Weighting climate change in the cryosphere from space

Abstract:

Changes in the cryosphere as a result of climate warming occur at three times the rate of change in lower latitude/lower altitude regions, with immense consequences for human populations such as rapid sea level rise and reduced availability of freshwater resources. These issues are tackled by scientists using remote sensing techniques, in situ data, field parties, and computer models to document changes, understand their underlying physical mechanisms, and constrain numerical models. Ultimately, scientists will work with engineers, social scientists, policy makers, stake holders, and the public to develop and implement adaptation and mitigation strategies. With the advent of space technologies, we now document and inform about ice sheet changes better than ever, continuously, globally, at a precision of a centimeter of water. We have witnessed widespread, growing mass loss in Greenland from ice melt and enhanced glacier flow. Recently, large variations in blocking effect have produced cold snaps followed by extreme summer melts. In Antarctica, we have quantified the mass loss, limited to a few sectors, and documented the greatest acceleration in loss. Uncertainties between glacier loss and snowfall increase persist in East Antarctica, but we recently reduced them by improving constraints on glacial isostatic rebound. At both poles, we have documented how well regional atmospheric climate models reconstruct surface mass balance, including runoff. These efforts are being extended to the World’s glaciers with a new generation of reanalysis data and global climate models, which in turn helps better constrain models. Assessments of the mass balance of the World’s mountain glaciers provides a global validation of climate models and information about the impact on freshwater resources. In High Mountain Asia, for instance, where glacier melt is an important participant, we find that the evolution of freshwater resources is more strongly affected by changes in precipitation. With anticipated future advances in gravity, altimetry and other space missions, high resolution climate models and in situ data, we are moving beyond establishing the state of balance of the cryosphere into looking at the details of how it will affect human systems globally and regionally with increasing reliability.