Scientists don't believe in climate change? The world is cooling. It's all caused by solar activity? Or is it? Here's our brief summary of climate denial.

What is climate denial / scepticism?

Climate change deniers argue climate change is not proven science. They generally follow this by arguing it would therefore be wrong to risk "wrecking the economy" trying to prevent what may be a non-existent problem.

Deniers or sceptics?

Put simply, sceptics aren't sure about climate change (or that humans are causing climate change) but don't dismiss the possibility, while deniers say it isn't happening and don't engage in genuine debate on the issue.

However, this distinction is muddied because so many deniers claim to be sceptics (the term denier being too negative). This has made the term "denier" and "sceptic" interchangeable in practice.

General criticism of climate denial / scepticism

Critics say deniers / sceptics are not engaged in a genuine scientific debate and, indeed, show contempt for scientific methodology. They recycle discredited  claims, take data out of context, misuse statistics, deliberately make logical errors, and don't submit their work to peer-reviewed scientific journals. Critics claim their aim is simply to create public doubt about climate change by creating an illusion of scientific debate when in fact few scientists dispute the reality of climate change. In reality, while there is plenty of scientific debate on the details, there is a broad scientific consensus that humans are contributing to a global warming through the emission of greenhouse gases. This tactic of false doubt was used by the tobacco industry to fight a rearguard action long after the harmful effects of smoking were established. See this Sydney Morning Herald article.

Climate denial claims

There is no scientific consensus that climate change is happening.

Even if you reject the consensus, there is no doubt a widespread scientific consensus on climate change exists. The International Panel on Climate Change (IPCC) is a UN body that attempts to reflect scientific consensus on climate change. It consults many thousands of scientists studying various aspects of climate. The IPCC reports indicate an overwhelming majority of scientists think human-induced climate change is real. Chief scientists in the UK and Australia and elsewhere have publicly agreed with this view. Independent reviews for the UK and Australian governments (the Stern and Garnaut reports) both concluded climate change is real. Of course, a small number of individual scientists disagree. But, equally, others think the situation is far more serious than the IPCC states.

In the last decade the planet has cooled.

Records show 12 of the hottest years since records began in 1850 have come in the past 13 years. However, there has been a slight cooling over the past decade from a record high in 1998. Climate is a long-term, largescale phenomenon influenced by many factors; one might expect a temperature graph to have ups and downs and this slight cooling over a few years from a record peak certainly isn't sufficient evidence to say there is a long-term cooling trend. Again, the scientific consensus is that the long-term trend is still upwards.

Scientists are afraid to speak out against climate change orthodoxy for fear of losing funding.

Some scientists may be reluctant to go against their peers. Some climate sceptics may have been denied funding, mainly because their work was not credible. But there is no evidence of systematic funding bias against climate sceptics. On the other hand, sceptical scientists may find funding elsewhere. Britain's premier scientific body, the Royal Society, reported that in 2005, oil giant Exxon distributed nearly $3 million to 39 groups which "misrepresented the science of climate change by outright denial of the evidence that greenhouse gases are driving climate change".

It would be foolhardy to risk damage to the economy to tackle what may be a non-existent problem.

By the same reasoning, it would be foolish to risk damage to the environment to achieve economic growth. So if we have to risk one to protect the other, which is more important. Should we err on the side of the economy or the environment? Surely this is a no-brainer - mankind can always rebuilt an economy, or adapt to life with less resources, as Britain did in WWII or Cuba has been doing since losing Soviet oil supplies. But if we irrevocably change the environment that supports human life, we won't be able to replace it.

Climate naturally fluctuates, with hot and cold eras, mini-ice ages and so on.

True. But studies indicate we are seeing levels of warming not seen in human history. Air samples from bubbles trapped in ice show temperatures are rising faster than at any time in humanity's history. And just because other factors that can affect climate doesn't mean an increase in greenhouse gas isn't causing the current warming.

Solar activity or volcanoes have far more impact on climate than human activity.

Again, true but misleading. Human activity is a small factor in climate but  it may turn out to be the straw that breaks the camel's back, tipping it from one fluctuating but ultimately stable system into a new, warmer state. In any case, surely it would be safest to remove the human contribution to climate change, just in case. Solar activity, often cited by sceptics as the cause of global warming, is factored into climate models. Since the 1970s the sun's energy output and the earth's orbit have been stable, while temperatures have risen - in fact in recent years the sun has been in a "weak" phase with fewer sunspots than usual.

Far from warming, scientific evidence is mounting that the world is entering another ice age.

This idea has been around since the 1970s and hasn't convinced the scientific community yet. The IPCC report considered the evidence and concluded it is "virtually certain" that it isn't going to happen for hundreds of years, and most likely "the next glacial period would not be expected to start within the next 30,000 years."

The world has been getting cooler since 1998

Climate is measured over longer periods and subject to various factors. 1998 was exceptionally hot due to a strong El Nino. Subseqent years have been not quite as hot because the El Nino effect has not been as strong, but still the hottest decade on record. Allowing for El Nino-La Nina cycles, the temperature trend is still clearly rising.

Climate change is a pseudo-religion

Deniers like to throw this line in whenever possible. However, climate change theory is solidly based in the empirical scientific method of analysis of a wide range of data and peer-reviewed publication. The analogy with religious belief (which is by definition not based on empirical evidence) is absurd.

Climate change is a ruse by extreme greenies to bring down consumer capitalism

Some greenies may see climate change as an opportunity for a social transformation, but that doesn't mean climate change isn't happening. On the other hand many quite conservative people have become convinced of the reality of climate change. For instance, Ross Garnaut and Nicholas Stern, appointed by the Australian and UK governments respectively to prepare a report on climate change, are mainstream, apolitical figures who became convinced by the evidence that climate change is happening.

Climate change is a ruse by bankers to make money from carbon trading and the like

Some people will undoubtedly make money from measures to prevent climate change but that doesn't mean climate change isn't happening. (Some people make money out of war but that doesn't mean the enemy isn't real.)

Climate change theory is based upon three or four climate models.

Sceptics claim the whole theory of climate change is built on about a few computer models full of unproven assumptions, including NASA's and The Hadley institute in the UK. But evidence of warming temperature and the link with increasing greenhouse gases is based upon a huge range of information from many scientific disciplines.

Conclusion

It's true. There is not 100 per cent scientific agreement that human-induced global warming is happening. That's not how science works. There are always dissenting views. Climate is complicated and everyone accepts we don't fully understand it. Yes, it may turn out the globe isn't warming - or, if it is, it may be nothing to do with greenhouse gases. But the vast majority of climate scientists believe human activity is causing dangerous global warming. Ask a climate sceptic - how is he qualified to know they are all wrong.  

No-one knows what the consequences will be. We are entering uncharted territory. Rising sea levels could displace billions, leading to "climate wars" over territory and resources. Changing ecosystems could lead to massive species extinction. We could even make the planet unfit for human habitation.

Given this magnitude of risk, it seems sensible to adopt the precautionary principle of eliminating likely human contributions to global warming just to be on the safe side.

Useful websites

Coby Beck's How to talk to a climate sceptic blog 

Sydney Morning Herald: Despite Sceptics' Noise, Consensus is Growing

Tim Lambert's Deltoid Blog

Skeptical Science

The Global Warming Debate

Greenfrye's