Ice dynamics and glacier changes in northern Canada

拟议研究计划的中心目标是提高对加拿大北部冰川对气候变化的反应程度的认识。当气候变暖时，冰川通常会经历更大的表面融化，并通过增加融水径流失去质量。这一过程已经得到了充分的研究，并构成了当前主要气候影响评估（例如，政府间气候变化专门委员会，2001年；北极气候影响评估，2004年）中提供的海平面变化估计的基础。第二个影响是，表面融化的增加可能会为冰川内部和冰川床提供更多的水，这反过来又可能导致冰川表面运动的增加。目前对这种响应的性质了解甚少，在气候影响评估中几乎完全忽略了冰川动态变化的影响。这一遗漏可能是一个重大缺陷，因为对冰川通量变化的不适当计算可能导致对未来海平面上升的低估。这是因为冰川的广泛加速将把更多的冰移到海拔较低的地方，在那里它们可以更快地融化，并将更多的冰直接移到海洋中（在有潮汐冰川的地方）。这对加拿大北部来说尤其令人担忧，因为那里的冰川和冰帽是世界上除格陵兰岛和南极洲外冰量最大的地方，它们的小体积意味着它们对变化的反应可能比大冰原更快，而且据预测，未来气候变暖在高纬度地区最为严重。

The central aim of the proposed research program is to improve understanding of the extent to which glaciers in northern Canada are responding to climate change. When the climate warms, glaciers generally experience greater surface melting and lose mass via increased meltwater runoff. This process has been well-studied, and forms the basis of the sea-level change estimates provided in the major current climate impact assessments (e.g., Intergovernmental Panel on Climate Change, 2001; Arctic Climate Impact Assessment, 2004). A second impact is that increased surface melting may provide more water to the interior and bed of glaciers, which in turn could lead to an increase in glacier surface motion. The nature of this response is currently poorly understood, and the impact of changes in glacier dynamics is almost completely ignored in climate impact assessments. This omission may be a significant shortcoming as improper accounting of changes in glacier fluxes may lead to an underestimation of future sea-level rise. This is because a widespread acceleration of glaciers would move more ice to lower elevations where it can melt more quickly, and move more ice directly to the oceans (in locations where there are tidewater glaciers). This is of particular concern for northern Canada because the glaciers and ice caps there contain the largest volumes of ice in the world outside of Greenland and Antarctica, their small size means that they may respond more quickly to changes than the large ice sheets, and future climate warming is predicted to be greatest in the high latitudes.