Climate questions roll on | OPINION

I asked myself this question, after watching and listening to the latest media blitz on climate change.

This blitz was about an opinion piece apparently signed by all those scientists. It was based on a look at the last 40 years of climate data, and predictably "if we don't all DO SOMETHING, the end is nigh".

Call me a sceptic, but one obvious question is whether anyone, journalist or otherwise, has checked that they are all bona fide climate scientists, or just names - 11,000 seems an awful lot.

Another is "why focus just on the last 40 years?"

Having said that, I'm going to take the risk of boring you on this topic (as I've raised it a couple of times in previous columns) and have another look - after all, growing good fruit and vegetables requires an optimum climate.

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First, a general point. People naturally mix with like-minded people, and scientists are no different.

You have a group in the laboratory, then these groups get together every so often at a forum or a conference, and so it goes on.

The point I'm making is that this is like-minded people talking to like-minded people, with the risk that a broader context is missed.

This is just human nature - I'm not making a value judgement but it gives one answer to the question at the start.

Second, more specifically, how did it finish up with 11,000?

I've been exposed over the past half century to literally hundreds of surveys, some asking for my opinion on a particular issue.

Some had a header which stated who had been contacted. Some had a multiplier effect built in ("Please forward this to three of your colleagues").

Often, the line of least resistance was to simply agree to whatever question was being asked, unless you had a violent objection. I confess I haven't had time to follow up on this one.

Third, what is so special about the last 40 years?

The year 1979 was when we arrived in Tasmania but that didn't have any effect on the climate (well, the physical, that is).

This whole climate change "debate" has been going on for a lot longer than that. I confess, again, as in the previous sentence but I'm sure it will show a "significant" rise in carbon dioxide and average temperatures.

Regarding a rise in carbon dioxide, this is not a bad thing for growing good fruit and vegetables, as summarized in a previous column. I repeat the quote from Tom Quirk et al:

"The current level of carbon dioxide is near the lowest on record over the last 500 million years. It is deficient for optimal growth of many crops and vegetables and constrains food production. For this reason, market gardeners for the past 100 years have been adding carbon dioxide to glasshouses to achieve levels near 1000 ppm (0.10 per cent)... Greenhouse grown vegetables show increases ranging from 10pc to 70pc with increasing carbon dioxide levels.

"A higher level of carbon dioxide is especially beneficial to dryland farming areas like Australia, where crops are frequently under stress because of insufficient moisture. With more carbon dioxide, plants have fewer stomata and lose fewer water molecules per carbon dioxide molecule ... this extra benefit of more carbon dioxide to plants in arid regions shows up very clearly in experiments."

It would be illuminating to calculate what the dollar value would be of the increase in global crop yields due to the increase in atmospheric carbon dioxide.

This is why I'm in favour of climate change.

Tom Quirk can be contacted at e-mail: twquirk@labyrinth.net.au