Hotly disputed

Neil Craig (Letters, 22 September) misleads your readers concerning the question of Greenland melting.

The peer-reviewed paper (FKM, J Geophysical Research, 2010) to which he refers, states: “The total extent of ice melt on the Greenland ice sheet has been increasing during the last three decades… The greatest melt extent over the last 2 and a quarter centuries occurred in 2007.”

The lack of statistical significance to which Mr Craig refers concerns that 2007 result, not the general trend.

Moreover, that lack related to the imprecise nature of previous records: the 2007 “melt index” was 2.02 and the next highest was 1928 at 1.64, according to the paper.

However, the 1928 figure of 1.64 was reconstructed from past temperature records correlated to ice melt, and was liable to error, whereas the 2007 figure was directly derived from satellites. Records of sea-level changes since the last glaciation certainly attest to the “massive sea level rises” that Al Gore may have mentioned.

Now they are rising again. Mr Gore’s suggestion that a sea-level rise of 20 feet could be caused by melting of either West Antarctica or Greenland “in the near future” follows from those palaeoclimatic studies, but he should have made clear that his interpretation of “near future” was not this century.

Mr Craig continues to misunderstand that a reduction of 15 per cent of Greenland ice area does not imply 15 per cent ice melting there, and that the 15 per cent figure came from the Times Atlas, not the scientific community (including the Scott Polar Research Institute in Cambridge), which rapidly rebutted it.

Roy Turnbull

Nethy Bridge

Inverness-shire