Xavier Fettweis

“The article is highly factual. One issue that we have is the lack of data over the Greenland Ice Sheet (both spatially and temporally). Thus some of the claims, although backed by the limited data, are valid; we can’t be sure that we may have missed similar outliers. For example, we can’t be sure that a rain event of the type described did not occur in the period before observations were made or may have occurred somewhere on the ice sheet before in a region without any observations.”