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
Tag Archives: oceans
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
14 September 2015, Climate News Network, Southern Ocean starts to soak up carbon again. Scientists report that the great oceanic “lung” is again breathing in vast amounts of carbon dioxide from the atmosphere – but can’t say why or whether it will last. The high seas have begun to respond again to the changes in the atmosphere, with two new studies confirming that the Southern Ocean is absorbing more atmospheric carbon. Levels of carbon dioxide in the atmosphere have been steadily increasing as humans burn ever more fossil fuels, but climate scientists will probably hesitate before exhaling sighs of relief over the latest findings. Rising CO2 in the atmosphere means global warming, which means climate change, melting ice caps, rising sea levels − and even more global warming and climate change. So the discovery that one great stretch of hostile ocean is soaking up more of the stuff sounds like very good news. However, the celebrations are likely to be cautious, as there is no guarantee that the process is permanent. Read More here