28 May 2017, Climate News Network, Antarctica heights settle polar warming puzzle. Computer simulation shows that Antarctica is warming far slower than the Arctic region because of its much greater height. Scientists believe they have settled one of the great polar puzzles − why Antarctica is warming at a rate so much slower than the Arctic region. And the answer is a simple one: Antarctica is so much higher. To ram the point home, they used a computer simulation to hammer the entire southern continent until it was no more than a metre above sea level. At which point, in their simulation, warming at the South Pole became much more dramatic. The two poles are very different: the Arctic is an ocean almost entirely surrounded by land, while Antarctica is a vast continent entirely surrounded by frozen ocean. Landmass of ice As the north polar ocean ice melts, dark seas begin to absorb more radiation. In the southern hemisphere, the landmass of ice reflects radiation back into space to insulate the continent and keep its temperatures far below freezing. But the new study published in Earth System Dynamics journal shows that what makes the biggest difference is the elevation of the surface. Antarctica is not just an enormous continent: thanks to many millions of years of snowfall at very low temperatures, it is banked high with ancient ice. Its average elevation is 2,500 metres − far higher than the highest peaks in the UK, for example − and its highest mountain, Mount Vinson, reaches 4,892 metres, which is higher than any alpine peak in Europe. Evidence from the distant past and climate models both show that, in a warming world, the poles should warm faster than the rest of the planet. But while the Arctic is warming at twice the rate of the rest of the globe, change in Antarctica has been much more sluggish. Read More here
Tag Archives: Antarctica
27 May 2017, Climate News Network, Climate change is turning Antarctic green.Plant life is flourishing on the Antarctic Peninsula, indicating a dramatic increase in the rate of warming due to climate change. Antarctica is getting greener. British biologists have documented a four-fold or even five-fold increase in plant growth on the Antarctic Peninsula. They identify the sudden burgeoning of green things as an indicator that the continent is responding to climate change. In fact, only a tiny fraction of the south polar land mass is home to any plant life, but the first explorers observed mosses growing on the 600km of the peninsula.Antarctic climate In a climate in which temperatures rarely go much higher than freezing, mosses grow slowly – and hardly ever decompose. So any mossy bank becomes a reliable record of shifts in climate dating back thousands of years. Researchers from the University of Exeter in the UK, and colleagues from the University of Cambridge and the British Antarctic Survey, report in Current Biology that they tested five ice cores from three sites and found major biological changes had occurred over the past 50 years right across the Antarctic Peninsula. “Temperature increases over roughly the past half-century on the Antarctic Peninsula have had a dramatic effect on moss banks growing in the region” The Arctic has entered a phase of dramatic warming: researchers have documented the advance of green growth across the tundra and even the advance of exotic infections in the animal population. Warming in the southern continent has been much more sluggish, but, even in the frozen interior, melting has been observed. And where there is sunlight and liquid water and bare rock, there are the conditions for green growth. Read More here
18 May 2017, New York Times Antarctic Dispatches: Miles of Ice Collapsing Into the Sea. The acceleration is making some scientists fear that Antarctica’s ice sheet may have entered the early stages of an unstoppable disintegration. Because the collapse of vulnerable parts of the ice sheet could raise the sea level dramatically, the continued existence of the world’s great coastal cities — Miami, New York, Shanghai and many more — is tied to Antarctica’s fate. Four New York Times journalists joined a Columbia University team in Antarctica late last year to fly across the world’s largest chunk of floating ice in an American military cargo plane loaded with the latest scientific gear. Inside the cargo hold, an engineer with a shock of white hair directed younger scientists as they threw switches. Gravity meters jumped to life. Radar pulses and laser beams fired toward the ice below. On computer screens inside the plane, in ghostly traces of data, the broad white surface of the Ross Ice Shelf began to yield the secrets hiding beneath. Read More here
12 April 2017, Nature, Antarctica’s sleeping ice giant could wake soon. The massive East Antarctic Ice Sheet looks stable from above — but it’s a dangerously different story below. These first direct observations confirmed a fear that researchers had long harboured: that warm waters from the surrounding ocean can sneak underneath the floating glacier tongue and eat the ice away from below1. “This could explain why Totten has been thinning in the past few decades,” says Rintoul. Findings such as these are revealing some scary truths about East Antarctica — the vast, remote landmass to the east of the Transantarctic Mountains (see ‘Ice king’). This region is about as big as the entire United States and the majority of it stands on a high plateau up to 4,093 metres above sea level, where temperatures can plunge to −95 °C. Because the East Antarctic Ice Sheet seems so cold and isolated, researchers thought that it had been stable in the past and was unlikely to change in the future — a stark contrast to the much smaller West Antarctic Ice Sheet, which has raised alarms because many of its glaciers are rapidly retreating. In the past few years, however, “almost everything we thought we knew about East Antarctica has turned out to be wrong”, says Tas van Ommen, a glaciologist at the Australian Antarctic Division in Kingston, near Hobart. By flying across the continent on planes with instruments that probe beneath the ice, his team found that a large fraction of East Antarctica is well below sea level, which makes it more vulnerable to the warming ocean than previously thought. The researchers also uncovered clues that the massive Totten glacier, which holds about as much ice as West Antarctica, has repeatedly shrunk and grown in the past2 — another sign that it could retreat in the future. Read More here