David Hardie, in his efforts to debunk global warming (The Weekend Sun, October 21), displays some strange theories on the properties of water. Like ‘water remains at a constant volume while a liquid regardless of temperature'. It obviously doesn't. Or ‘ice floats due to air incorporated'. Nope. It floats because water starts expanding when being cooled, just before it freezes. He asks: ‘Where is the ice to raise sea level by the amounts claimed?' The answer: Mainly in Antarctica where ice up to 4km thick covers a 97 per cent of a continent much bigger than Australia (capable of raising worldwide sea levels by over 60 metres if it all melted) and on a smaller scale in Greenland, capable of causing a 6 metre rise. Note that: the process is already well underway, as is the expansion of the ocean as sea temperatures rise.

He also claims ‘we are presently experiencing the lowest temperatures for up to 100 years'. In fact, NZ and the rest of the world have been experiencing at least three years of the highest temperatures on record despite occasional polar blasts reaching the mid latitudes. This phenomenon is due to a weakening of the polar vortex surrounding both the Arctic and Antarctic, normally ‘ring-fencing' in most of the cold air where rightly it belongs – the Polar Regions – which have consequently suffered heatwaves of up to an astounding 40 degrees Celsius.

I suggest David Hardie's version of physics does little credit to his apparent mission of disproving global warming and climate change.

Peter Otway, Omokoroa.