After 13 years of writing this weekly column I have become inured to criticism, to which I rarely respond, but the letter by Jim Salinger published on the page opposite on Monday demands a reply.

Typical of patronising PhDs, Dr Salinger labels me a "climate change denier". That is downright dishonest. However, it is understandable considering that those who peddle the CO2-is-the-cause-of-global-warming fallacy rely on pseudo-science which is in itself dishonest.

I am not, and nor are the many, many people - scientific and lay - who agree with me, a climate change denier. We cheerfully admit that our climate is changing. It would be hard not to, since climate change has been happening since the Earth was created.

It might even be warming, at least in some parts of the world, but having just suffered the longest and coldest winter since the 1960s in Rotorua, I have real cause to doubt that it is happening here.

My scepticism grows when I note the fact that the Franz Josef and Fox glaciers are increasing in ice, that the ice melt across the Antarctic during the summer (October-January) of 2008-09 was the lowest ever recorded in satellite history, that western Antarctica has had a major increase in ice lately, and that there are 200-odd peaks in the Himalayas that are increasing drastically in ice and snow.

But you never read in the press of these things for some reason or another, just as we never read any of the copious material available, much of it peer-reviewed, which questions the effect of man-produced CO2 on global warming.

So let's take a look at one of the most recent papers, published last month in Economic Analysis & Policy, the journal of the Economic Society of Australia.

Headed, "Knock, knock: Where is the evidence for dangerous human-caused global warming?", it is written by Robert M. Carter, adjunct research professor in the Marine Geophysical Laboratory at James Cook University, Townsville, and at the University of Adelaide. A geologist, he specialises in palaeoclimatology, stratigraphy, marine geology and environmental science.

In the conclusions to his paper he writes: "To focus on the chimera of human-caused greenhouse warming while ignoring the real threats posed by the natural variability of the climate system itself is self-delusion on a grand scale.

"That human-caused climate change will prove dangerous is under strong dispute among equally well-qualified scientific groups. The null hypothesis, which is yet to be contradicted, is that observed changes in climate or climate-related phenomena are natural unless and until it can be shown otherwise.