Global Warming

Warming Greenland ice sheet passes point of no return

Nearly 40 years of satellite data from Greenland shows that glaciers on the island have shrunk so much that even if global warming were to stop today, the ice sheet would continue shrinking.

The finding, published today, Aug. 13, in the journal Nature Communications Earth and Environment, means that Greenland’s glaciers have passed a tipping point of sorts, where the snowfall that replenishes the ice sheet each year cannot keep up with the ice that is flowing into the ocean from glaciers.

Climate change, not hunters, may have killed off woolly rhinos

Rather than getting wiped out by Ice Age hunters, woolly rhinos charged to extinction in Siberia around 14,000 years ago when the climate turned warm and wet, a study of ancient DNA suggests.

Numbers of breeding woolly rhinos stayed relatively constant for tens of thousands of years until at least about 18,500 years ago, more than 13,000 years after people first reached northeastern Siberia, scientists report online August 13 in Current Biology. Yet only a few thousand years later, woolly rhinos died out, probably because temperatures had risen enough to reshape arctic habitats. A shift to warm, rainy conditions, which occurred between roughly 14,600 and 12,800 years ago, likely played a large role in the rapid decline of this cold-adapted species.

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Tropical Soil Leaks CO2

Tropical forest soil warmed in experiments to levels consistent with end-of-century temperature projections released 55 percent more CO2 than control plots, exposing a previously underestimated source of greenhouse gas emissions, researchers reported Wednesday.

Before humanity began loading the atmosphere with carbon pollution by burning fossil fuels, the input and outflow of CO2 into soil – one key element in Earth’s complex carbon cycle – remained roughly in balance.

Gases emitted by deadwood and decaying leaves, in other words, were cancelled out by microorganisms that feed on such matter. But climate change has begun to upset that balance, according to a new study, published in Nature.

In experiments, researchers placed heating rods in a one-hectare plot of undisturbed primary forest on Barro Colorado Island, Panama. They warmed the soil to a depth of just over one metre (three feet) by 4C over a period of two years. The findings shows an increase in in the release of CO2 of 55 per cent above the basal rates.

Nature – Images

Interesting Images

Giant ice-filled crater on Mars – An 82 kilometre-wide crater on Mars that may be topped with snow has been photographed by the ESA’s (European Space Agency) Mars Express.

The stunning untrodden snow scene comes as the mission prepares to celebrate 15-years since it entered the Red Planet’s orbit on Christmas Day. Korolev, as the crater is known, is thought to be 1.8 kilometres deep, filled with around 2,200 cubic kilometres of ice.

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Nature – Images

Interesting Images

NASA scientists flying over the Arctic earlier this month spotted strange shapes out the window, but they aren’t sure what caused them.

Three holes dot the sea ice, seen from the window of a NASA aircraft in the photo above, taken April 14. They’re clustered together, each surrounded by one or two radiating layers of ridged, textured ice, almost as if a batch of archery targets had melted and gone lopsided. All around them are bumpy formations that mean the ice is thin and relatively new.

It’s possible, NASA wrote, that some large mammal took advantage of that thin ice to poke holes through it to breathe.Ring sealsand harp seals are both known to poke holes through the ice that look somewhat similar to this.

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Space Events

Big Sheets of Water Ice on Mars

Sizable deposits of water ice lurk just beneath the surface in some regions of Mars, a new study reports.

The newfound sheets appear to contain distinct layers, suggesting that studying them could shed considerable light on the Red Planet’s climate history, researchers said. And the ice is buried by just a few feet of Martian dirt in places, meaning it might be accessible to future crewed missions.

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Nature – Images

Interesting Images

Rare ‘Dragon-Skin’ Ice Spotted During Antarctic Research Voyage. “Dragon skin” had not been seen in Antarctica since 2007, according to researchers.

