14 October 2015, Climate News Network, Antarctic ice shelf melting could double by 2050. Scientists find that the combination of global warming and powerful winds sweeping snow off the ice of Antarctica threatens to speed up sea level rise. Antarctica, the planet’s largest desert, is home to 90% of the world’s ice – enough to raise global sea levels by at least 60 metres. So what happens to its ice and snow is a matter of serious concern to all of us. One group has just predicted that, by 2050, the rate at which the ice shelves melt will double. Another reports that powerful winds are not just shifting Antarctica’s snow, but are also blowing 80 billion tonnes of it away, into the sea or the atmosphere. Both cases exemplify the challenges of climate research and the construction of projections for the future. Inland glaciers Ice shelves are already afloat: if they melt, that will make no difference to sea levels. But floating ice that is fixed to the continental shelf also serves as a brake on the flow of glaciers further inland. So without the ice shelf “doorstops”, these could start to shed ice ever faster, and accelerate sea level rise. Luke Trusel, postdoctoral scholar at the Woods Hole Oceanographic Institutionin the US, and colleagues report in Nature Geoscience that they foresee a doubling of surface melting of the ice shelves by 2050. If greenhouse gas emissions from fossil fuel combustion continue at the present rate, by 2100 the melting may surpass the levels associated with collapse of the shelves. Read More here
Category Archives: Impacts Observed & Projected
12 October 2015, Washington Post, Why the Earth’s past has scientists so worried about the Atlantic Ocean’s circulation. In the last month, there’s been much attention to a cool patch in the North Atlantic Ocean, where record cold temperatures over the past eight months present a stark contrast to a globe that is experiencing record warmth. And although there is certainly no consensus on the matter yet, some scientists think this pattern may be a sign of one long-feared consequence of climate change — a slowing of North Atlantic ocean circulation, due to a freshening of surface waters. The cause, goes the thinking, would be the rapidly melting Greenland ice sheet, whose large freshwater flows may weaken ocean “overturning” by reducing the density of cold surface waters (colder, salty water is denser). If cold, salty waters don’t sink in the North Atlantic and flow back southward toward Antarctica at depth, then warm surface waters won’t flow northward to take their place. The result could be a significant change to northern hemisphere climate, as less ocean-borne heat reaches higher latitudes. Read More here
12 October 2015, Yale Environment 360, The Rapid and Startling Decline Of World’s Vast Boreal Forests. Scientists are becoming increasingly concerned about the fate of the huge boreal forest that spans from Scandinavia to northern Canada. Unprecedented warming in the region is jeopardizing the future of a critical ecosystem that makes up nearly a third of the earth’s forest cover. The boreal forest wraps around the globe at the top of the Northern Hemisphere in North America and Eurasia. Also known as taiga or snow forest, this landscape is characterized by its long, cold and snowy winters. In North America it extends from the Arctic Circle of northern Canada and Alaska down into the very northern tip of the United States in Idaho, Washington, Montana, and Minnesota. It’s the planet’s single largest biome and makes up 30 percent of the globe’s forest cover. Moose are the largest ungulate in the boreal, adapted with their long legs to wade in its abundant marshes, lakes and rivers eating willows, aspen and other plants. In the southern boreal forest of northern Minnesota, moose were once plentiful, but their population has plummeted. Thirty years ago, in the northwest part of the state, there were some 4,000; they now number about a hundred. In the northeast part, they have dropped from almost 9,000 to 4,300. They’ve fallen so far, so fast that some groups want them listed as endangered in the Midwest. Read More here
8 October 2015, TomDispatch, Welcome to a New Planet Climate Change “Tipping Points” and the Fate of the Earth By Michael T. Klare. Not so long ago, it was science fiction. Now, it’s hard science — and that should frighten us all. The latest reports from the prestigious and sober Intergovernmental Panel on Climate Change (IPCC) make increasingly hair-raising reading, suggesting that the planet is approaching possible moments of irreversible damage in a fashion and at a speed that had not been anticipated. Scientists have long worried that climate change will not continue to advance in a “linear” fashion, with the planet getting a little bit hotter most years. Instead, they fear, humanity could someday experience “non-linear” climate shifts (also known as “singularities” or “tipping points”) after which there would be sudden and irreversible change of a catastrophic nature. This was the premise of the 2004 climate-disaster film The Day After Tomorrow. In that movie — most notable for its vivid scenes of a frozen-over New York City — melting polar ice causes a disruption in the North Atlantic Current, which in turn triggers a series of catastrophic storms and disasters. At the time of its release, many knowledgeable scientists derided the film’s premise, insisting that the confluence of events it portrayed was unlikely or simply impossible. Fast forward 11 years and the prospect of such calamitous tipping points in the North Atlantic or elsewhere no longer looks improbable. In fact, climate scientists have begun to note early indicators of possible catastrophes. Read More here