Until I read the New York Times last week I had not heard of availability entrepreneurs. John Tierney, that paper’s always entertainingly readable op-ed columnist, used the expression in his New Year’s prediction piece warning us we are in “for very bad weather.”

In 2008, he predicted, our television will bring image after frightening image of natural havoc linked to global warming. We will be told that such bizarre weather must be a sign of dangerous climate change — and that these images are a mere preview of what’s in store unless we act quickly.

Mr Tierney is the journalist who brought us the story back in 1990 describing a 1980 wager about natural resources between the economist Julian Simon and the ecologist Paul Ehrlich. “Betting the Planet” has been widely cited and reprinted since then. If you take the time to re-read it you will surely wonder why anyone still takes Paul Ehrlich seriously but that is by-the-by. This latest Tierney column is about climate change and the people who promote it as the major problem confronting the modern world. It deserves to be read in full but this extract gives the flavour:

I don’t know if disaster will come by flood or drought, hurricane or blizzard, fire or ice. Nor do I have any idea how much the planet will warm this year or what that means for your local forecast. Long-term climate models cannot explain short-term weather.

But there’s bound to be some weird weather somewhere, and we will react like the sailors in the Book of Jonah. When a storm hit their ship, they didn’t ascribe it to a seasonal weather pattern. They quickly identified the cause (Jonah’s sinfulness) and agreed to an appropriate policy response (throw Jonah overboard).

Today’s interpreters of the weather are what social scientists call availability entrepreneurs: the activists, journalists and publicity-savvy scientists who selectively monitor the globe looking for newsworthy evidence of a new form of sinfulness, burning fossil fuels.

One of the examples Mr Tierney used to illustrate his point was the way the press seized on Arctic sea ice last year hitting the lowest level ever recorded by satellites as a sign that the whole planet was warming while ignoring that the Antarctic sea ice last year reached the highest level ever recorded by satellites. The coverage of Antarctica ignored the generally cooler temperatures but concentrated on the small area closest to South America where temperatures have warmed and the ice sheet has grown smaller.

Now I am no scientist but I do have a sceptical geologist as a brother who keeps referring me to articles he comes across which suggest that not everything in this climate change debate is as certain as the availability entrepreneurs would tell us. So today I delved into the data collected by all those American NASA satellites which form the basis for much of the argument.

Perhaps I should just let the pictures tell the story.

The maps come from the National Snow and Ice Data Center (NSIDC), located at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado at Boulder, which says it “supports research into our world’s frozen realms: the snow, ice, glacier, frozen ground, and climate interactions that make up Earth’s cryosphere. Scientific data, whether taken in the field or relayed from satellites orbiting Earth, form the foundation for the scientific research that informs the world about our planet and our climate systems.”

In November 2007 on the measure of the Sea Ice Extent the total area was 16.1 million square kilometers which was up from 15.9 million square kilometers in November 2002 and 15.8 million square kilometers in November 1987. Using the second NSIDC measure of Sea Ice Concentration and the figures are 12.0 m. sq. k. in November 2007, 11.5 m. sq. k. in November 2002 and 11.1 m. sq. k. in November 1987.

Make of it what you will but I am moving in to Brother David’s camp.