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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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9 November 2015, Science News, The past shows how abrupt climate shifts affect Earth. New research shows how past abrupt climatic changes in the North Atlantic propagated globally. The study, led by researchers from Centre for Ice and Climate at the University of Copenhagen’s Niels Bohr Institute, shows how interaction between heat transport in the ocean and the atmosphere caused the climatic changes to be expressed in different ways across the Southern Hemisphere. The results shows how forcing the climate system into a different state can trigger climate variations that spread globally and have very different impacts in different regions of Earth. This is important now, where rising atmospheric CO2 levels lead to global warming and may trigger abrupt climatic changes. The results have been published in the scientific journal Nature Geoscience. The history of climate on Earth is stored in tiny variations in kilometer-thick ice cores, sediments from lakes and oceans, and other natural archives that are layered down over thousands of years and works as archives of past temperatures. By recovering and deciphering these archives, researchers can reveal how and why the climate changed in the past, and in this way learn how the climate system may react in the future as the planet warms and the ice sheets melt. Read more here

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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

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24 August 2015, Climate Code Red, As 2015 smashes temperature records, it’s hotter than you think. There is an El Nino in full swing which helps push average global temperatures higher, and records are being broken, but just how hot is it? For several years, we have heard that global warming has pushed temperatures higher by around 0.8 to 0.85 degrees Celsius (°C). But in 2015, that number is not even close. Even before this year’s strong El Nino developed, 2015 was a hot year. The first few months of the year broken records for the hottest corresponding period in previous years all the way back to the start of the instrumental record in 1880. Each month, new records fell. 

With the July data in, the US Government’s National Oceanic and Atmospheric Administration reported that July was the hottest month among the 1627 months on record since 1880, and the first seven months of the year was the hottest January-July on record: The July average temperature across global land and ocean surfaces was 0.81°C above the 20th century average. As July is climatologically the warmest month for the year, this was also the all-time highest monthly temperature in the 1880-2015 record, at 16.61°C, surpassing the previous record set in 1998 by 0.08°C. The July globally-averaged sea surface temperature was 0.75°C above the 20th century average. This was the highest temperature for any month in the 1880-2015 record, surpassing the previous record set in July 2014 by 0.07°C. The global value was driven by record warmth across large expanses of the Pacific and Indian Oceans. The year-to-date temperature combined across global land and ocean surfaces was 0.85°C above the 20th century average. This was the highest for January-July in the 1880-2015 record, surpassing the previous record set in 2010 by 0.09°C. As 2015 smashes temperature records, it’s hotter than you think. Read More here

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