Net ecosystem exchange of carbon greenhouse gases in high arctic ecoregions

人类活动使全球大气中温室气体(GHGs)、二氧化碳(CO2)和甲烷(CH4)的浓度上升到一定程度，导致地球气候系统明显和前所未有地变暖。在北极高地地区尤其如此，在过去的一个世纪里，那里的年平均气温上升速度几乎是全球的两倍。目前的气候模型预测，到2100年，在加拿大北极的某些地区，秋冬气温将上升高达9摄氏度，而年降水量可能会上升35%。这种变暖和湿润预计将导致永久冻土退化和冰川融化、地表径流增加、池塘形成和/或干燥，以及景观上植被生长(即初级生产力)的增加。在北极高地的极地沙漠地区，如果苔原植被在沙漠生态系统中定居，以应对日益加剧的变暖和湿润，则可以通过初级生产将大量二氧化碳从大气中隔离出来。相比之下，在土壤中有机碳储量较大的地区，永久冻土退化导致的土壤活动增加可能会导致二氧化碳和甲烷分解和释放到大气中的增加，从而对全球气候变暖产生积极的反馈作用。我们建议量化气候变化对埃尔斯米尔岛库蒂尼帕克国家公园陆地和水生景观中二氧化碳和甲烷净交换的影响。在所研究的最北端地貌进行的这种新的全面测量，对于确定该区域目前是处于净初级生产力阶段还是净分解阶段、未来变暖将导致温室气体对大气的正反馈还是负反馈以及北极生态系统在未来气候变化轨迹中将发挥什么作用至关重要。从社会经济的角度来看，初级生产力为驯鹿、麝香等食草性动物和包括鱼类在内的众多水生生物提供能量。因此，了解北极高地地区二氧化碳的净交换对于预测用作因纽特传统食物的某些生物的丰度可能会因气候变化而发生变化非常重要。

Human activities have elevated global atmospheric concentrations of the greenhouse gases (GHGs) carbon dioxide (CO2) and methane (CH4) to levels that have resulted in an unequivocal and unprecedented warming of the Earth's climate system. This is especially true in the high Arctic, where in the past century average annual temperatures have increased at almost twice the global rate. Current climate models predict that in certain regions of the Canadian Arctic, by 2100, autumn/winter temperatures will increase by up to 9 C, while annual precipitation will likely rise by 35%. Such warming and wetting is anticipated to result in permafrost degradation and glacial melt, increased surface runoff, pond formation and/or drying, and increased vegetation growth (i.e., primary productivity) on landscapes. In polar desert regions of the high Arctic, large amounts of CO2 could be sequestered from the atmosphere through primary production if tundra vegetation colonizes the desert ecosystem in response to increased warming and wetting. In contrast, in regions with large stores of organic carbon in soil, the increased soil activity that will result from permafrost degradation may cause increased decomposition and release of CO2 and CH4 into the atmosphere, positively feeding back on global climate warming. We are proposing to quantify the impacts of climate change on the net exchange of CO2 and CH4 from both terrestrial and aquatic landscapes in Quttinirpaaq National Park, Ellesmere Island. Such new and comprehensive measurements, at the most northerly landscape ever studied, are essential to determine if this region is currently in a phase of net primary productivity or net decomposition, whether future warming will result in positive or negative feedbacks of GHGs to the atmosphere, and what role Arctic ecosystems will play in future trajectories of climate change. From a socio-economic perspective, primary productivity provides energy for herbivorous animals like caribou, muskox, and numerous aquatic organisms including fish. Thus, understanding the net exchange of CO2 in high Arctic landscapes is important for predicting how abundances of certain organisms used as Inuit traditional foods may be altered due to climate change.