Far North Science

Woolly Mammoth
Credit: Wikipedia Commons

Once upon a time, the prehistoric steppes of North America hosted a menagerie of giant mammals — woolly mammoths, saber-toothed tigers, cave bears, camels, horses, lions, giant ground sloths as well as bison, moose, musk-oxen and even spear-chucking humans dressed in fur.

As any video-watching child knows well, the late centuries of the ice age fairly rocked with these immense beasts and their furry companions.

And then, about 13,000 years ago, most of this fabulous megafauna rapidly died out. Mammoths went extinct. Lions and tigers and horses and sloths disappeared. Scientists have long debated the causes.

Was it overhunting by Pleistocene humans with spears, wild fire and shrewd killing strategies? Or was it a sudden shift in the climate that destroyed the productive grassy steppe that supported this network of grazers and their predators?

Now, an international team of scientists led by Richard Firestone of Lawrence Berkeley National Laboratory has uncovered evidence that an immense explosion — accompanied by a nuclear-strength shockwave — triggered a catastrophic climate shift that wiped out life across America. The work follows up on earlier findings by Firestone that a supernova 41,000 years ago may have created a killer space rock and sent it tumbling into the home planet.

In other words, just like the dinosaurs before them, the mammoths may have been fried by an asteroid.

Read on » » » »

Microwave data from the Special Sensor Microwave
Imaging radiometer was used to create this image of
the 2007 Greenland melting anomaly which reflects the
difference between the number of melting days occur-
ring in 2007 and the average number of melting days
during the period 1988 - 2006.
Credit: NASA/Earth Observatory

As if the Arctic Ocean record meltdown wasn’t bad enough, NASA scientists say the Greenland ice pack has been melting faster.

Remember: Loss of the Greenland ice sheet is one of the final, city-swallowing catastrophes of runaway climate warming. Put that ice in the ocean as water, and sea level rises almost 24 feet.

This summer, melt ranged over the entire ice sheet. But with a twist:

“Melting in high-altitude areas was greater than ever at 150 percent more than average,” NASA reported in this online story. “In fact, the amount of snow that has melted this year over Greenland could cover the surface size of the U.S. more than twice.”

The results came from Marco Tedesco, a research scientist at the Joint Center for Earth Systems Technology, cooperatively managed by NASA’s Goddard Space Flight Center in Greenbelt, Md., and the University of Maryland at Baltimore County.

With satellite data, Tedesco comparged average snow melt between 1988 and 2006 with the melt observed during 2007. What he found matches may as alarming as the sudden shinkage of the polar ice cap north of Alaska and Siberia.

“In high altitude areas over 1.2 miles above sea level, the melting index — an indicator of where melting is occurring and for how long — was significantly higher than average,” NASA reported in this online story.

“Melting over those areas occurred 25-30 days longer this year than the observed average in the previous 19 years.”

Read on » » » »

Source: NASA

The recent shrink of the Arctic ice cap has stunned scientists and swamped previous projections. After melting back at a rate never seen before, the 2007 minimum ice extent fell 1 million square miles below the 29-year average for September — the loss of a habitat as large as Argentina.

The decline occurred much faster than scientists thought possible, consuming as much ice in one season as one might expect to lose over three consecutive summers, according to a story published online by NASA.

Here’s the latest from the Arctic slush bowl. And the news is not reassuring.

As of Sept. 25, the ice cover in the Arctic Ocean hovered at about 1.61 million square miles — a scant 1 percent increase over the all-time minimum extent observed about 10 days earlier. The Northwest Passage, more ice free than at any time in decades, had slowly begun to clog up. But open water extended hundred of miles north and west of Alaska, exposing coastal villages to enormous fetches for storms and forcing marine mammals to deal with the smallest and most seaward ice habitat of their lives.

Stranded on the Beaufort Sea shore?
Source: FWS/Susanne Miller

As the Bush Administration spends time chatting with other major carbon-producing nations about making soft, ineffectual (and almost certainly symbolic) reductions in greenhouse gas emissions, the Arctic has gone soggy, appearing as ice-free as some climate researchers once predicted for 2050. (See the UN meeting on clmate change earlier in week.)

In fact, given the accelerated rate of melt, several scientists now say the ocean could become ice free in summer as early as 2030. That’s only 23 years — less than a generation for coastal residents, ice seals and bears.

“The amount of ice loss this year absolutely stunned us,” ice scientist Mark Serreze of the National Snow and Ice Data Center, told the Boulder Daily Camera in this story. “It didn’t just beat all previous records — it completely shattered them.”

“Going, going, gone,” Deborah Williams of Alaska Conservation Solutions, told the House Select Committee on Energy Independence and Global Warming, in a story published in the Anchorage Daily News. “We must take action now; it is urgent. We want to be part of the solution, not just the poster child of the problem.”

Read on » » » »

Remains of bearded seal (Erignathus barbatus) of all ages
have been recovered from the Amaknak Bridge site on
the Island of Unalaska in the eastern Aleutians. Shown
here are mandibles from a fully mature prehistoric
adult and a pup several weeks old (top). Bearded seals
give birth on sea ice in early April and nurse their young
for about three weeks.

Winter ice once clogged the Bering Strait until late summer and surrounded the rugged shores of the Pribilof Islands most of the year, according to a new study of ancient animal bones at an Aleutian archeaological site.

This frigid climate, occurring during a mysterious 2,000-year-long cold snap that ended about 2,500 years ago, was powerful enough to trigger decisive shifts in the migrations of whales and the breeding habits of Northern fur seals, ultimately creating a thriving ecology very different than the one observed during the past few hundred yeaers.

Two Canadian archaeozoologists — Susan Crockford and Gay Frederick of Pacific Identifications Inc — say the findings suggest a startling conclusion: that marine mammals like seals may be far more adaptable that people realize.

“Sea ice not only extended further south than it does today but persisted longer into the summer,” they added. “No other type of evidence has documented an expansion of sea ice in the Bering Sea during this time period, which appears to explain the prehistoric distribution of at least one North Pacific marine mammal.”

Among other things, the two scientists found remains of a newborn bearded seal pup, an ice seal, suggesting that floes existed near Unalaska Island as late as April.

Read on » » » »

Methane seekers: Radio reporter Melissa Block, UAF scientist
Katey Walter, and NPR producer Art Silverman
Photo: River Gates of Anchorage

It bubbled. It boiled. It stank.

University of Alaska Fairbanks scientist Katey Walter just wanted to show a National Public Radio news crew a smidgin of methane seeping from a lake on Alaska’s North Slope near Barrow. It’s all part of her investigations into the supergreenhouse gas, and how it oozes into the atmosphere all over the Far North.

Bacteria that digest dead vegetation and other edible gunk on the lake bottom produce methane that gets trapped in the muck, sometimes for eons. When lake-bot