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2019-05-01. Burning Fossil Fuels Worsens Drought.

posted May 12, 2019, 7:35 AM by Alan Gould
By Jenessa Duncombe, Eos/AGU. [https://eos.org/articles/burning-fossil-fuels-worsens-drought] For GSS Climate Change chapter 8. Excerpt: Tree rings help scientists trace the influence of greenhouse gas emissions on 20th-century drought conditions. California’s governor declared the end of the state’s 5-year drought emergency in April 2017, and the dry spell that at times covered more than half the state left many wondering whether climate change was to blame. But scientists looking to answer that question often face a troubling conundrum: The earliest measurements of drought conditions were taken long after climate change had already begun reshaping the landscape. “In order to know if something is unusual [in the present day], you generally have to rely on climate models to estimate preindustrial variability,” said climate scientist Kate Marvel at NASA and Columbia University. “I was interested in finding a way around that.” A study released 1 May in the journal Nature uses historical tree ring data to track the influence of fossil fuel emissions on drought conditions around the globe over the past century. According to the new research, fossil fuel emissions had a detectable effect on the global hydroclimate as early as 1900, forcing some areas to grow drier and others to grow wetter over time. The study is the first to test the variations of global droughts in the past and attribute them to human actions....