So much of government policy is now about reducing carbon emissions on the basis that the earth is heating-up.
But measuring the earth's temperature is not easy.
The traditional way, still used by the United Kingdom's Meteorology Bureau and NASA's Goddard Institute of Space Studies (GISS), involves collating data from weather stations across the world.
These are based in places as cold as Siberia ranging through to the hot tropics of Indonesia.
The number of weather stations has changed with time and many weather stations, even in the United States, are not well maintained and positioned in wrong places -- including next to new air conditioning outlets.
There had been many stories in the local and international media suggesting that last month was unusually cold.
It snowed in the Blue Mountains, and again last weekend as far west as Orange.
London experienced its first October snow since 1922 -- ironically as the British Parliament debated a new climate change bill.
I saw a report of the "the worst snowstorm on record" in Tibet -- 144,400 head of livestock dead.
Then, contrary to expectations, GISS published a temperature anomaly for October showing global warming and not just a bit of warming.
It was reporting a +0.88°C -- the anomaly was the largest ever for October, and one of the steepest jumps in global temperatures ever recorded.
Two Internet web blogs, one run by US meteorologist, Anthony Watts, and another by Canadian statistician, Steve McIntyre, were quick to find one of the errors -- many temperature records from Russia were not based on October readings at all, but rather figures for September that had simply been carried across.
It is much colder in Siberia in October than in September.
The Goddard Institute admitted the blunder and admitted that it was the bloggers who had discovered it.
However, when GISS published the correction it was evident that while adjusting down the temperatures for Russia, they adjusted up the temperatures for Australia and the Canadian Arctic.
Apparently the Australian data was not in when GISS did the original analysis which begs the question: What was the basis for the first guess estimates for Australia?
It seems extraordinary to me that governments across the globe are planning and implementing expensive and intrusive policies based on the notion the earth is warming, but there doesn't appear to be a lot of quality control on much of the data actually driving this mania.
An alternative to the weather station data is satellite data which has been collected since 1979 also by NASA.
But this doesn't show significant global warming and perhaps for this reason is rarely quoted by politicians and climate scientists who have hitched their reputations to the so-called climate crisis.