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Global Warming

Antarctica is gaining ice: NASA

An increase in Antarctic snow accumulation that began 10,000 years ago is currently adding enough ice to the continent to outweigh the increased losses from its thinning glaciers.

Areas of the continent like the Antarctic peninsula have increased their mass loss in the last decades, says a new NASA study.

The research challenges the conclusion of other studies, including Intergovernmental Panel on Climate Change’s 2013 report which says that Antarctica is overall losing land ice.

According to the analysis of satellite data, the Antarctic ice sheet showed a net gain of 112 billion tonnes of ice a year from 1992 to 2001. The net gain slowed to 82 billion tonnes of ice per year between 2003 and 2008.

“We are essentially in agreement with other studies that show an increase in ice discharge in the Antarctic peninsula and the Thwaites and Pine Island region of West Antarctica,” explained Jay Zwally, glaciologist with NASA Goddard Space Flight Centre in Greenbelt, Maryland.

Our main disagreement is for East Antarctica and the interior of West Antarctica. “Here, we see an ice gain that exceeds the losses in the other areas,” he added. But it might take a few decades for Antarctica’s growth to reverse, according to Zwally.

The study analysed changes in the surface height of the Antarctic ice sheet measured by radar altimeters on two European Space Agency satellites and by the laser altimeter on NASA’s Ice, Cloud, and land Elevation Satellite (ICESat).

“At the end of the last Ice Age, the air became warmer and carried more moisture across the continent, doubling the amount of snow dropped on the ice sheet,” Zwally noted.

“The good news is that Antarctica is not currently contributing to sea level rise, but is taking 0.23 mm per year away,” Zwally said. But this is also bad news.

“If the 0.27 mm per year of sea level rise attributed to Antarctica in the IPCC report is not really coming from Antarctica, there must be some other contribution to sea level rise that is not accounted for,” he pointed out in the study which appeared in the Journal of Glaciology.

Global Warming

Arctic Ice Snow Cover Disappearing

The depth of the late-winter snowpack on sea ice in the Arctic has thinned considerably over the past 70 years, according to a new University of Washington-NASA study.

Writing for the Journal of Geophysical Research: Oceans, lead author Melinda Webster says the conclusion was made after combining data collected by ice buoys and NASA aircraft with historical records gathered by Soviet scientists from the 1950s through the early 1990s.

Those measurements show the snowpack has thinned from 14 inches to 9 inches in the western Arctic and from 13 inches to 6 inches in the Beaufort and Chukchi seas, north and west of Alaska.

“This confirms and extends the results of that earlier work, showing that we continue to see thinning snow on the Arctic sea ice,” said Ignatius Rigor, who was also a co-author on the earlier paper.

The authors believe the snowpack could be thinner because the surface of the Arctic Ocean is freezing later, after some of the year’s heaviest snowfalls in September and October.

That snow is now falling on a mainly open ocean.

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Environment

Great Lakes Are Ice-Free at Last

After seven chilling months across the North American Great Lakes, winter’s grip on the region has finally ended.

With only days before the official start of summer, all five lakes became clear of the ice, which at one point in early March covered more than 92 percent of their combined surfaces.

That was the second-highest coverage on record, according to the Great Lakes Environmental Research Laboratory.

Temperatures in the 80s helped finish off the few floating chunks that remained after the more than 2,000 hours of ice-clearing efforts by the U.S. Coast Guard this spring.

The last surviving chunk was on Lake Superior, near Marquette, Michigan.

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Environment

Moss reanimates after 400 years in Deep Freeze

Ancient plants have been brought back to life, despite having been frozen inside a glacier for over 400 years.

Researcher Catherine La Farge, director and curator of the Cryptogamic Herbarium at the University of Alberta, snagged moss which carbon-dating estimated was aged between 400 and 600 years old, frozen during the “Little Ice Age” between 1550 and 1850.

