Arctic greening thaws permafrost, boosts runoff

Arctic greening thaws permafrost, boosts runoff

SOURCE: Los Alamos National Laboratory DATE: October 17, 2018 SNIP: A new collaborative study has investigated Arctic shrub-snow interactions to obtain a better understanding of the far north’s tundra and vast permafrost system. Incorporating extensive in situ observations, Los Alamos National Laboratory scientists tested their theories with a novel 3D computer model and confirmed that shrubs can lead to significant degradation of the permafrost layer that has remained frozen for tens of thousands of years. These interactions are driving increases in discharges of fresh water into rivers, lakes and oceans. “The Arctic is actively greening, and shrubs are flourishing across the tundra. As insulating snow accumulates atop tall shrubs, it boosts significant ground warming,” said Cathy Wilson, Los Alamos scientist on the project. “If the trend of increasing vegetation across the Arctic continues, we’re likely to see a strong increase in permafrost...
Plankton moving into Arctic waters previously covered with ice could have ‘drastic consequences’

Plankton moving into Arctic waters previously covered with ice could have ‘drastic consequences’

SOURCE: The Independent DATE: October 17, 2018 SNIP: Declining Arctic sea ice is allowing phytoplankton blooms, made up of billions of microscopic plant organisms, to expand northwards into ice-free waters where they have never been seen before, scientists have discovered. Research based on satellite images showing ocean colours reveals vast spring blooms of phytoplankton in the Arctic ocean where blooms were previously non-existent, which are expanding northwards at a rate of one degree of latitude per decade. The team found overall primary production of the phytoplankton in the Arctic Ocean, which has previously been low, increased by 31 per cent between 2003 and 2013. As climate change impacts levels of sea ice, less cover will allow the trend to increase further. Larger spring blooms mean phytoplankton will compete for light and nutrients with other species, hugely altering an ecosystem which has never been free of ice cover. “If the ice pack totally disappears in summer, there will be consequences for the phytoplankton spring bloom,” said Sophie Renaut, a PhD student at Laval University in Quebec City, Canada, and lead author of the study. “We cannot exactly predict how it will evolve, but we’re pretty sure there are going to be drastic consequences for the entire...
Arctic ice sets speed limit for major ocean current

Arctic ice sets speed limit for major ocean current

SOURCE: MIT News DATE: October 17, 2018 SNIP: The Beaufort Gyre is an enormous, 600-mile-wide pool of swirling cold, fresh water in the Arctic Ocean, just north of Alaska and Canada. In the winter, this current is covered by a thick cap of ice. Each summer, as the ice melts away, the exposed gyre gathers up sea ice and river runoff, and draws it down to create a huge reservoir of frigid fresh water, equal to the volume of all the Great Lakes combined. Scientists at MIT have now identified a key mechanism, which they call the “ice-ocean governor,” that controls how fast the Beaufort Gyre spins and how much fresh water it stores. In a paper published today in Geophysical Research Letters, the researchers report that the Arctic’s ice cover essentially sets a speed limit on the gyre’s spin. If global temperatures continue to climb, the researchers expect that the mechanism governing the gyre’s spin will diminish. With no governor to limit its speed, the researchers say the gyre will likely transition into “a new regime” and eventually spill over, like an overflowing bathtub, releasing huge volumes of cold, fresh water into the North Atlantic, which could affect the global climate and ocean circulation. Marshall and Meneghello note that, as Arctic temperatures have risen in the last two decades, and summertime ice has shrunk with each year, the speed of the Beaufort Gyre has increased. Its currents have become more variable and unpredictable, and are only slightly slowed by the return of ice in the winter. “At some point, if this trend continues, the gyre can’t swallow all...
Sea ice in the central Arctic should be growing. It’s not.

Sea ice in the central Arctic should be growing. It’s not.

SOURCE: Mashable DATE: October 11, 2018 SNIP: In the deep middle of the remote Arctic Ocean, things are amiss. With the passage of summer, the ice — diminished by the warm season — is expected to regrow as frigid temperatures envelope the Arctic. But, this year, it’s not. Specifically, sea ice in the Central Arctic basin — a massive region of ocean some 4.5 million square kilometers in size — hasn’t started its usual rapid expansion, and unusually warm temperatures in both the air and the ocean are largely to blame. “For the most part, Arctic sea ice normally begins rapidly refreezing this time of year,” Zack Labe, a climate scientist and Ph.D. candidate at the University of California Irvine, said over email. In mid-October, the temperatures here should be plummeting. But they’ve gone up. “Both the ocean and atmosphere are warmer than usual,” said Lars Kaleschke, an Arctic scientist at the University of Hamburg’s Center for Earth System Research and...
As Greenland Warms, Nature’s Seasonal Clock Is Thrown Off-Kilter

As Greenland Warms, Nature’s Seasonal Clock Is Thrown Off-Kilter

SOURCE: Yale e360 DATE: September 13, 2018 SNIP: From their perch on a rocky ridge in southwestern Greenland, graduate students Rebecca Walker and Conor Higgins peer through binoculars, looking for caribou. It’s a cool, June day and the tundra is ablaze with tiny magenta, pink, and yellow wildflowers. Crystalline lakes dot the glacially carved valleys, and from the round-topped mountains you can catch the glint of the massive Greenland Ice Sheet to the east. Below, the Watson River tumbles toward Kangerlussuaq Fjord, 12 miles to the west. It’s quiet, save for bird song, the rush of the wind, and the frequent crash of ice shearing off nearby Russell Glacier. Two decades ago, Walker and Higgins would have seen hundreds of caribou from the top of this same hill, set amid an ancestral caribou calving grounds. But these days the herds are a fraction of their former size, and Walker and Higgins spot only a handful of females and two calves a mile away. The ecologist supervising the students — Eric Post of the University of California, Davis — says the decline is very likely linked to a rapidly warming climate that is driving the schedules of caribou and the tundra plants they eat seriously out of balance. Post first came to the area 25 years ago to study calving in large herds of caribou. But around the early 2000s, he began noticing a major change. “As it got warmer and warmer and the growth season started earlier and earlier, the caribou calving season wasn’t starting earlier to the same extent,” Post says. The advancing plant growth was being triggered...