8 June 2016, Climate News Network, Puzzle of Antarctica’s long-term ice loss. Analysis of satellite data records reveals that the worrying loss of hundreds of square kilometres of ice along West Antarctica’s coastline has been occurring for decades. Parts of Antarctica are not only losing ice to the ocean, they have been doing so for 40 years. Geoscientists from the University of Edinburgh and a US colleague report in Geophysical Research Letters that they looked at satellite imagery of West Antarctica’s coastline along a 2,000 km stretch and found that the region has lost 1,000 square kilometres of ice in four decades. The surprise is not that melting occurs, but that it has been happening for such a long time. Frazer Christie, a PhD student, and partners analysed data from NASA, the US Geological Survey and the European Space Agency to find that ice has been retreating along almost the entire coast of Antarctica’s Bellingshausen Sea since satellite records began. Some of the largest changes – where ice has thinned rapidly and retreated several kilometres since 1975 – matched those places where the ice front is deepest. “We knew that ice had been retreating from this region recently, but now, thanks to a wealth of freely available satellite data, we know this has been occurring pervasively along the coastline for almost half a century,” Christie says. Colder water He and his colleagues blame warmer ocean waters, rather than warmer atmosphere.But, paradoxically, a study from the University of Washington in Seattle, US, reports that the waters lapping the continent are not warming substantially − because of a steady upwelling of much colder water from the depths of the Southern Ocean. Read More here
Tag Archives: oceans
7 June 2016, Washington Post, ‘We’ve never seen anything like this’: Arctic sea ice hit a stunning new low in May. The 2016 race downward in Arctic sea ice continued in May with a dramatic new record. The average area of sea ice atop the Arctic Ocean last month was just 12 million square kilometers (4.63 million square miles), according to the National Snow and Ice Data Center (NSIDC). That beats the prior May record (from 2004) by more than half a million square kilometers, and is well over a million square kilometers, or 500,000 square miles, below the average for the month. Another way to put it is this: The Arctic Ocean this May had more than three Californias less sea ice cover than it did during an average May between 1981 and 2010. And it broke the prior record low for May by a region larger than California, although not quite as large as Texas. This matters because 2016 could be marching toward a new record for the lowest amount of ice ever observed on top of the world at the height of melt season — September. The previous record September low was set in 2012. But here’s what the National Snow and Ice Data Center has to say about that: Daily extents in May were also two to four weeks ahead of levels seen in 2012, which had the lowest September extent in the satellite record. The monthly average extent for May 2016 is more than one million square kilometers (386,000 square miles) below that observed in May 2012.In other words, for Arctic sea ice, May 2016 was more like June 2012 — the record-breaking year. Going into the truly warm months of the year, then, the ice is in a uniquely weak state. “We’ve never seen anything like this before,” said Mark Serreze, who directs the center. “It’s way below the previous record, very far below it, and we’re something like almost a month ahead of where we were in 2012.” Granted, the NSIDC called the May numbers “tentative” because of problems with the satellites that scientists rely on to observe the Arctic, but added that they are “supported by other data sources.” Read More here
27 May 2016, The Conversation, Antarctica may not be as isolated as we thought, and that’s a worry. For a long time, we have thought of Antarctica as isolated from the rest of the world. The continent is entirely surrounded by the Southern Ocean, which heaves with giant waves whipped up by intense winds, and is home to the world’s strongest ocean current, the eastward-flowing Antarctic circumpolar current (ACC). The Southern Ocean is associated with several circumpolar oceanic fronts (see image below), where sharp transitions in ocean temperature and salinity occur. One of the most significant of these is the Antarctic polar front, a convergence zone where cold Antarctic water sinks under warmer sub-Antarctic water. Ocean barrier The polar front was considered as a barrier blocking movement of marine plants and animals into and out of Antarctica. Many groups of organisms show strong differences on either side of the front, suggesting northern and southern populations have been separated for a long time. We know from genetic work that some species, such as some molluscs and crustaceans, have managed to cross the front in the past, but there is little evidence that biological movement across the front can or does still occur. Read More here
23 May 2016, The Conversation, Coastal law shift from property rights to climate adaptation is a landmark reform. Coastal management in Australia is subject to competing interests and challenges. These range from land use and strategic planning issues to ecosystems preservation. Local councils are at the coalface as both key decision-makers and the first point of contact for communities. Exacerbating these day-to-day challenges for councils are risks to property. A quantitative assessment undertaken by the then-Department of Climate Change in 2009 identified impacts of sea-level rise as a serious threat to property. In New South Wales, under scenarios of a 1.1-metre sea-level rise, risks of damage or inundation to residential housing alone affected tens of thousands of properties, potentially costing millions of dollars. The NSW 2009 sea-level rise policy (now repealed) saw coastal councils considering this future risk when developing coastal zone management plans. These metrics, while important, say little of the wide-ranging benefits of a freely accessible coast. Going to the beach is a fundamental part of Australian identity; it’s a “special place” for Australians. Local councils are most exposed to the issues and challenges of a changing coastline in which there are many interests. Councils are often the first decision-makers for local development, asset management and land-use and strategic planning. Increased coastal erosion, storm events, more frequent and severe flooding impacts and higher tides can and will make these regular functions of councils more complicated. In this context, the tabling of the NSW Coastal Management Bill on May 3 marks the formalisation of Stage 2 of the most significant law reform to coastal management since the 1970s. The NSW state government saysthat, by better integrating coastal management with land-use planning, the legislation offers: … a modern, coherent coastal management framework that is responsive to current needs and future challenges. Read More here