Net ecosystem exchange of carbon greenhouse gases in high arctic ecoregions

人类活动已使全球大气中温室气体（ghg）、二氧化碳（CO2）和甲烷（CH4）的浓度升高到导致地球气候系统明显和前所未有的变暖的水平。在北极高纬度地区尤其如此，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9摄氏度，而年降水量可能会增加35%。预计这种变暖和变湿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）增加。在北极高纬度的极地沙漠地区，如果苔原植被在沙漠生态系统中定居，以应对升温和变湿，那么通过初级生产，可以从大气中隔绝大量的二氧化碳。相反，在土壤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导致CO2和CH4分解和释放到大气中，从而积极反馈全球气候变暖。我们建议量化气候变化对埃尔斯米尔岛Quttinirpaaq国家公园陆地和水生景观中CO2和CH4净交换的影响。在研究过的最北端景观上进行的这种新的综合测量，对于确定该地区目前是处于净初级生产力阶段还是净分解阶段、未来变暖是否会导致温室气体向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何种作用至关重要。从社会经济的角度来看，初级生产力为驯鹿、麝牛等食草动物和包括鱼类在内的许多水生生物提供能量。因此，了解北极高纬度地区二氧化碳的净交换对于预测因纽特人用作传统食物的某些生物的丰度如何因气候变化而改变是很重要的。

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.