[ti:Study Suggests Melting in Arctic Could Release Heat-trapping Gases] [by:www.51voa.com] [00:00.00]更多听力请访问51VOA.COM [00:00.04]A new study suggests that increased warming in Arctic areas [00:06.92]could release huge amounts of carbon into the atmosphere. [00:12.20]The study centered on the permafrost layer beneath Arctic soil. [00:18.00]The researchers said melting of this layer [00:21.80]could release billions of tons of carbon into the atmosphere, [00:27.00]with big effects on worldwide temperatures. [00:31.04]Permafrost is a layer of soil in the world's Arctic and Antarctic areas. [00:37.96]It has, in some cases, remained frozen for many years. [00:43.64]Permafrost is important to the world's climate because it is believed [00:49.24]to store two times the amount of carbon as there is in the atmosphere. [00:56.20]The study was published this month in the science journal Nature Geoscience. [01:03.04]Researchers examined how the top layer of this frozen soil warms during the summer. [01:11.36]That is when plants and microorganisms come to life. [01:16.80]The microorganisms eat plant roots and "breathe" like all living organisms, [01:24.08]releasing carbon dioxide which is considered a heat-trapping, greenhouse gas. [01:30.76]Scientists call this process rhizosphere priming. [01:35.96]The researchers say as more frozen soil warms up, [01:40.52]more plant roots are becoming exposed to microorganisms. [01:45.96]As a result more carbon dioxide is being released. [01:52.08]The researchers estimated the process could add as much [01:56.40]as 40 billion tons of carbon to the atmosphere by the year 2100. [02:03.12]Until now, the United Nations Environment Programme [02:08.40]had estimated that global emissions of carbon gases [02:12.52]must fall by 7.6 percent every year for the next 10 years. [02:20.68]That is what scientists say would be needed to prevent world temperatures [02:26.72]from rising more than 1.5 degrees Celsius [02:31.76]–the main temperature goal of the Paris Agreement. [02:36.44]But the writers of the new study note that their estimates [02:40.96]are currently "unaccounted for" in global emission predictions. [02:46.84]"To keep warming below 1.5 or 2 °C," the authors wrote, [02:53.72]emissions "may need to be even more constrained." [02:58.16]Researchers suggest that warming in the Arctic is worse than in other places. [03:05.24]Studies by the United States space agency [03:09.16]and the U.S. National Oceanic and Atmospheric Administration [03:14.40]suggest that the past 10 years have been the hottest on record. [03:20.24]In the Arctic, air temperatures are rising two times as fast as the global average. [03:28.64]I'm John Russell. 更多听力请访问51VOA.COM