U.S. Spies Prove Climate Deniers Wrong

Following up on this post, one of Ian Plimer's many ridiculous claims in Heaven and Earth is this one:

The good news is that alpine valley glaciers are not retreating. Measurements of retreats and advances from glaciers in the period 1946–1995 for 246 glaciers show that there is no sign of any recent global trend towards increased glacier melting.

It leaves one with the impression that we've little to worry as the world's glaciers aren't disappearing.

Well, as is being reported in the Guardian, the Obama administration has recently declassified a whole whack of satellite photos of the arctic, and the photo evidence is undeniable: arctic and glacial ice is retreating at an alarming pace. (More on that story here. And a really scary gallery of photos here.)

How could Plimer (and by extension Rex Murphy) get things so wrong? Well, as Enting points out, the first sentence in that quote above doesn't follow from the second. Plimer, it seems, is confusing speed with acceleration. The source he's using there did indeed show that glacial melting is not speeding up from year to year. But that glacial melt isn't accelerating doesn't mean that it isn't happening. In fact, that's exactly what Plimer's source shows (and the spy satellite pictures prove once again): Glacial ice is reteating at a steady (a more literate columnist might say "inexorable") pace.