Forced Changes in the Arctic Freshwater Budget Emerge in the Early 21st Century
Forced Changes in the Arctic Freshwater Budget Emerge in the Early 21st Century
复制标题
DOI：
10.1029/2020gl088854
复制
发表时间：
2020-08-16
影响因子：
5.2
通讯作者：
Laiho, Rory
中科院分区：
文献类型：
--
作者：
Jahn, Alexandra;Laiho, Rory
北极液态淡水储量在过去几十年中显示出大幅增长，这提出了一个问题：北极液态淡水预算是否已经显示出明显的人为气候变化迹象，或者所观察到的变化是数十年变化的结果？我们表明，观测到的北极液态和固态FW储存的变化很可能已经受到气候变化的驱动，这是基于最先进的气候模式的总体模拟。一般来说，海洋通量比大气或陆地通量出现强迫变化的时间更早。Nares海峡液态FW通量是第一个在背景变化范围之外显示出现的通量，这种变化可能已经发生。其他净资产流入可能已开始转变，但尚未形成一个完全不同的机制。未来的减排有可能避免在背景变化之外出现一些净水通量。平白的语言摘要由于大量河流径流的输入，北冰洋的表层水比世界其他海洋更新鲜。非常新鲜的表层海洋不仅影响北冰洋的海洋环流和气候，而且还影响较低纬度的海洋环流和气候，特别是北大西洋。在过去的二十年里，由于目前尚不清楚的原因，北冰洋表层出现了清新现象。我们在这里证明，这种清新很可能已经受到气候变化的推动。此外，我们发现，由于人为气候变化，流入北大西洋的北极淡水通量也可能很快开始显示出变化的迹象，超出了我们过去观察到的变化范围。这里提供的有关气候变化信号出现的预期时间的信息将使我们能够实时监测即将发生的变化，以更好地了解北冰洋的变化如何影响全球气候。
Arctic liquid freshwater (FW) storage has shown a large increase over the past decades, posing the question: Is the Arctic FW budget already showing clear signs of anthropogenic climate change, or are the observed changes the result of multidecadal variability? We show that the observed change in liquid and solid Arctic FW storage is likely already driven by the changing climate, based on ensemble simulations from a state-of-the-art climate model. Generally, the emergence of forced changes in Arctic FW fluxes occurs earlier for oceanic fluxes than for atmospheric or land fluxes. Nares Strait liquid FW flux is the first flux to show emergence outside the range of background variability, with this change potentially already occurring. Other FW fluxes have likely started to shift but have not yet emerged into a completely different regime. Future emissions reductions have the potential to avoid the emergence of some FW fluxes beyond the background variability.Plain Language Summary The surface waters of the Arctic Ocean are fresher than the rest of the world oceans, due to the input of large amounts of river runoff. The very fresh surface ocean affects the ocean circulation and climate not just in the Arctic Ocean but also at lower latitudes, especially in the North Atlantic. The last two decades have seen a freshening of the surface Arctic Ocean, for reasons that are currently unknown. Here we demonstrate that this freshening is likely already driven by climate change. Furthermore, we find that due to manmade climate change, Arctic freshwater fluxes to the North Atlantic are also likely to soon start showing signs of change beyond the range of the variability we have observed in the past. The information provided here about the expected timing of the emergence of climate change signals will allow us to monitor upcoming changes in real time, to better understand how changes in the Arctic Ocean can impact climate worldwide.