Changes in the Arctic Ocean Carbon Cycle With Diminishing Ice Cover
Changes in the Arctic Ocean Carbon Cycle With Diminishing Ice Cover
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DOI：
10.1029/2020gl088051
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发表时间：
2020-06-28
影响因子：
5.2
通讯作者：
Steele, Michael
中科院分区：
文献类型：
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作者：
DeGrandpre, Michael;Evans, Wiley;Steele, Michael
不到三十年前，北冰洋（AO）只有一小部分没有冰，而且持续时间很短。与常年暴露在不断增加的大气水平的其他海洋盆地相比，冰盖使海面 pCO(2) 水平保持在较低水平。在本研究中，我们评估了 6 年期间沿加拿大盆地固定巡航航线收集的海面 pCO(2) 测量值。测量结果表明，在低冰年期间，平均 pCO(2) 水平显着升高。 pCO(2) 的增加可能是由海洋表面加热和大气中二氧化碳的吸收驱动的，这些过程的贡献存在较大的年际变化。这些发现表明，无冰期的增加将进一步增加海面 pCO(2)，从而降低加拿大盆地目前作为大气 CO2 净汇的作用。 通俗语言摘要 北冰洋 (AO) 冰盖正在减少，使海面暴露出来与大气中的气体进行交换。因此，大气中积累的人为二氧化碳现在可以更容易地进入AO。预计这将导致 AO 中的二氧化碳含量增加，但由于该地区缺乏数据，尚未建立明确的关系。我们在 2012 年至 2017 年的五次航行中测量了 AO 加拿大盆地的二氧化碳分压 (pCO(2))。这些数据表明，在冰浓度较低的年份，pCO(2) 较高，支持了之前的假设。我们通过模型证明，虽然大气中 CO2 的吸收增加了 pCO(2)，但加热也很重要。这些过程每年都有很大差异，掩盖了 pCO(2) 随着时间的推移可能增加的情况。根据这些结果，我们可以预计，虽然加拿大盆地一直是大气二氧化碳的汇，但未来几年大气二氧化碳的吸收量将会减少。
Less than three decades ago only a small fraction of the Arctic Ocean (AO) was ice free and then only for short periods. The ice cover kept sea surface pCO(2) at levels lower relative to other ocean basins that have been exposed year round to ever increasing atmospheric levels. In this study, we evaluate sea surface pCO(2) measurements collected over a 6-year period along a fixed cruise track in the Canada Basin. The measurements show that mean pCO(2) levels are significantly higher during low ice years. The pCO(2) increase is likely driven by ocean surface heating and uptake of atmospheric CO2 with large interannual variability in the contributions of these processes. These findings suggest that increased ice-free periods will further increase sea surface pCO(2), reducing the Canada Basin's current role as a net sink of atmospheric CO2.Plain Language Summary The Arctic Ocean (AO) ice cover is decreasing, exposing the sea surface to exchange with the gases in the atmosphere. Consequently, anthropogenic CO2 that has accumulated in the atmosphere can now more readily enter the AO. It is expected that this will lead to an increase in CO2 in the AO but because of a lack of data in the region, a clear relationship has not been established. We have measured the partial pressure of CO2 (pCO(2)) in the Canada Basin of the AO during five cruises spanning 2012-2017. These data have revealed that the pCO(2) is higher during years when ice concentration is low, supporting the previous hypothesis. Using a model, we have shown that while uptake of atmospheric CO2 has increased pCO(2), heating has also been important. These processes vary significantly from year to year, masking the likely increase in pCO(2) over time. Based on these results, we can expect that while the Canada Basin has been a sink for atmospheric CO2, the uptake of atmospheric CO2 will diminish in the coming years.