ocean current circulation patterns courtesy of NASA’s Goddard Space Flight Center.

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NPR had a fascinating story this morning on a new comprehensive study launched by the National Academy of Sciences. While the title of this post might make you think that the project is trying to predict how future climate change may influence human evolution, this project is peering instead into humankind’s past.

Did Climate Change Drive Human Evolution?

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