Arctic carbon in flux - greenhouse gas budgets in a permafrost watershed

在整个北极地区，永久冻土生态系统正处于过渡阶段。北极景观正在对气候变暖做出反应，例如，融雪时间提前、生长季节延长、永久冻土退化和植被变化。所有这些变化都可能影响北极的碳储量和温室气体二氧化碳（CO2）和甲烷（CH4）的通量，从而在全球范围内减缓或加剧气候变化。然而，我们仍然不确定北极是二氧化碳和甲烷的汇还是源。我的研究项目旨在为加拿大西北地区的一个低北极流域回答这个问题。我们自2004年以来的长期二氧化碳通量测量表明，在大多数年份，北达科他州达林湖的冻土带是大量的二氧化碳汇。然而，我们需要更好地了解这些碳在通过水生途径移动时，有多少会以CH4和CO2的形式损失回大气中。在这些地点，冰冻土壤限制了渗透，并引导水通过陆地生态系统进入众多溪流和池塘，最终进入达令湖本身，水生碳通量预计会很重要。通过开发和验证陆地表面方案和碳循环模型与加拿大地球系统模型的常规耦合，我们将利用我们的结果直接改进加拿大的气候变化建模工作。这些模型对北极冻土带处理的改进将最好地了解北极功能的变化如何影响加拿大和世界各地的未来气候。我们计划通过参加一年一度的苔原科学营，继续与北方的学生和他们的老师和长辈进行教育活动。我们希望就景观如何应对气候变化交换意见，并对冻土带在全球气候中的作用表示赞赏。这些知识对于加拿大北部的人们适应不断变化的环境至关重要，对于全球各地的社区来说，必须对这些预测有信心，采取必要的步骤，为变化做好准备，减少温室气体排放。

Throughout the Arctic, permafrost ecosystems are in transition. The Arctic landscape is responding to a warming climate with earlier snowmelt, longer growing seasons, permafrost degradation, and changes in vegetation, for example. All of these changes may impact Arctic carbon stores and fluxes of greenhouse gases of carbon dioxide (CO2) and methane (CH4) that could either mitigate or enhance climate change at a global scale. However, we are still uncertain if the Arctic is a sink or source for CO2 and CH4. My research program aims to answer this question for a low Arctic watershed in Canada's Northwest Territories. Our long-term CO2 flux measurements since 2004 suggest the tundra at Daring Lake, NT are substantial CO2 sinks in most years. However, we need to better understand how much of this carbon might be lost back to the atmosphere as CH4 and CO2 as it moves through aquatic pathways. Aquatic carbon fluxes are expected to be significant at these sites where frozen soil limits infiltration and directs water through the terrestrial ecosystems into numerous streams and ponds and finally into Daring Lake itself. We will use our results to directly improve Canada's climate change modeling efforts by developing and validating the land-surface scheme and carbon cycle models routinely coupled with Canada's Earth System Model. Improvements to these models' treatment of Arctic tundra will best achieve an understanding of how changes in Arctic functioning may influence future climate here in Canada and around the world. We plan to continue our educational activities with northern students and their teachers and elders through participation in the annual Tundra Science Camp at Daring Lake. We hope to exchange ideas on how the landscape is responding to climate change and impart an appreciation for the tundra's role in the global climate. This knowledge is critical for people in Canada's north working to adapt to a changing environment and for communities around the globe that must have confidence in these predictions to take the steps needed to also prepare for change and reduce greenhouse gas emissions.