19 December 2016, Climate News Network, Growing tornado impact puzzles scientists. The US seems to be experiencing more and worse tornado outbreaks – groups of twisters in quick succession. But climate change may not be the culprit. Tornado outbreaks – those sudden, multiple whirlwinds that can randomly destroy whole townships or pass by and do little more than ruffle the prairie grass – may be getting more frequent and more powerful in the United States. And nobody can be sure why. Climate change driven by global warming which is in turn the consequence of greenhouse gas emissions from fossil fuel combustion could be a candidate cause. But meteorologists cannot rule out some other potential explanation, such as some natural cycle in climate behaviour involving oceans and atmosphere. But they do know that tornado outbreaks are becoming potentially more destructive. Two years ago, researchers checked the data and found that the tornado “season” in the US was now two weeks earlier than it had been in the early 20th century. In the spring of 2016 a team from Columbia University checked the records since 1954 and found that the number of individual tornadoes during any single episode of tornado outbreaks has been rising for the past six decades. Worse winds And now Michael Tippett, a physicist at Columbia Engineering, has returned to the challenge. He and two colleagues report in the journal Science that not only are the numbers of twisters in each outbreak growing, but the overall severity of the whirlwinds is on the increase. And the fastest increase is in the most extreme range of the phenomenon. Read More here
Category Archives: Impacts Observed & Projected
16 December 2016, Australian Antarctic Magazine › 2016-2020 › Issue 31, Low winter sea-ice coverage bucks trend. Winter sea-ice coverage around Antarctica was noticeably reduced in September this year, with sea ice extent starting its annual retreat early and setting new daily record lows. The result comes two years after winter sea ice extent around Antarctica reached a record high in September 2014, when it exceeded 20 million square kilometres for the first time since satellite measurements began in 1979. This year, Antarctic sea ice began its annual spring retreat roughly four weeks earlier than average, after peaking at 18.5 million square kilometres on 28 August 2016, which was close to the lowest winter maximum on record. Dr Jan Lieser from the Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC) and the Australian Research Council-funded Antarctic Gateway Partnership said it was a surprising finding, given the trend in recent years.“Within the space of just two years we have gone from a record high winter sea-ice extent to record daily lows for this point in the season. This is a great reminder that we are dealing with an extremely variable component of the climate system,” Dr Lieser said. “It’s also a reminder of why it can be unwise to leap to conclusions about the link between Antarctic sea ice and climate change on the basis of one or two years of data. It is the long-term trends that are most important, as well as the regional variability, which is high around Antarctica.” Read More here
16 December 2016, The Conversation, Climate change played a role in Australia’s hottest October and Tasmania’s big dry in 2015. Climate change made some of Australia’s 2015 extreme weather events more likely, according to research published today in the Bulletin of the American Meteorological Society. As part of an annual review of global weather extremes, these studies focused on October 2015, which was the hottest on record for that month across Australia. It was also the hottest by the biggest margin for any month. October 2015 was also the driest for that month on record in Tasmania, which contributed to the state’s dry spring and summer, and its bad fire season. El Niño events usually drive global temperatures higher, and 2015 had one of the strongest on record. So were these records due to El Niño, or climate change? The research shows that while El Niño had some influence on Australia’s weather, it was not the only culprit. El Niño packed a punch – or did it? In 2015, a strong El Niño developed, with record high temperatures in the central equatorial Pacific Ocean contributing to 2015 being the hottest year on record globally (although 2016 will smash it). The Indian Ocean was also very warm. El Niño is often associated with warm and dry conditions across eastern Australia, particularly in spring and summer. The new studies found that for Australia as a whole, while El Niño did make the continent warmer, its direct contribution to record temperatures was small. Only in the Murray Darling Basin did El Niño make it more likely that the October 2015 heat would be a record. El Niño also played a small but notable role in the dry October in Tasmania. Read More here
13 December 2016, Inside Climate News, ‘The Arctic Is Unraveling,’ Scientists Conclude After Latest Sobering Climate Report. The ill winds of climate change are irrevocably reshaping the Arctic, including massive declines in sea ice and snow and a record-late start to sea ice formation this fall. Those were the sobering conclusions of the 2016 Arctic Report Card released Tuesday. The report card is sponsored by the National Oceanic and Atmospheric Administration (NOAA) and co-authored by more than 50 scientists from Asia, North America and Europe. The data shows that the Arctic is warming at double the rate of the global average temperature. Between October 2015 and September 2016, temperatures over Arctic land areas were 2.0 degrees Celsius above the 1981-2010 baseline, the warmest on record going back to 1900. The report, released at the American Geophysical Union meeting in San Francisco, clearly links the Arctic heatwave to a record-late start to formation of sea ice this fall, and to record high and low seasonal snow cover extent in the Northern Hemisphere. If the extreme warmth recorded in the Arctic this fall persists for the next few years, it may signal a completely new climate in the region, scientists said. Jeremy Mathis, director of NOAA’s Arctic Research Program, said the report highlights the clear and pronounced global warming signal in the Arctic and its effects cascading throughout the environment, like the spread of parasitic diseases in Arctic animals. “We’ve seen a year in 2016 like we’ve never seen before … with clear acceleration of many global warming signals. The Arctic was whispering change. Now it’s not whispering. It’s speaking, it’s shouting change, and the changes are large,” said co-author Donald Perovich, who studies Arctic climate at Dartmouth College. Sustained observations of the Arctic is crucial to making science-based policy decisions, he added, a goal threatened by the inclusion of numerous climate deniers in President-elect Donald Trump’s cabinet. This week, Trump’s transition team posted a new “Energy Independence” website that repeats his previous intentions to open up vast areas for fossil fuel development and to scrap existing climate action plans. Arctic ice doesn’t care about politics, and what happens in the region now is critically important to the U.S., said Rafe Pomerance, chair of Arctic 21 and a member of the Polar Research Board of the National Academies of Sciences, Engineering and Medicine. Read More here