The scientists picked the plants from an area around the Teardrop Glacier in the Canadian Arctic, because La Farge noticed that some of them appeared to be regrowing once the ice had retreated. Glaciers in the region have been receding at a rate of around three to four metres a year, uncovering land that hasn’t seen the Sun since the 1500s.

Once they got the plants back to the lab, La Farge and her co-authors successfully regenerated four species from the original parent material in 11 cultures from seven subglacial samples.

Frozen moss revived

Environment

Global Warming – Seas Freeze More Off Antarctica

One of the apparent contradictions of global warming is the increased melting of ice in the Arctic, but in Antarctica the extent of ice cover is increasing. A recent study looks for answers.

It seems that global warming is expanding the extent of sea ice around Antarctica in winter in a paradoxical shift caused by cold plumes of summer melt water that re-freeze fast when temperatures drop. Melted ice re-freezes faster than sea water in winter.

An increasing summer thaw of ice on the edges of Antarctica, twinned with less than expected snowfall on the frozen continent, is also adding slightly to sea level rise in a threat to low-lying areas around the world.

Climate scientists have been struggling to explain why sea ice around Antarctica has been growing, reaching a record extent in the winter of 2010, when ice on the Arctic Ocean at the other end of the planet shrank to a record low in 2012.

“Sea ice around Antarctica is increasing despite the warming global climate,” said Richard Bintanja, lead author of the study at the Royal Netherlands Meteorological Institute. “This is caused by melting of the ice sheets from below.”.

Ice is made of fresh water and, when ice shelves on the fringes of Antarctica thaw in summer because of upwellings of warming sea water, the meltwater forms a cool layer that floats on the denser, warmer salty sea water below.

In winter, the melt water readily turns to ice because it freezes at zero degrees Celsius, above sea water at -2C (28.4F).

At a winter maximum in September, ice on the sea around Antarctica covers about 19 million sq kms (7.3 million sq miles), bigger than Antarctica’s land area. It then melts away into the ocean as summer approaches.

On the other hand, among other scientists, Paul Holland of the British Antarctic Survey stuck to his findings last year that a shift in winds linked to climate change was blowing a layer of melt water further out to sea and this was adding to winter ice.

Rescue

Russian sailors rescue this dog stranded on a small iceberg:

 

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Environment

Cold in Ontario, Canada.

Stunning image of frozen trees on the shore of Lake Ontario. Captured by photographer Timothy Corbin.

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Environment

Ice-Free Arctic Ocean in 2030?

Vast uncertainty remains over the causes of melting Arctic sea ice and when it may disappear altogether during the summer, which would have consequences for oil explorers, shipping firms and the fight against climate change.

The answer will depend on the balance of natural and manmade causes.

Last September sea ice reached its lowest level in the satellite record, which dates back to 1979, a development that has implications for local native communities and wildlife, local coastal erosion and possibly northern hemisphere weather.

Under the albedo effect, dry snow reflects more than 80 percent of solar radiation; bare ice 65 percent; and open water just 5 percent.

And increasing expanse of open water each summer warms up faster than ice-covered sea, meaning new ice will be thinner and more vulnerable the following year.

There are various underlying causes of the melt.

Rising greenhouse gas emissions drive up air and sea temperatures.

Water from a warmer Atlantic entering the Arctic Ocean through the Fram Strait between eastern Greenland and Svalbard, an island due north of Norway.

A similar inflow of warmer Pacific water through the Bering Strait has long been identified as an important process that causes the thinning of ice in the central Arctic.

There are also weather effects that may be natural, partly natural or entirely due to greenhouse gas emissions affecting Arctic ice.

A particular weather pattern contributed to a big melt six years ago by sending warm air towards the central Arctic, according to researchers from the Netherlands, Sweden and Germany.

The cumulative impact from rising greenhouse gas emissions, which combined with a few freak summers, ice export and the albedo effect could finish off summer sea ice rather quickly.

Increasingly, scientists and researchers are coming to believe that a seasonally ice-free Arctic Ocean might be realized as early as 2030.