Earth’s Ice Is Melting Much Faster Than Forecast.

Earth’s Ice Is Melting Much Faster Than Forecast.

SOURCE: Garn Press DATE: February 5, 2018 SNIP: The key question, as I see it, is how to project what the sea level will soon be due to ice sheet melting. But this is confounded by us not really knowing what to expect. We keep being surprised by nature being more sensitive and complex. As the science develops, we see more interconnection, where multiplying feedbacks produce surprisingly fast responses. Will there be some saving self-regulation of human-induced climate warming and its melting land ice consequences? The enormous increase of heat in our oceans, from past decades of enhanced greenhouse effect, negates any hope that negative feedbacks or even solar output will prevent a much warmer world. The few negative feedbacks we have found for ice — like more snow as a result of a warming climate, more reflective frost, more efficient sub-glacial water transmission — are clearly being outdone. And at the global scale, despite some negative feedbacks like more clouds, clearly we are not seeing net cooling. Feedbacks, whether positive or negative, only do their thing after the initial effect. Negative feedbacks don’t reverse the perturbation. Seemingly the biggest issue with abrupt sea level rise comes from the now unstoppable loss of key sectors of west Antarctic ice and the discovery of more marine instability than we thought elsewhere. Like glaciers thinning rapidly in east Antarctica. Or in Greenland where improved bedrock maps reveal a marine connection an average of 40 kilometers further inland than previously thought. Or like how new fjord underwater mapping reveals greater fjord depths, increasing the odds that deep warm ocean water can communicate...
Algae Growth Reduces Reflectivity, Enhances Greenland Ice Sheet Melting

Algae Growth Reduces Reflectivity, Enhances Greenland Ice Sheet Melting

SOURCE: American Geophysical Union (AGU) DATE: December 20, 2017 SNIP: New research shows algae growing on the Greenland ice sheet, the Earth’s second-largest ice sheet, significantly reduce the surface reflectivity of the ice sheet’s bare ice area and contribute more to its melting than dust or black carbon. The new findings could influence scientists’ understanding of ice sheet melting and projections of future sea level rise, according to the study’s authors. The new study quantitatively assessed how surface ice algae contribute to darkening of the ice sheet, and found the algae reduce the ice sheet’s albedo significantly more than non-algal materials, like mineral particles and black carbon. Algal darkening is responsible for 5 percent to 10 percent of the total ice sheet melt each summer, according to the new research published in Geophysical Research Letters, a journal of the American Geophysical Union. Absorption of sunlight is responsible for most of the ice melt in Greenland, according to Jason Box, a climatologist at The Geological Survey of Denmark and Greenland and the other lead author of the new study. Microbes such as algal cells colonize the ice and can accumulate over time given enough sunlight, water and nutrients. Surface ice algae produce dark pigments to protect themselves from high intensity radiation, further darkening the sheet surface, Marek Stibal, a cryosphere ecologist at Charles University in Prague, Czech Republic and one of the lead authors of the new study, said. The new study didn’t estimate how much more ice could melt in the future due to algal darkening. But the results can lay the groundwork to devise more accurate projections of...
British Antarctic research station to shut for second winter as cracks in ice grow

British Antarctic research station to shut for second winter as cracks in ice grow

SOURCE: The Guardian DATE: October 31, 2017 SNIP: A British research station in Antarctica is being shut down for the second winter in a row following concerns over growing cracks in the 150-metre thick ice shelf on which it stands. The Halley VI station, which is parked on the Brunt ice shelf, will be shut down between March and November 2018, with the 14-strong staff who had been gearing up for the winter stint redeployed elsewhere in Antarctica or brought home to the UK. The worries are based on two cracks. The first is an ice chasm that began to show movement northwards in 2012, after more than 30 years of dormancy, and has accelerated over the past seven months. The second, north of the research station, has been dubbed the “Halloween crack” after it appeared in October 2016. It is now estimated to be about 50km in length and growing eastwards, crossing a resupply route for the station. “It has grown a couple of kilometres during the winter period,” said Professor David Vaughan, director of science at the British Antarctic Survey, adding that the crack had also...
Worrying new research finds that the ocean is cutting through a key Antarctic ice shelf

Worrying new research finds that the ocean is cutting through a key Antarctic ice shelf

SOURCE: Washington Post DATE: October 11, 2017 SNIP: A new scientific study published Tuesday has found that warm ocean water is carving an enormous channel into the underside of one of the key floating ice shelves of West Antarctica, the most vulnerable sector of the enormous ice continent. The Dotson ice shelf, which holds back two separate large glaciers, is about 1,350 square miles in area and between 1,000 and 1,600 feet thick. But on its western side, it is now only about half that thickness, said Noel Gourmelen, a researcher at the University of Edinburgh in Scotland and the lead author of the research, which was just published in Geophysical Research Letters. The reason is the same one that is believed to be shrinking glaciers and pouring ice into the ocean across West Antarctica — warm ocean water located offshore is now reaching the ice from below. “We think that this channel is actually being carved for the last 25 years,” said Gourmelen, whose research team detected the channel using satellite observations. “It’s been thinning and melting at the base for at least 25 years, and that’s where we are now.” Dotson ice shelf as a whole has been thinning at an average rate of more than eight feet per year since 1994, even as the speed of ice flowing outward through the shelf has increased by 180 percent. But the thinning in the channel has been far greater. The research calculates that 45 feet of ice thickness is being subtracted annually from the channel. The new study calculates that as a result of this highly uneven melting,...
Scientists mapping Greenland have produced some surprising – and worrying – results

Scientists mapping Greenland have produced some surprising – and worrying – results

SOURCE: Washington Post DATE: October 4, 2017 SNIP: Two new studies of Greenland, using sophisticated technologies and large scientific teams to pull together and process the data, have now gone further in taking the full measure of the island through that ever-so-basic scientific act: mapping. The first, a comprehensive seabed mapping project, relying in part on new data from NASA’s OMG (“Oceans Melting Greenland”) mission, concludes that the Greenland ice sheet is far more exposed to the planet’s warming oceans than previously known — and has more ice to give up than, until now, has been recognized. The new research finds that “between 30 and 100% more glaciers are potentially exposed to [warm Atlantic water] than suggested by previous mapping, which represents 55% of the ice sheet’s total drainage area.” In other words, more than half of Greenland’s ice lies in or flows through areas that could be influenced by warming seas. Meanwhile, on Wednesday, a separate team of scientists used another quite different large-scale mapping exercise to document a surprising — but closely related — change in Greenland’s above-water topography. Publishing in the journal Nature, they showed that the contours of the huge island are changing because with all the ice melt rushing from glaciers to the sea, river deltas are expanding outward — a rare occurrence these days when deltas around the world are generally retreating, threatened by rising seas (think of the Mississippi River delta, for instance, and its vanishing wetlands). “Over the period of the 1980s to 2010s, rapid increase of meltwater and sediment fluxes caused dramatic advance of these deltas into the ocean,” said...