31 October 2016, The Conversation, Unnatural disasters: how we can spot climate’s role in specific extreme events. These days, after an extreme weather event like a cyclone, bushfire, or major storm, it’s common to find people asking: was it climate change? We also often hear people saying it is impossible to attribute any single weather event to climate change, as former prime minister Tony Abbott and the then environment minister Greg Hunt said after the bushfires in New South Wales in 2013. While this may have been true in the 1990s, the science of attributing individual extreme events to global warming has advanced significantly since then. It is now possible to link aspects of extreme events to climate change. However, as I describe in an article co-written by Susan Hassol, Simon Torok and Patrick Luganda and published today in the World Meteorologcal Organization’s Bulletin, how we communicate these findings has not kept pace with the rapidly evolving science. As a result, there is widespread confusion about the links between climate change and extreme weather. Evolving science The science of attributing individual extreme weather events to climate change dates back to 2003, when a discussion article in Nature raised the question of liability for damages from extreme events. The idea was that if you could attribute a specific event to rising greenhouse gas emissions, you could potentially hold someone to account. This was soon followed by a 2004 study of the 2003 European heatwave, which caused more than 35,000 deaths. This analysis found that climate change had more than doubled the risk of such extreme heat. Read More here
Category Archives: Impacts Observed & Projected
27 October 2016, Aust Antarctic Division, Impact of East Antarctic glacial melt on sea-level rise. The Australian Antarctic Program will study two glaciers, the Totten and Sørsdal, in East Antarctica this summer to better understand the impact ice melt is having on global sea-level rise. The Totten Glacier, near Australia’s Casey research station, is the largest glacier in East Antarctica, and is showing signs that it is sensitive to warm ocean waters that can increase melt at the base of the ice shelf. Australian Antarctic Division Glaciologist, Dr Ben Galton-Fenzi, said researchers want to better understand how much this glacial melt is driving sea-level rise. “Since the 1900s the global sea-level has risen by around 20 centimetres and by the end of the century it’s projected to rise by up to one metre or more, but this is subject to high uncertainty,” Dr Galton Fenzi said. “These estimates depend critically on understanding Antarctic glaciers, both how much and how fast they melt in a warming climate. This summer researchers will look at how warmer ocean water is melting glaciers and ice shelves from below. “We will land helicopters on the Totten to deploy six GPS units to measure glacial flow speeds and surface elevation changes. Read More here
24 October 2016, NASA, Studies offer new glimpse of melting under Antarctic glaciers. Two new studies by researchers at NASA and the University of California, Irvine (UCI), detect the fastest ongoing rates of glacier retreat ever observed in West Antarctica and offer an unprecedented direct view of intense ice melting from the floating undersides of glaciers. The results highlight how the interaction between ocean conditions and the bedrock beneath a glacier can influence the glacier’s evolution, with implications for understanding future ice loss from Antarctica and global sea level rise. The two studies examined three neighboring glaciers in West Antarctica that are melting and retreating at different rates. Smith, Pope and Kohler glaciers flow into the Dotson and Crosson ice shelves in the Amundsen Sea Embayment in West Antarctica, the part of the continent with the largest loss of ice mass. A study led by Bernd Scheuchl of UCI, published in the journal Geophysical Research Letters on Aug. 28, used radar measurements from the European Space Agency’s Sentinel-1 satellite and data from the earlier ERS-1 and ERS-2 satellites to look at changes in the glaciers’ grounding lines — the boundary where a glacier loses contact with bedrock and begins to float on the ocean. The grounding line is important because nearly all glacier melting takes place on the underside of the glacier’s floating portion, called the ice shelf. If a glacier loses mass from enhanced melting, it may start floating farther inland from its former grounding line, just as a boat stuck on a sandbar may be able to float again if a heavy cargo is removed. This is called grounding line retreat. Read More here
22 October 2016, Climate News Network, Bolivian glaciers melt at alarming rate. A new study mapping the effects of dwindling glaciers on people living in Bolivia reveals rapid shrinkage and potentially dangerous glacial lakes. Between 1986 and 2014 – one human generation –the glaciers of Bolivia shrank by 43%, according to new research. This presents a problem in the long term for more than 2 million people who rely on glacial meltwater supply in the dry season, and immediate danger in the short term for thousands who might live below precarious glacial lakes. Glaciers are in retreat as the world warms − a consequence of rising levels of carbon dioxide in the atmosphere in response to the increasing combustion of fossil fuels. They are dwindling almost everywhere in the Andean chain, in Greenland, in Alaska and Canada, the Himalayas, across the entire mass of Central Asia,and everywhere in the tropics. Tropical glaciers But a new study in The Cryosphere, the journal of the European Geosciences Union, is one of the first to examine in detail precisely what this retreat could mean for the human communities in Bolivia, home to one-fifth of the world’s tropical glaciers. Researchers from two British universities and a Bolivian colleague examined NASA satellite images of the region and found that the area of the Bolivia Cordillera Oriental normally covered by glaciers fell from 530 square kilometres in 1986 to about 300 sq km in 2014 − a shrinkage of more than two-fifths. Read more here