Category Archives: Impacts Observed & Projected

PLEA Network

22 October 2015, The Guardian. Perth’s double whammy: as sea levels rise the city itself is sinking. The city’s growing population means a growing demand for water, but as more and more water is drawn out of Perth’s acquifers, the land is slowly subsiding. Growing demand for water in Perth has caused the city to sink at up to 6mm a year and could be responsible for an apparent acceleration in the rate of sea level rise, according to new research released by Curtin University. The study, published in the Journal of Geophysical Research in October, found that the rate of subsidence in Perth increased between 2000 and 2005, at the same time as the Water Corporation of WA increased the amount of water it was drawing from the city’s two main aquifers to meet the demands of a growing population. Will Featherstone, professor of geodesy at Curtin and the lead author of the study, described the effect as “like slowly letting the air out of a balloon”. “If you take the water out of the ground, the overburden of all the rocks above pushes down,” he told Guardian Australia. The city appears to be sinking at a rate of between 2mm and 6mm a year, variable throughout the Perth basin. The greatest change was measured at the seaside suburb of Hillarys, which has a GPS sensor to measure the rate of subsidence and a tidal marker operating side by side. Data for much of the Perth basin is patchy. A sinking city also has ramifications for the measurement of sea levels. A few years ago the rate of sea level rise in Western Australia was reported – not entirely accurately, it turned out – to be three times greater than the global average. Read More here

 

PLEA Network

22 October 2015, Climate News Network, Hurricanes’ economic havoc as world warms. Analysis of insurance data convinces environmental economists that climate change is pushing up the cost of dealing with the disastrous effects of extreme weather events. Climate change could already be costing the US billions of dollars each year in hurricane damage alone. Economists from Mexico and Europe believe that somewhere between $2bn and $14bn of the financial costs of hurricane damage in 2005 could be attributed to the impact of global warming. This is a bold statement. But Francisco Estrada, an environmental economics researcher at  the National Autonomous University of Mexico, and European colleagues report in Nature Geoscience that they have looked at the pattern of economic losses from hurricanes that matches a rise between 1990 and 2005 in the number and intensity of tropical cyclones. They say that this upward trend in loss “cannot be explained by commonly-used socioeconomic variables”. The distinction is an important one. Economic damage from climate-related events − ice storms, drought, flood, windstorms and heatwaves – has been on the increase for decades, but one explanation for this is population growth and economic development, even in the poorest regions. Read more here

PLEA Network

18 October 2015, Climate News Network, Climate changes can kick in below 2°C limit. Sudden shifts in settled climates can occur long before global warming reaches the internationally-agreed safety level, European scientists say. Climate change could arrive with startling speed. New research has identified at least 37 “tipping points” that would serve as evidence that climate change has happened – and happened abruptly in one particular region. And 18 of them could happen even before the world warms by an average of 2°C,  the proposed “safe limit” for global warming. Weather is what happens, climate is what people grow to expect from the weather. So climate change, driven by global warming as a consequence of rising carbon dioxide levels, in response to more than a century of fossil fuel combustion, could be – for many people – gradual, imperceptible and difficult to identify immediately. But Sybren Drijfhout, of the University of Southampton in the UK and his collaborators in France, the Netherlands and Germany, are not so sure. They report in the Proceedings of the National Academy of Sciences that they “screened” the massive ensemble of climate models that inform the most recent reports from the Intergovernmental Panel on Climate Change, and found evidence of abrupt regional changes in the ocean, the sea ice, the snow cover, the permafrost and in the terrestrial biosphere that could happen as average global temperatures reached a certain level. The models did not all simulate the same outcomes, but most of them did predict one or more abrupt regional shifts. No safe limit. But the future is not an exact science. “Our results show that the different state-of-the-art models agree that abrupt changes are likely, but that predicting when and where they will occur remains very difficult,” said Professor Drijfhout. “Also, our results show that no safe limit exists and that many abrupt shifts already occur for global warming levels much lower than two degrees.” The idea of a “tipping point” for climate change has been around for decades: the hypothesis is that a climate regime endures – perhaps with an increasing frequency of heat waves or windstorms or floods – as the average temperatures rise. However, at some point, there must be a dramatic shift to a new set of norms.Read More here

PLEA Network

15 October 2015, The Conversation, Death of a landscape: why have thousands of trees dropped dead in New South Wales? Trees die – that’s a fact of life. But is the death of an entire iconic landscape of Eucalyptus in the Cooma-Monaro region of New South Wales natural? For over a decade, large stands of Eucalyptus viminalis, commonly known as Ribbon Gum or Manna Gum, have been gradually declining in health, and now stand like skeletons in huge tree graveyards. In our recently published survey we found the affected area to cover almost 2,000 square km, about the size of the area burnt in the devastating Ash Wednesday bushfires in Victoria or more than the area covered by the 2003 Canberra fires. Within this area, almost every Ribbon Gum is either dead or showing signs of severe stress and dieback, with thinning crowns full of dead branches. Other tree species seem to be surviving, but this smooth-barked gum with its characteristic ribbons of peeling park, once the dominant tree of the Monaro, now seems set to disappear from the landscape. Read More here