Carbon dioxide sources from Alaska driven by increasing early winter respiration from Arctic tundra
Carbon dioxide sources from Alaska driven by increasing early winter respiration from Arctic tundra
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DOI：
10.1073/pnas.1618567114
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发表时间：
2017-05-23
影响因子：
11.1
通讯作者：
Wofsy, Steven C.
中科院分区：
文献类型：
--
作者：
Commane, Roisin;Lindaas, Jakob;Wofsy, Steven C.
高纬度生态系统有能力向大气释放大量二氧化碳（CO2），以应对不断升高的温度，这代表了气候系统内潜在的重要正反馈。在这里，我们将飞机和塔台对大气CO2的观测与遥感数据和气象产品相结合，得出了2012-2014年阿拉斯加全年的时间和空间分辨率的CO2通量。我们发现苔原生态系统每年都是大气中二氧化碳的净来源，在初冬（10月至12月）的呼吸速率特别高。巴罗的长期记录表明，自1975年以来，北坡冻土带的二氧化碳排放率在10月至12月期间增加了73% +/- 11%，这与夏季气温上升有关。综上所述，这些结果意味着阿拉斯加的早冬呼吸和年二氧化碳净排放量增加，以应对气候变暖。我们的研究结果提供了证据，表明CO2季节周期振幅的年代际增加可能与北极生物源排放的增加有关，在生长季节之后。在最近的气候评估中，用于预测未来碳通量的地球系统模式没有很好地模拟初冬呼吸。因此，这些评估可能低估了北极土壤因气候变暖而释放的碳。
High-latitude ecosystems have the capacity to release large amounts of carbon dioxide (CO2) to the atmosphere in response to increasing temperatures, representing a potentially significant positive feedback within the climate system. Here, we combine aircraft and tower observations of atmospheric CO2 with remote sensing data and meteorological products to derive temporally and spatially resolved year-round CO2 fluxes across Alaska during 2012-2014. We find that tundra ecosystems were a net source of CO2 to the atmosphere annually, with especially high rates of respiration during early winter (October through December). Long-term records at Barrow, AK, suggest that CO2 emission rates from North Slope tundra have increased during the October through December period by 73% +/- 11% since 1975, and are correlated with rising summer temperatures. Together, these results imply increasing early winter respiration and net annual emission of CO2 in Alaska, in response to climate warming. Our results provide evidence that the decadalscale increase in the amplitude of the CO2 seasonal cycle may be linked with increasing biogenic emissions in the Arctic, following the growing season. Early winter respirationwas not well simulated by the Earth System Models used to forecast future carbon fluxes in recent climate assessments. Therefore, these assessments may underestimate the carbon release from Arctic soils in response to a warming climate.