The impacts of recent permafrost thaw on land-atmosphere greenhouse gas exchange
The impacts of recent permafrost thaw on land-atmosphere greenhouse gas exchange
复制标题
DOI：
10.1088/1748-9326/9/4/045005
复制
发表时间：
2014-04-01
影响因子：
6.7
通讯作者：
Wullschleger, Stan D.
中科院分区：
文献类型：
--
作者：
Hayes, Daniel J.;Kicklighter, David W.;Wullschleger, Stan D.
多年冻土融化和随后的活动的碳（C）储存在以前冻结的土壤有机质（SOM）有可能是一个强大的正反馈气候。由于北方永久冻土区的变暖速度比地球其他地区快一倍，永久冻土中大量的C很容易融化、分解并作为大气温室气体释放。高纬度陆地碳通量的诊断和预测估计在不同的模型之间差异很大，这取决于如何在永冻土动态，以及季节性解冻的“活跃层”上面，代表。在这里，我们采用了一个基于过程的模型模拟实验，以评估近几十年来，从1970年到2006年，在连续和不连续的永久冻土环极域的活动层动态对这种“永久冻土碳反馈”的净效应。在这段时间内，该模型估计平均增加6.8厘米的活性层厚度在整个域，这暴露了总共11.6 Pg C的解冻SOM分解。根据我们的模拟实验，动员这个以前冻结的C结果估计自1970年以来，直接与活跃层动态的累积净源3.7 Pg C的大气。从新暴露的有机质分解增强帐户释放的CO2（4.0 Pg C）和CH4（0.03 Pg C），但部分补偿CO2吸收（0.3 Pg C）与增强植被净初级生产力。这一估计的从永久冻土融化到大气中的净碳转移是泛北极整体生态系统碳预算的一个重要因素，也是八个北极国家在这段时间内化石燃料排放总量的重要贡献。
Permafrost thaw and the subsequent mobilization of carbon (C) stored in previously frozen soil organic matter (SOM) have the potential to be a strong positive feedback to climate. As the northern permafrost region experiences as much as a doubling of the rate of warming as the rest of the Earth, the vast amount of C in permafrost soils is vulnerable to thaw, decomposition and release as atmospheric greenhouse gases. Diagnostic and predictive estimates of high-latitude terrestrial C fluxes vary widely among different models depending on how dynamics in permafrost, and the seasonally thawed 'active layer' above it, are represented. Here, we employ a process-based model simulation experiment to assess the net effect of active layer dynamics on this 'permafrost carbon feedback' in recent decades, from 1970 to 2006, over the circumpolar domain of continuous and discontinuous permafrost. Over this time period, the model estimates a mean increase of 6.8 cm in active layer thickness across the domain, which exposes a total of 11.6 Pg C of thawed SOM to decomposition. According to our simulation experiment, mobilization of this previously frozen C results in an estimated cumulative net source of 3.7 Pg C to the atmosphere since 1970 directly tied to active layer dynamics. Enhanced decomposition from the newly exposed SOM accounts for the release of both CO2 (4.0 Pg C) and CH4 (0.03 Pg C), but is partially compensated by CO2 uptake (0.3 Pg C) associated with enhanced net primary production of vegetation. This estimated net C transfer to the atmosphere from permafrost thaw represents a significant factor in the overall ecosystem carbon budget of the Pan-Arctic, and a non-trivial additional contribution on top of the combined fossil fuel emissions from the eight Arctic nations over this time period.