Arctic carbon cycle is speeding up

Arctic carbon cycle is speeding up

SOURCE: NASA DATE: August 3, 2018 SNIP: A new NASA-led study using data from the Arctic Boreal Vulnerability Experiment (ABoVE) shows that carbon in Alaska’s North Slope tundra ecosystems spends about 13 percent less time locked in frozen soil than it did 40 years ago. In other words, the carbon cycle there is speeding up — and is now at a pace more characteristic of a North American boreal forest than of the icy Arctic. “Warming temperatures mean that essentially we have one ecosystem — the tundra — developing some of the characteristics of a different ecosystem — a boreal forest,” said study co-author Anthony Bloom of NASA’s Jet Propulsion Laboratory in Pasadena, California. “While various factors regulate how fast this transformation will continue to occur, studies using Landsat and MODIS satellite imagery with field measurements over the past decades have observed a northward migration of shrubs and trees.” And it’s not just about the trees. The Arctic carbon cycle is a delicate balance of carbon being released into the atmosphere and carbon being removed from the atmosphere. Disruptions to this balance have implications well beyond the Arctic. During Arctic summer, warmer temperatures thaw the uppermost layers of permafrost, allowing microbes to break down previously frozen organic matter.This process releases carbon dioxide into the atmosphere. Plant growth also increases during this period – and plants remove carbon dioxide from the atmosphere through photosynthesis. But as temperatures increase, the amount of time carbon is stored in the Arctic soil decreases. “The balance between these two dynamics will determine whether Arctic ecosystems will ultimately remove or add atmospheric carbon dioxide in...
A huge stretch of the Arctic ocean is turning into the Atlantic right before our eyes

A huge stretch of the Arctic ocean is turning into the Atlantic right before our eyes

SOURCE: Washington Post DATE: June 26, 2018 SNIP: Scientists studying one of the fastest-warming regions of the global ocean say changes in this region are so sudden and vast that in effect, it will soon be another limb of the Atlantic, rather than a characteristically icy Arctic sea. The northern Barents Sea, to the north of Scandinavia and east of the remote archipelago of Svalbard, has warmed extremely rapidly — by 2.7 degrees Fahrenheit just since the year 2000 — standing out even in the fastest warming part of the globe, the Arctic. [T]his warming is being accompanied by a stark change of character, as the Atlantic Ocean is in effect taking over the region and converting it into a very different entity. While the Southern Barents is milder, the northern Barents has — until recently — had all the characteristics of an Arctic sea. It featured floating sea ice that, when it melted, helped to provide an icy, freshwater cap atop the ocean. This kept internal heat from escaping to the atmosphere, and also kept the ocean “stratified” — cold, fresher waters at the surface and warmer, Atlantic-originating waters down below. This situation, which obtains in much of the Arctic, was reinforced by the fact that freshwater is less dense than salt water, preserving stratification. But that’s changing. Less sea ice is floating down through the northern Barents Sea from higher Arctic latitudes, the research shows. Indeed, the lack of sea ice in the northern Barents Sea has been a regular feature of charts lately — at this very moment, an enormous stretch of ocean in this area...
In the Arctic, the Old Ice Is Disappearing

In the Arctic, the Old Ice Is Disappearing

SOURCE: New York Times DATE: May 14, 2018 SNIP: In the Arctic Ocean, some ice stays frozen year-round, lasting for many years before melting. But this winter, the region hit a record low for ice older than five years. This, along with a near-record low for sea ice over all, supports predictions that by midcentury there will be no more ice in the Arctic Ocean in summer. As darker, heat-absorbing water replaces reflective ice, it hastens warming in the region. Older ice is generally thicker than newer ice and thus more resilient to heat. But as the old ice disappears, the newer ice left behind is more vulnerable to rising temperatures. “First-year ice grows through winter and then to up to a maximum, which is usually around in March,” said Mark A. Tschudi, a research associate at the Colorado Center for Astrodynamics Research at the University of Colorado, Boulder. “As summer onsets, the ice starts to melt back.” Some of the new ice melts each summer, but some of it lingers to grow thicker over the following winter, forming second-year ice. The next summer, some of that second-year ice survives, then grows even thicker and more resilient the next winter, creating what is known as multiyear ice. Some ice used to last more than a decade. Today, Arctic sea ice is mostly first-year ice. While the oldest ice has always melted when currents pushed it south into warmer waters, now more of the multiyear ice is melting within the Arctic Ocean, leaving more open water in its wake. “I’ve been on record saying that it may be 2030 that...
‘We’ve fallen off a cliff’: Scientists have never seen so little ice in the Bering Sea in spring

‘We’ve fallen off a cliff’: Scientists have never seen so little ice in the Bering Sea in spring

SOURCE: Seattle Times DATE: May 3, 2018 SNIP: In the middle of February, one-third of the ice covering the Bering Sea off Alaska’s West Coast vanished within a week when an enormous pulse of heat swept over the Arctic. Scientists were stunned. This rapid meltdown precipitated a record-shattering decline in Bering Sea ice through the winter and into spring, which has threatened the very way of life in Alaska’s coastal villages — reliant on the ice cover for navigation and hunting. February and March ice levels were as low as far back as scientists can reconstruct, dating back more than 160 years. Now, the ice is almost entirely gone — just 10 percent of normal levels as of the end of April. “We’ve fallen off a cliff: very little sea ice remains in the Bering Sea,” tweeted Rick Thoman, an Alaska-based climatologist with the National Oceanic and Atmospheric Administration, on April 29. The ice extent over the Chukchi Sea, just north of the Bering Sea abutting Alaska’s northwest coast, is also abnormally depleted. It recently began its melt season earlier than ever before...
Shock and Thaw—Alaskan Sea Ice Just Took a Steep, Unprecedented Dive

Shock and Thaw—Alaskan Sea Ice Just Took a Steep, Unprecedented Dive

SOURCE: Scientific American DATE: May 2, 2018 SNIP: Winter sea ice cover in the Bering Sea did not just hit a record low in 2018; it was half that of the previous lowest winter on record (2001), says John Walsh, chief scientist of the International Arctic Research Center at the University of Alaska Fairbanks. “There’s never ever been anything remotely like this for sea ice” in the Bering Sea going back more than 160 years, says Rick Thoman, an Alaska-based climatologist with the National Oceanic and Atmospheric Administration. [T]his year sea-ice coverage as of late April was more like what would be expected for mid-June, well into the melt season. These conditions are the continuation of a winter-long scarcity of sea ice in the Bering Sea—a decline so stark it has stunned researchers who have spent years watching Arctic sea ice dwindle due to climate change. The occurrence of these unusual conditions off Alaska this past winter can largely be chalked up to the random weather variations in a chaotic climate system, Bond, Walsh and Thoman all say—but they add that global warming likely amped up the severity of the situation. Because of the role the weather plays, though, “every year is not going to be like this,” Thoman says. “Next year will almost certainly not be this low.” But as temperatures continue to rise, he says, “odds are very strong that we will not go another 160 years before we see something like this” happen...