Study Suggests Melting in Arctic Could Release Heat-trapping Gases
A new study suggests that increased warming in Arctic areas could release huge amounts of carbon into the atmosphere.
The study centered on the permafrost layer beneath Arctic soil. The researchers said melting of this layer could release billions of tons of carbon into the atmosphere, with big effects on worldwide temperatures.
Permafrost is a layer of soil in the world's Arctic and Antarctic areas. It has, in some cases, remained frozen for many years. Permafrost is important to the world's climate because it is believed to store two times the amount of carbon as there is in the atmosphere.
The study was published this month in the science journal Nature Geoscience. Researchers examined how the top layer of this frozen soil warms during the summer. That is when plants and microorganisms come to life. The microorganisms eat plant roots and "breathe" like all living organisms, releasing carbon dioxide which is considered a heat-trapping, greenhouse gas. Scientists call this process rhizosphere priming.
The researchers say as more frozen soil warms up, more plant roots are becoming exposed to microorganisms. As a result more carbon dioxide is being released. The researchers estimated the process could add as much as 40 billion tons of carbon to the atmosphere by the year 2100.
Until now, the United Nations Environment Programme had estimated that global emissions of carbon gases must fall by 7.6 percent every year for the next 10 years. That is what scientists say would be needed to prevent world temperatures from rising more than 1.5 degrees Celsius –the main temperature goal of the Paris Agreement.
But the writers of the new study note that their estimates are currently "unaccounted for" in global emission predictions. "To keep warming below 1.5 or 2 °C," the authors wrote, emissions "may need to be even more constrained."
Researchers suggest that warming in the Arctic is worse than in other places. Studies by the United States space agency and the U.S. National Oceanic and Atmospheric Administration suggest that the past 10 years have been the hottest on record. In the Arctic, air temperatures are rising two times as fast as the global average.
I'm John Russell.
北极永冻土解冻将释放大量碳
一项新的研究表明，北极地区变暖的加剧可能会向大气中释放大量的碳。
这项研究集中在北极土壤下面的永久冻土层上。研究人员表示，永冻土的融化可能会向大气中释放数十亿吨的碳，对全球气温产生重大影响。
永久冻土层是世界北极和南极地区的一层土壤。在某些情况下，它已经冻结了很多年。永冻土对世界气候至关重要，因为人们认为它储存的碳量是大气中的两倍。
这项研究发表在本月的科学杂志《自然地球科学》上。研究人员检查了这些冻土的表层在夏季是如何变暖的。此时的植物和微生物开始焕发生机。这些微生物以植物根系为食，像所有生物体一样“呼吸”，释放出二氧化碳，这被认为是一种吸热的温室气体。科学家称这个过程为“根际激发”。
研究人员说，随着越来越多的冻土层解冻，越来越多的植物根系接触到微生物。结果，更多的二氧化碳被释放出来。研究人员估计，到2100年，这一过程可能给大气增加多达400亿吨的碳。
到目前为止，联合国环境规划署估计，未来10年，全球碳排放必须每年下降7.6%。科学家们表示，这是防止全球气温上升超过1.5摄氏度所需要的目标。1.5摄氏度是《巴黎协定》设定的主要温控目标。
但这项新研究的作者指出，他们的估计目前在全球排放预测中“未被计入”。“要将升温控制在1.5或2摄氏度以下，”作者写道，碳排放“可能需要更加严格的限制。”
研究人员认为，北极的变暖比其他地方更严重。美国航天局和美国国家海洋和大气管理局的研究表明，过去10年是有记录以来最热的10年。在北极，气温上升的速度是全球平均水平的两倍。
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