THE FOX WHO GOT READY FOR AN ICE AGE

FROM:  NATIONAL SCIENCE FOUNDATION 

"Out of Tibet" hypothesis: Cradle of evolution for cold-adapted mammals is in Tibet

Extinct Tibetan fox, ancestor of today's arctic fox, used Tibet as training ground for Ice Age climate

June 11, 2014

For the last 2.5 million years, Earth has experienced millennial-long cold and warm cycles. During cold periods, continental-scale ice sheets have blanketed large tracts of the Northern Hemisphere.

As climate warmed, glaciers receded, leaving Yosemite-like valleys and similar geologic features behind.

The advance and retreat of the ice sheets also had a profound influence on the evolution and geographic distribution of many animals, including those that live in far northern regions.

New results from research conducted in the Himalayan Mountains and published this week in the journal Proceedings of the Royal Society B: Biological Sciences identify a recently discovered three to five million-year-old Tibetan fox, Vulpes qiuzhudingi, as the likely ancestor of the living arctic fox, Vulpes lagopus.

The finding lends support to the idea that the evolution of present-day animals in the Arctic traces back to ancestors that adapted to life in cold regions in the high-altitude Tibetan Plateau.

The paper's lead author is Xiaoming Wang of the Natural History Museum of Los Angeles County. Co-authors are Zhijie Jack Tseng from the University of Southern California, Qiang Li from the Chinese Academy of Sciences, Gary Takeuchi from the Page Museum at the La Brea Tar Pits and Guangpu Xie from the Gansu Provincial Museum.

The scientists, part of a team of geologists and paleontologists led by Wang, uncovered fossil specimens of the Tibetan fox in the Zanda Basin in southern Tibet.

In addition to the fox, the team also discovered extinct species of a wooly rhino (Coelodonta thibetana), three-toed horse (Hipparion), Tibetan bharal (Pseudois, known as blue sheep), chiru (Pantholops, known as Tibetan antelope), snow leopard (Uncia), badger (Meles), and 23 other mammals.

The new fossil assemblage lends credence to a scenario the scientists call the "Out of Tibet" hypothesis.

It argues that some Ice Age megafauna--which in North America include the woolly mammoth, saber-toothed cat and giant sloth--used ancient Tibet as a training ground for developing adaptations that allowed them to cope with a harsh climate.

"The concept 'Out of Tibet' is an exciting insight for the origin of cold-adapted mammals of the Pleistocene," says Rich Lane, program director in the National Science Foundation's (NSF) Division of Earth Sciences, which funded the research.

"It parallels the 'Out of Africa' theory for the evolution of hominids. Together they may be a model for wider application in biological history and geography."

Tibet, Wang says, is a rich but grueling location for paleontological fieldwork.

Fifteen summer field seasons and a great deal of luck have led to his and his colleagues' successes.

Their expeditions involve a one-week journey to Lhasa, then a four-day drive into the remote "layer cake" sediments of the Zanda Basin--a drive made in old-model Land Cruisers known for becoming mired in streambeds.

At the more than 14,000-foot elevation, it's difficult to breathe, water freezes overnight in camps, and the scientists often must walk alone in search of fossils.

They've trained their eyes to search for ancient lake margins, where megafauna are reliably found.

Despite the challenges, Wang says that it's his favorite place to look for fossils.

"It's a pristine environment, the Tibetan people are kind, and in paleontological terms," he says, "it's relatively unexplored."

-- Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov
-- Kristin Friedrich, L.A. County Museum of Natural History (213) 763-3532 kfriedri@nhm.org
Investigators
Xiaoming Wang

RESEARCH SHOWS EARTH WARMER NOW THAN IN MOST OF LAST 11,000 YEARS

Along Greenland's western coast, a small field of glaciers empties into Baffin Bay, 80% of which is covered by ice in winter. Calving icebergs may be seen in the lower right of this high-resolution satellite photo. Baffin Bay is only 1,000 m (3,300 ft) deep along the coast. Between May and July a polynya, an area of navigable open water surrounded by sea ice, forms at the northern part of the bay. This polynya, the largest in the Canadian Arctic, is stable in location and has existed for nearly 9,000 years. Image courtesy of USGS.

