[ti:Arctic Ocean Ice Shrinks to Second Lowest Level on Record] [by:www.51voa.com] [00:00.00]更多听力请访问51VOA.COM [00:00.04]Scientists say ice in the Arctic Ocean [00:04.00]melted to its second lowest level on record this summer. [00:11.40]Arctic sea ice melts over the summer, [00:15.52]reaching its lowest point sometime during September. [00:21.40]Then, during the winter, ice builds up again [00:25.56]and reaches its highest level in March. [00:30.64]The National Snow and Ice Data Center [00:34.52]at the University of Colorado Boulder [00:38.08]uses satellite imagery to observe and measure the ice levels. [00:45.88]The center recently announced its latest findings [00:50.20]about sea ice levels at the North Pole, as well as areas off Canada, [00:56.84]Greenland, Russia and the U.S. state of Alaska. [01:03.12]Researchers reported Arctic Ocean ice levels reached a summertime low [01:10.00]of 3.7 million square kilometers on September 15. [01:18.00]That is the second lowest level recorded since 1979, [01:24.32]when satellite observations of the sea ice began. [01:29.36]The lowest level recorded was in 2012, [01:33.76]when the ice shrank to 3.4 million square kilometers. [01:39.84]In the 1980s, the ice cover was about [01:43.96]2.7 million square kilometers bigger than current summer levels. [01:51.56]Mark Serreze is director of the National Snow and Ice Data Center. [01:58.36]"It's been a crazy year up north, with sea ice at a near-record low," [02:04.60]he told the French news agency AFP. [02:09.24]He noted the heat waves and massive forest fires [02:13.56]in the Siberian area of Russia. [02:17.40]He said the heat wave last spring and natural climate conditions [02:23.28]in the Arctic played a part in the latest sea ice melt. [02:29.56]He noted that temperatures for much of the year in the Siberian Arctic [02:35.24]were 8 to 10 degrees Celsius above normal. [02:40.80]Some of the warming was caused by the burning of coal, [02:45.72]oil and natural gas, he added. [02:50.56]"Absolutely we're seeing climate change at work [02:54.28]because the warm summers become warmer and the cold winters [02:59.72]aren't as cold as they were," Serreze said. [03:04.96]Melting sea ice does not directly add to rising sea levels. [03:10.88]But scientists say it can have a direct effect on rising temperatures. [03:18.08]"When the sea ice disappears, the incident sunlight gets absorbed in the ocean, [03:25.44]helping to further warm the Earth," Claire Parkinson told AFP. [03:32.88]She is a climate scientist with the U.S. space agency NASA. [03:39.44]Parkinson added that the lower ice coverage this year [03:44.40]was "in line with the overall downward" patterns of the past 40 years. [03:51.88]"What we are seeing here in the Arctic [03:54.96]is really the opening up of a new ocean on top of the world, [04:00.44]which means that we need to be protecting the area," she added. [04:06.96]In another recent study, U.S. researchers suggested [04:11.92]the Arctic has experienced such intense warming in recent decades [04:18.00]that it is now changing to a completely "new climate state." [04:24.64]The study was carried out [04:26.80]by the U.S. National Center for Atmospheric Research (NCAR). [04:32.20]The researchers said Arctic sea ice has seen such major melting [04:38.16]in recent decades that even an unusually cold year [04:43.04]"will no longer have the amount of summer sea ice [04:47.32]that existed as recently as the mid-20th century." [04:53.36]The study predicted that autumn and winter temperatures [04:57.92]will also warm enough to enter [05:01.28]a "statistically distinct climate" by the middle of this century. [05:07.28]This will likely result in seasonal changes [05:11.20]to include months when rain will fall instead of snow. [05:16.96]The scientists based their research on hundreds of detailed computer models [05:23.32]and observations of Arctic climate conditions. [05:28.92]They used this data to define climate conditions [05:33.20]of what they considered the "old Arctic." [05:38.00]The team then attempted to identify future climate changes [05:43.28]linked to human-caused warming. [05:47.12]The study was based on high-end predictions [05:50.68]for future levels of greenhouse gases, [05:54.68]pollutants that trap heat in Earth's atmosphere. [06:00.24]The researchers noted that lower greenhouse gas levels [06:05.24]would lessen future climate changes in the Arctic. [06:10.48]I'm Bryan Lynn. 更多听力请访问51VOA.COM