24 November 2015, Climate News Network, Trees face global extinction threat. Field scientists warn that damage being done to the Amazon rainforest indicates that most of the world’s 40,000 tropical tree species now qualify as being at risk. More than half of all tree species in the Amazon forest could be at risk of extinction, according to new research. There are at least 15,000 species of tree in and around the Amazon basin and the Guiana Shield. At the lowest estimate, 36% are at risk, but the proportion under threat could also be as high as 57%. And since the Amazon rainforest is one of the planet’s richest habitats, and since what is true for one tropical great forest must apply to others, the research suggests that the number of threatened plant species on the planet could rise by 22%. Tropical trees worldwide number more than 40,000 species, and most of these may qualify as being to some degree threatened. Deforestation maps Hans ter Steege, research fellow at the Naturalis Biodiversity Centre in the Netherlands, and 157 colleagues from 21 countries report in Science Advances journal that they started with data from 1,485 forest inventories and measurements of species density from more than 1,600 plots of forest made across the Amazon region. They matched the information with maps of deforestation happening right now, or projected to happen, and then used statistical methods to make a range of estimates of the numbers of species at risk. The forests of the Amazon have already lost 12% of their original extent. By 2050, they could have lost at least another 9%, and perhaps as much as 28%. The forests are at risk from invasion by people hungry for land, and exploitation for mining and dam construction, as well as fire, drought and climate change. Read More here
Category Archives: Impacts Observed & Projected
23 November 2015, Reuters, Weather disasters occur almost daily, becoming more frequent -UN. Weather-related disasters such as floods and heatwaves have occurred almost daily in the past decade, almost twice as often as two decades ago, with Asia being the hardest hit region, a U.N. report said on Monday. While the report authors could not pin the increase wholly on climate change, they did say that the upward trend was likely to continue as extreme weather events increased. Since 1995, weather disasters have killed 606,000 people, left 4.1 billion injured, homeless or in need of aid, and accounted for 90 percent of all disasters, it said. A recent peak year was 2002, when drought in India hit 200 million and a sandstorm inChina affected 100 million. But the standout mega-disaster was Cyclone Nargis, which killed 138,000 in Myanmar in 2008. While geophysical causes such as earthquakes, volcanoes and tsunamis often grab the headlines, they only make up one in 10 of the disasters trawled from a database defined by the impact. The report, called “The Human Cost of Weather Related Disasters”, found there were an average of 335 weather-related disasters annually between 2005 and August this year, up 14 percent from 1995-2004 and almost twice as many as in the years from 1985 to 1994. “While scientists cannot calculate what percentage of this rise is due to climate change, predictions of more extreme weather in future almost certainly mean that we will witness a continued upward trend in weather-related disasters in the decades ahead,” the report said. Read More here
23 November 2015, Aljazeera, Siberia’s melting permafrost fuels climate change. Over the past year, a number of giant, mysterious holes have emerged in Siberia, some as deep as 200 metres. Scientists say the craters may be emerging because the frozen ground, or “permafrost”, that covers much of Siberia has been thawing due to climate change, allowing methane gases trapped underground to build up and explode. Permafrost is ground that is permanently frozen, where the ground temperature has remained below zero degrees Celsius for at least two years. It covers about a quarter of the northern hemisphere’s land surface. When permafrost thaws, microbes digest the plant and animal remains that were locked in the permafrost and release greenhouse gases, carbon dioxide and methane into the atmosphere. The phenomenon is a self-feeding cycle, explained Sarah Chadburn, from the University of Exeter. “Permafrost soils contain vast amounts of carbon, nearly twice as much as is currently in the atmosphere. As the permafrost thaws in a warming climate, the soil decomposes and releases carbon to the atmosphere as carbon dioxide and methane. These are greenhouse gases, and they warm the Earth even more. This leads to more permafrost thawing, more carbon release, and so the cycle continues,” Chadburn said. Read More here
18 November 2015, Science Daily, Sea level rise from Antarctic collapse may be slower than suggested. A new study by scientists in the UK and France has found that Antarctic ice sheet collapse will have serious consequences for sea level rise over the next two hundred years, though not as much as some have suggested. This study, published today in the journal Nature, uses an ice-sheet model to predict the consequences of unstable retreat of the ice, which recent studies suggest has begun in West Antarctica. Scientists, led by Catherine Ritz from Université Grenoble Alpes in France and Tamsin Edwards from The Open University, predict that the contribution is most likely to be 10 cm of sea-level rise this century under a mid to high climate scenario, but is extremely unlikely to be higher than 30 cm. When combined with other contributions, that’s a significant challenge for adapting to future sea level rise. But it’s also far lower than some previous estimates, which were as high as one metre from Antarctica alone. The study’s central estimate raises the Intergovernmental Panel on Climate Change (IPCC) central prediction of 60 cm global sea-level rise by just a few centimetres under the mid to high scenario they used. But the UK and France team’s method allowed them to assess the likelihood of sea-level rise from substantial parts of the ice sheet collapsing, which the IPCC could not due to a lack of evidence. They predict there is a one in twenty chance that Antarctic collapse could contribute more than 30 cm sea-level rise by the end of the century and more than 72 cm by 2200. This does not rule out larger contributions on longer time scales. Read More here