Category Archives: Impacts Observed & Projected

PLEA Network

5 June 2016, Climate News Network, Europe’s floods come as no surprise. Scientists have warned that the extra moisture in warmer air will mean more intense rainfall, but floods still leave governments unprepared. At least 18 people have lost their lives in central Europe as severe floods engulf the continent from France to Ukraine. In Paris the River Seine reached 6.1 metres (20 feet) above normal, and tens of thousands of people have fled their homes. If the downpours and swollen rivers came as a surprise, they shouldn’t have done. Not only are there historical precedents for disastrous floods. There have beengraphic recent warnings too, spelling out the growing likelihood that the warming climate will make bouts of flooding and other extreme weather more frequent. Last March a study reported in the journal Nature said climate change was already driving an increase in extremes of rainfall and snowfall across most of the globe, even in arid regions. The study said the trend would continue as the world warmed. The role of global warming in unusually large rainfall events in countries from the United Kingdom to China has been hotly debated. But this latest study showed that climate change is driving an overall increase in rainfall extremes. Its lead author, Markus Donat, a climate scientist at the University of New South Wales in Australia, said: “In both wet and dry regions, we see these significant and robust increases in heavy precipitation.” “It is probably a good idea to invest in infrastructure that helps in dealing with heavier precipitation” Warm air holds more moisture, and global warming is already increasing the odds of extreme rainfall. “The paper is convincing and provides some useful insights,” said Sonia Seneviratne, a climate scientist at the Swiss Federal Institute of Technology. “What is particularly new in this article is the demonstration of such a signal for observed changes in dry regions.” Read More here

 

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5 June 2016, The Conversation, A hard rain’s gonna fall: deep water for the election campaign. With an unprecedented storm flooding large population centres on Australia’s east coast over the weekend, you would be forgiven for thinking politicians on the campaign trail might pause to reflect on climate change. On the other side of the world, France and much of west and northern Europe are also experiencing extensive floods. They are unprecedented in the speed at which they have deluged cities and communities. Climate change did not over determine these floods in Australia and Europe. But, it has super-charged their intensity and speed in a way that would make them rare in the past. The weather patterns are complex, but the climate change part of the science is less so. Every 1℃ increase in global average temperature means the atmosphere can hold 7% more water vapour. This means that when moist air condenses into rainfall, it is capable of coming down for much longer and in much greater volume than it did in pre-industrial times. Climate change is not about some kind of linear increase in temperature. It is about an increase in energy in the climate system that produces extremes – in drought, storms, wind, heatwaves and floods. Floods are just one of the expressions of the violence of the excess energy. Analysis from the Potsdam Institute for Climate Impact Research, published last year and reported in the New York Times, showed record-breaking rainfall has increased 12% from 1980 to 2010 compared to the previous 80 years. In Europe, the increase was 31%. This is because the northern hemisphere temperature anomalies are so much greater than the south.Read More here

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4 June 2016, Climate News Network, Warming turns northern tundra green. Rising temperatures are creating longer Arctic growing seasons and increasing the risk of carbon escaping into the atmosphere from the thawing permafrost.  The northern edge of North America is getting steadily greener. In the most detailed study so far of plant growth across Alaska and Canada, scientists say that about a third of the land cover now looks less like tundra, and more like a warmer ecosystem. The researchers report in the Journal of Remote Sensing that examination of 87,000 images captured by the NASA Landsat satellite reveals that Alaska, Quebec and other regions became greener between 1984 and 2012. Landsat, a project also backed by the US Geological Survey (USGS), provides the longest space-based record of land vegetation in existence. Growing in size “The greening trend was unmistakable,” the scientists report. In Canada, northern forests tended to become greener, although if anything they declined in Alaska. Overall, 29.4% of the region became greener, and only 2.9% declined. The Arctic is the fastest-warming region of the northern hemisphere, with longer growing seasons and thawing permafrost. The scientists saw grassy tundra convert to shrubland, and shrubs grow in size and density, and such changes will inevitably start to play into water, energy and carbon cycles. Read More here

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2 June 2016, The guardian, Spike in Alaska wildfires is worsening global warming, US says Report from US Geological Survey says northern wildfires must now be seen as significant driver of climate change, not just a side-effect. The devastating rise in Alaska’s wildfires is making global warming even worse than scientists expected, US government researchers said on Wednesday. The sharp spike in Alaska’s wildfires, where more than 5 million acres burned last year, are destroying a main buffer against climate change: the carbon-rich boreal forests, tundra and permafrost that have served as an enormous carbon sink. Northern wildfires must now be recognised as a significant driver of climate change – and not just a side-effect, according to the report from the US Geological Survey. “This is one of the surprises that we haven’t talked about much,” said Virginia Burkett, chief climate scientist at the USGS. “It has tremendous implications for the carbon that is locked up in Alaska soils and vegetation.” A record wildfire year – such as 2015 which was the worst in Alaska for a decade – had a measurable effect on the release of carbon dioxide and methane, which are the main drivers of climate change. “Our scientists found that the balance of carbon storage versus release in Alaska was strongly linked with wildfires,” Burkett said. “In years where there was high wildfire activity the net carbon balance declined dramatically, and then it would rebuild in the absence of fire.” Alaska is a far bigger storehouse for carbon than the lower 48 states, according to the USGS. The state’s boreal forests, peat-rich tundra, and permafrost hold about 53% of US carbon. Alaska accounts for about 18% of US land mass. Alaska currently absorbs about 3.7m tonnes of carbon a year, the USGS assessment found. But that vast storehouse of carbon has been breached by warming temperatures, thawing permafrost – and wildfire. Read More here