Perhaps it is comforting to believe that science is an absolute discipline: immune from fads, fanatics and frauds, untroubled by extremists, evangelists, glory-seekers and bigots. But it is not. It is as vulnerable to the vested interests and biases of its practitioners as any corporate entity or political party.
Uncomfortable truths are suppressed and dubious evidence given undue prominence.
Nowhere is this more worryingly obvious than in the science of climate change. As a field of research it has become so heavily politicised that opposing views are spoken of in terms of religion: believers and non-believers, with the accent being on the righteousness of the former and the benighted state of the latter.
Those who believed scientists to be relentless seekers of the truth will have been shocked by the row sparked by a hacker who got hold of emails sent by staff at the University of East Anglia.
It has been claimed that the emails exchanged by members of the university's Climate Research Unit showed statistics had been finessed using 'tricks' and material that didn't fit the computer model of Climate Change presented to the Intergovernmental Panel on Climate Change (IPCC) was allegedly suppressed.
In my book Heaven And Earth, I hinted at the existence of this sort of activity and was pilloried by those who have everything to gain from keeping the climate-change gravy train rolling. Because that is what it has become.
Sensationalist theories are generated by scientists who have evolved into professional alarmists who can influence the IPCC and reap rewards in research grants and fame. The trouble is that the only way to protect this position - and transmit their message of doom and gloom - is for the elite little coterie of climate comrades in the UK and United States to ignore geology, archaeology, history, astronomy and solar science. You see, these are the things that don't fit.
The reality is that the Earth has been here before, it has been here through worse and it is still, resolutely, here today. Climate-change theory and the dire prognosis given by its proponents is just wrong.
Look at the facts. Earth is a warm, wet, greenhouse planet. There has been ice on its surface for less than 20 per cent of its history, and in the geological past there have been six great ice ages. Two ice ages were characterised by ice at the Equator, with sea levels rising by up to 5,000ft. That is sea-level change!
Five of the ice ages saw a far higher atmospheric carbon-dioxide content than at present. So carbon dioxide could not have caused past climate changes. Indeed, early Earth had 1,000 times more carbon dioxide in the atmosphere than now - yet there was no runaway greenhouse effect, tipping points or acid oceans.
The initial source of the two main greenhouse gases, water vapour and carbon dioxide, was volcanoes. Water vapour is still the main greenhouse gas. Once oceans formed and life appeared, carbon was then recycled between the oceans, atmosphere, soils, life and rocks. Carbon dioxide is a plant food, not a pollutant.
Human activity produces only three per cent of the world's carbon-dioxide emissions each year. One volcanic belch can emit as much as that in a day. Carbon dioxide has a short life in the atmosphere and is absorbed by natural processes that have been taking place for billions of years.
At the normal past rates of absorption, even if we burned all fossil fuels on Earth, the atmospheric carbon-dioxide content would not double.
In past ages it has been naturally absorbed into everything from limestone reefs to soil, rocks and living things. For example, limestone is a very common rock and contains 44 per cent carbon dioxide.
Dissolving carbon dioxide in ocean water has not created ocean acidity. The constant chemical reactions between ocean water and sediments and rocks on the sea floor have kept the oceans alkaline. When we run out of rocks on the sea floor, then the oceans might become acid. Don't wait up!
We are still in an ice age that started 34million years ago, with the climate driven, among other things, by the Earth's orbit, the Sun, oceans and volcanoes. It is vital to remember that time, in a geological sense, is a far broader canvas than any of the detailed vignettes upon which the prophets of doom would have us focus.
There have been long periods of warm times during this current ice age, yet the ice sheets did not melt. They waxed and they waned, as ice sheets still do today.
Ancient climates can be revealed by drilling deep into the Antarctic ice for samples of what was snow thousands of years ago. These show climate cycles have a temperature peak at least 800 years before the peak in carbon dioxide.
So climate change evangelists who insist that carbon dioxide drives climate change have turned the truth on its head - the rise in atmospheric carbon-dioxide content followed rather than heralded temperature increases.
Climate is cyclical. The current cycles follow a pattern of about 90,000 years of highly variable glacial conditions followed by around 10,000 years of benign interglacial conditions. The current interglacial period started more than 12,000 years ago.
We are due another glaciation.
At the end of the last glaciation, temperature fluctuated wildly. At one time there was a 15C natural temperature rise in 20 years. Now THAT is global warming. Yet still, humans thrived.
The peak of the current interglacial was 6,000 years ago when the sea level was almost an inch higher than now and temperatures were 5C higher than at present. The rate and amount of temperature change at present is no different to past times.
Sea levels rose by 2cm per year between 12,000 and 6,000 years ago - still part of the present interglacial - a degree of change far greater than anything observed today.
During the last glaciation, land loaded with ice sank. That land is now rising. For example, Scotland and Wales are rising and eastern England is sinking. During the last glaciation, people walked from Europe to England, from Russia to Alaska and from Papua New Guinea to Tasmania. The English Channel was a river.
During previous interglacials, coral reefs and other life thrived. Each time sea level rose, coral atolls expanded. This may be startling to those fed a diet of climate change by scaremongers, but it is not new: Charles Darwin was writing about it in 1842.
There have been smaller-scale climate changes in the present interglacial. Some are cyclical and driven by solar, ocean, tidal and orbital cycles. Others, such as volcanically driven changes, are random.
Life thrived during warm times and life suffered in cool times. Great civilisations collapsed when it was cool.
It was so hot during the 600-year-long 'Roman warming' that grapes were grown as far north as Hadrian's Wall. Sea levels did not rise and polar ice did not vanish. Some Alpine glaciers disappeared, only to appear later. The cold Dark Ages followed: starvation, rampant disease and massive depopulation occurred.
A 400-year warm period followed. The Vikings grew barley and wheat, and raised cattle and sheep in parts of Greenland that are now uninhabitable. During this 'medieval warming', there was so much excess wealth generated from generations of reliable harvests that the great monasteries, cathedrals and universities were built.
Yet sea levels did not rise and the ice sheets were not lost. And, significantly, humans could not have driven the Roman and medieval warmings by carbon-dioxide emissions, as there was no industry.
The Little Ice Age followed. There was famine, disease and depopulation. Ice fairs were held on the Thames up until the 1820s. The Little Ice Age ended in 1850. It is no wonder that temperature has increased in the past 150 years - this is what happens after a cold period.
The temperature increase was not even. There was warming from 1860 to 1880, cooling from 1880 to 1910, warming from 1910 to 1940, cooling from 1940 to 1976, warming from 1976 to 1998 and now cooling from 1998.
Each warming period was at the same rate. It was only during the warming from 1976 to 1998 that carbon dioxide increased in parallel with temperature - all other modern warmings and coolings show no relationship to carbon dioxide.
This is the reality, these are the vacillations of the evocative story of our ever-changing planet derived from observation, measurement and experiment.
Why is this story contrary to what we hear? Because sensationalism is so much more lucrative. A climate catastrophe was provided for an anxious public by scientists who had everything to gain by frightening us.
They put forward an ideology that is blind fundamentalism, unrelated to scientific facts. Politicians build new bureaucracies and pose as environmental saviours without having to face the consequences of their actions. Heads must roll.
Meanwhile, the planet will do what it has always done: change.
• Ian Plimer's book, Heaven And Earth: Global Warming - The Missing Science, is published by Quartet Books.