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Category Archives: Impacts Observed & Projected

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13 November 2015, Climate News Network, Global warming drains the water of life. Melting snowpack in Turkey’s Lesser Caucasus mountains. New research warns that rising temperatures are reducing the mountain snow on which billions of people in lowland areas depend for their water supply. Up to two billion people who depend on winter snow to deliver their summer water could see shortages by 2060 as upland and mountain snowpacks continue to dwindle. An estimated 300 million people could find, 45 years on, that they simply won’t have enough water for all their needs, according to new research. Climate change driven by rising atmospheric levels of carbon dioxide – in turn, fed by human combustion of fossil fuels – may already be affecting global precipitation. Researchers have consistently found that much of the world’s drylands will increase as global average temperatures rise. But warmer temperatures increasingly also mean the water that once fell as snow, to be preserved until the summer, now falls as winter rain, and runs off directly. The snow that does fall is settling at ever higher altitudes and melting ever earlier. Reliable flow This is bad news for agricultural communities that depend on a reliable flow of meltwater every summer. California is already in the grip of a sustained drought, made worse by lower falls of snow. Great tracts of Asia depend on summer meltwater from the Himalayan massif and the Tibetan plateau. Justin Mankin, an environmental scientist at Columbia University’s Earth Institute in the US, and colleagues report in Environmental Research Letters journal that they studied 421 drainage basins across the northern hemisphere. Read More here

 

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10 November 2015, Science Daily, Geophysics could slow Antarctic ice retreat. Gravitational effects, variations in Earth structure could damp rise in global sea levels. The anticipated melting of the massive West Antarctic Ice Sheet could be slowed by two big factors that are largely overlooked in current computer models, according to a new study. The findings, published online in Nature Communications, suggest that the impact on global sea levels from the retreating ice sheet could be less drastic — or at least more gradual — than recent computer simulations have indicated. Over the past year, numerous studies have warned that parts of the West Antarctic Ice Sheet are on the verge of a runaway retreat. Just last week a high-profile research paper forecast that this could lead eventually to a rise in global sea levels of as much as three metres. The authors of the new Nature Communications paper, however, focus on two geophysical elements that they say aren’t adequately reflected in computer simulations for this region: the surprisingly powerful gravitational pull of the immense ice sheet on surrounding water, and the unusually fluid nature of the mantle beneath the bedrock that the ice sits on. “The fate of the polar ice sheets in a warming world is a major concern for policy makers — and attention is rightly focused on the importance of restraining CO2 emissions and preparing for rising sea levels,” says lead author Natalya Gomez, an assistant professor of Earth and Planetary Sciences at McGill University in Montreal. “But our study shows that for Antarctica, in particular, computer models also need to take into account how gravitational effects and variations in Earth structure could affect the pace of future ice-sheet loss.” Read More here

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10 November 2015, The Guardian, New insect arrivals signal radical climate change – we can’t say we’ve not been warned. The exotic species colonising the south coast are the experts when it comes to adapting and surviving. We should learn from them. Something stunning happened last week, which has never before occurred in Britain in November: a subtropical butterfly, the long-tailed blue, was seen flying on the south coast of England. Another unprecedented event took place one August evening: a volunteer at the Dungeness bird observatory was strolling home from the pub when he was transported to summer holidays on Mediterranean verandas – he heard the nocturnal whirring of tree crickets. Hundreds of these warmth-loving insects have now been found breeding in Britain for the first time. Exceptional insects are the new normal. The long-tailed blue is a common sight across Africa, south Asia and Australia. Very occasionally – in 1945 and again in 1990 – warm winds push a couple of dozen to Britain. In 2013, however, more than 100 individuals were spotted between Bognor and Dover. This year has seen another 60 mostly British-born specimens emerging spectacularly late in the year for any butterfly, let alone a subtropical creature. We struggle to act on climate change because it involves restraining consumption – of fossil fuel – and we as a species find it hard to practise restraint. We are also struggling because arguments focused on parts per million of CO2 are abstract and remote from real experience. Insects could help us realise just how radically our climate is changing. Forgive an obvious animal cliche, but they are the canary in the coal mine. Along with tree bumblebees, another very visible newcomer in Britain, we might describe them as the first climate refugees to reach our shores. Read More here

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10 November 2015, The Conversation, Ocean acidification: the forgotten piece of the carbon puzzle. Ocean acidification – the rise in ocean acidity due to the increased absorption of carbon dioxide (CO₂) – is often thought of as consequence of climate change. However, it is actually a separate, albeit very closely-related problem. Ocean acidification is often referred to as “the other CO₂ problem” because, like climate change, it is primarily a result of the increased emissions of this gas. Despite their common driver, though, the processes and impacts of ocean acidification and climate change are distinct. It should not be assumed that policies intended to deal with the climate will simultaneously benefit the oceans. The current emphasis of global climate policies on a warming target is a case in point. A narrow focus on temperature stabilisation, for example, opens the door for policy interventions that prioritise the reduction of greenhouse gases other than carbon dioxide. This is because non-CO₂ greenhouse gases — like methane and nitrous oxide, which can arise from agricultural and industrial processes — typically have a higher global warming potential and might even be less costly than CO₂ to reduce. In addition, several geoengineering schemes have been proposed to reduce the impacts of a warming climate. Yet such schemes often do nothing to address emissions, and may even exacerbate carbon absorption in the oceans. Read More here

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