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A newly described population of polar bears in southeastern Greenland suggests the potential for climate refugia. 

Abstract. The objective of this note is to provide the backgroundand basic tools to estimate the statistical error of deformation parametersthat are calculated from displacement fields retrieved from syntheticaperture radar (SAR) imagery or from location changes of position sensors inan array. We focus here specifically on sea ice drift and deformation. Inthe most general case, the uncertainties of divergence/convergence, shear,vorticity, and total deformation are dependent on errors in coordinatemeasurements, the size of the area and the time interval over which theseparameters are determined, as well as the velocity gradients within the boundary ofthe area. If displacements are calculated from sequences of SAR images, atracking error also has to be considered. Timing errors in position readingsare usually very small and can be neglected. We give examples for magnitudesof position and timing errors typical for buoys and SAR sensors, in thelatter case supplemented by magnitudes of the tracking error, and apply thederived equations on geometric shapes frequently used for derivingdeformation from SAR images and buoy arrays. Our case studies show that thesize of the area and the time interval for calculating deformationparameters have to be chosen within certain limits to make sure that theuncertainties are smaller than the magnitude of deformation parameters.