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
Category Archives: Impacts Observed & Projected
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
8 October 2015, Science Daily, NOAA declares third ever global coral bleaching event, Bleaching intensifies in Hawaii, high ocean temperatures threaten Caribbean corals. As record ocean temperatures cause widespread coral bleaching across Hawaii, NOAA scientists confirm the same stressful conditions are expanding to the Caribbean and may last into the new year, prompting the declaration of the third global coral bleaching event ever on record. Waters are warming in the Caribbean, threatening coral in Puerto Rico and the U.S. Virgin Islands, NOAA scientists said. Coral bleaching began in the Florida Keys and South Florida in August, but now scientists expect bleaching conditions there to diminish. “The coral bleaching and disease, brought on by climate change and coupled with events like the current El Niño, are the largest and most pervasive threats to coral reefs around the world,” said Mark Eakin, NOAA’s Coral Reef Watch coordinator. “As a result, we are losing huge areas of coral across the U.S., as well as internationally. What really has us concerned is this event has been going on for more than a year and our preliminary model projections indicate it’s likely to last well into 2016.” While corals can recover from mild bleaching, severe or long-term bleaching is often lethal. After corals die, reefs quickly degrade and the structures corals build erode. This provides less shoreline protection from storms and fewer habitats for fish and other marine life, including ecologically and economically important species. This bleaching event, which began in the north Pacific in summer 2014 and expanded to the south Pacific and Indian oceans in 2015, is hitting U.S. coral reefs disproportionately hard. NOAA estimates that by the end of 2015, almost 95 percent of U.S. coral reefs will have been exposed to ocean conditions that can cause corals to bleach. Read More here