This letter appeared in the Canberra Times of 5 October:

The Bureau of Meteorology (“Rains proof of warming, bureau says”, October 2, p11) attributes our wet September to global warming.

Last year they blamed global warming for our drought.

Isn’t this becoming a bit silly?

Isn’t is even sillier considering that our planet hasn’t warmed for more than 10 years?

Wouldn’t it be a good idea to revisit the science?

Aert Driessen, McKellar

My response appeared in the 7 October edition:

Aert Driessen (Letters, 5 October) claims that the planet “hasn’t warmed for more than 10 years”. No doubt the source of Aert’s bold claim is the usual ludicrous piece of cherry-picking: if you select 1998 – the very top of the biggest El Nino temperature spike in a century – as the starting point, and you ignore the highest quality temperature index compiled by NASA, you can get away with saying that no average annual temperature has been as high since.

But climate is all about long term trends, not short term spikes. Generally you need more than 15 years – preferably 20 or 30 – to identify a clear trend against the background noise of El Nino and La Nina events, big volcanic eruptions, etc.

Every major index of global temperature – the UAH and RSS satellite indexes, the NASA GISS and Hadley/CRU surface temperature indexes, and measurements of the heat stored in the ocean – shows that the underlying warming trend has continued throughout the last decade, and indeed since the 1970s.

Matt Andrews