15 October 2015, The Conversation, Death of a landscape: why have thousands of trees dropped dead in New South Wales? Trees die – that’s a fact of life. But is the death of an entire iconic landscape of Eucalyptus in the Cooma-Monaro region of New South Wales natural? For over a decade, large stands of Eucalyptus viminalis, commonly known as Ribbon Gum or Manna Gum, have been gradually declining in health, and now stand like skeletons in huge tree graveyards. In our recently published survey we found the affected area to cover almost 2,000 square km, about the size of the area burnt in the devastating Ash Wednesday bushfires in Victoria or more than the area covered by the 2003 Canberra fires. Within this area, almost every Ribbon Gum is either dead or showing signs of severe stress and dieback, with thinning crowns full of dead branches. Other tree species seem to be surviving, but this smooth-barked gum with its characteristic ribbons of peeling park, once the dominant tree of the Monaro, now seems set to disappear from the landscape. Read More here
Category Archives: Impacts Observed & Projected
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
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