 
FROM: NATIONAL SCIENCE FOUNDATION
Earth Is Warmer Today Than During 70 to 80 Percent of the Past 11,300 Years

With data from 73 ice and sediment core monitoring sites around the world, scientists have reconstructed Earth's temperature history back to the end of the last Ice Age.

The analysis reveals that the planet today is warmer than it's been during 70 to 80 percent of the last 11,300 years.

Results of the study, by researchers at Oregon State University (OSU) and Harvard University, are published this week in a paper in the journal Science.

Lead paper author Shaun Marcott of OSU says that previous research on past global temperature change has largely focused on the last 2,000 years.

Extending the reconstruction of global temperatures back to the end of the last Ice Age puts today's climate into a larger context.

"We already knew that on a global scale, Earth is warmer today than it was over much of the past 2,000 years," Marcott says. "Now we know that it is warmer than most of the past 11,300 years."

"The last century stands out as the anomaly in this record of global temperature since the end of the last ice age," says Candace Major, program director in the National Science Foundation's (NSF) Division of Ocean Sciences. The research was funded by the Paleoclimate Program in NSF’s Division of Atmospheric and Geospace Sciences.

"This research shows that we've experienced almost the same range of temperature change since the beginning of the industrial revolution," says Major, "as over the previous 11,000 years of Earth history--but this change happened a lot more quickly."

Of concern are projections of global temperature for the year 2100, when climate models evaluated by the Intergovernmental Panel on Climate Change show that temperatures will exceed the warmest temperatures during the 11,300-year period known as the Holocene under all plausible greenhouse gas emission scenarios.

Peter Clark, an OSU paleoclimatologist and co-author of the Science paper, says that many previous temperature reconstructions were regional and not placed in a global context.

"When you just look at one part of the world, temperature history can be affected by regional climate processes like El Niño or monsoon variations," says Clark.

"But when you combine data from sites around the world, you can average out those regional anomalies and get a clear sense of the Earth's global temperature history."

What that history shows, the researchers say, is that during the last 5,000 years, the Earth on average cooled about 1.3 degrees Fahrenheit--until the last 100 years, when it warmed about 1.3 degrees F.

The largest changes were in the Northern Hemisphere, where there are more land masses and larger human populations than in the Southern Hemisphere.

Climate models project that global temperature will rise another 2.0 to 11.5 degrees F by the end of this century, largely dependent on the magnitude of carbon emissions.

"What is most troubling," Clark says, "is that this warming will be significantly greater than at any time during the past 11,300 years."

Marcott says that one of the natural factors affecting global temperatures during the last 11,300 years is a gradual change in the distribution of solar insolation linked with Earth's position relative to the sun.

"During the warmest period of the Holocene, the Earth was positioned such that Northern Hemisphere summers warmed more," Marcott says.

"As the Earth's orientation changed, Northern Hemisphere summers became cooler, and we should now be near the bottom of this long-term cooling trend--but obviously, we're not."

The research team, which included Jeremy Shakun of Harvard and Alan Mix of OSU, primarily used fossils from ocean sediment cores and terrestrial archives to reconstruct the temperature history.

The chemical and physical characteristics of the fossils--including the species as well as their chemical composition and isotopic ratios--provide reliable proxy records for past temperatures by calibrating them to modern temperature records.

Analyses of data from the 73 sites allow a global picture of the Earth's history and provide a new context for climate change analysis.

"The Earth's climate is complex and responds to multiple forcings, including carbon dioxide and solar insolation," Marcott says.

"Both changed very slowly over the past 11,000 years. But in the last 100 years, the increase in carbon dioxide through increased emissions from human activities has been significant.

"It's the only variable that can best explain the rapid increase in global temperatures."

-NSF-