When you ask Australians what proportion of climate scientists agree on the reality of human-caused global warming, the average answer is around 58%, despite evidence that the true size of the consensus is 97%.

Australians still think there is a roughly 50/50 debate among climate scientists. This is a huge “consensus gap” between public perception and reality.

A one-person embodiment of this statistic is the Palmer United Party (PUP) Tasmanian Senator-elect Jacqui Lambie. She had this to say about the scientific consensus on [ABC’s Q&A](http://iview.abc.net.au/programs/qanda/FA1307H011S00](http://www.sksforum.org/redirect.php?t=14228&u=http%3A%2F%2Fiview.abc.net.au%2Fprograms%2Fqanda%2FFA1307H011S00):

TONY JONES: If you were to speak to a group of scientists and they were to convince you that climate change is a problem, that it’s caused by global warming and that global warming’s caused by emissions, would you think differently about it? LAMBIE: Well of course I would, but right now I have half the scientists on this side and the other half on this side so, you know…

Crucial votes

Lambie’s views on climate change are based on a fundamental misconception about the scientific consensus on climate change. This wouldn’t matter so much, were it not for two things.

First, Lambie is one of three PUP Senators-elect who, in a bloc with Ricky Muir of the Motoring Enthusiasts Party, potentially represent four of the six votes the government needs to repeal the current carbon policy after the new Senate comes into effect in July.

Second, Lambie’s party leader Clive Palmer is beset with his own confusion about the carbon cycle, recently telling ABC’s Lateline:

If 97% (of greenhouse gas) comes from nature and 3% comes from man and we say we’ve got to reduce it by 1%, we shouldn’t just look at the 3%, the minority section coming from human enterprise; we need to look at the whole concept. If 1 or 2% comes down from nature, surely that’s a good thing and that brings us back into a balance. It’s the total carbon balance you have to look at. But we’re just focusing on this 3%.

Unpicking these misconceptions (which I will do shortly) does not mean advocating one carbon policy over another. But given PUP’s potentially decisive influence, we should at least expect the party’s elected politicians to understand the basic facts so that they might make an informed decision.

Crunching the numbers

So, back to the consensus. If you remember only one number about climate change, this is it. Ninety-seven. This is the percentage of climate scientists who agree that humans are causing global warming.

Several peer-reviewed studies have found overwhelming agreement about this. A 2009 survey of Earth scientists found that among climate scientists actively publishing climate research, 97% agreed that humans were significantly raising global temperature. A 2011 analysis of scientists’ public statements about climate change found that among those who had published peer-reviewed climate research, 97% accepted human-induced warming.

I led a team that examined 21 years of published research on global warming. Among the papers that stated a position on human-caused global warming in their abstract, 97.1% endorsed the consensus. We also invited the authors of the papers to rate their own research. Among the papers self-rated as stating a position on human-caused global warming, 97.2% endorsed the consensus.

Normally, getting scientists to agree with such near-unanimity is like herding cats. At one climate conference, I watched scientists vigorously argue for an hour about where to go for a beer. What does it take to achieve 97% agreement?

It takes evidence. Not just a paper or two. It takes many independent lines of evidence, all pointing to a single consistent conclusion. Human fingerprints are being observed all over our climate. Tell-tale patterns have been measured in the annual cycle, the daily cycle, the structure of the atmosphere and in outgoing infrared radiation. These all point to rising greenhouse gases as the cause of global warming. These human fingerprints also rule out other natural suspects like the sun or volcanoes.

While I find these human fingerprints fascinating and write about them frequently, the average layperson defers to the opinions of experts on climate change. Fair enough. I don’t browse through engineering blogs every time I cross a bridge to reassure myself that the experts did their sums right.

But when the average Australian thinks the consensus is not 97%, but just 58%, there is clearly a public misconception about what the scientists really think.

Why does this misconception matter? When people think climate scientists don’t agree that humans are causing global warming, they don’t support policies to act on climate change. It is a roadblock preventing meaningful climate action. And when an elected politician like Lambie adopts this way of thinking, the effect is even more powerful because she is elected to represent a large swathe of the public.

In the balance

So can we rely on her party leader to set her straight? I wouldn’t hold out much hope, given his recent comments about the contributions of nature versus industry to the climate problem.

Our planet is in balance. Every spring, nature sucks up hundreds of billions of tonnes of carbon dioxide as plants grow. In autumn, the plants decompose and release the carbon dioxide back into the air. This is the natural balance of the carbon cycle. It’s a circle of life kind of thing.

Humans have upset the balance. By emitting billions of tonnes of carbon dioxide into the atmosphere, we’ve raised atmospheric carbon dioxide to levels not seen in millions of years.

In claiming that we should reduce emissions from nature as well as industry, Palmer’s mistake (ironically enough) is to ignore the total carbon balance. He has forgotten to consider the fact that every year, nature absorbs everything it emits. The natural world mops up its own emissions. Industry doesn’t, which is why greenhouse gas levels are climbing overall.

IPCC 5th Assessment Report

Basic facts

So we have a Senator-elect mistaking a near-universal consensus for a 50/50 debate, while her party leader thinks nature is mostly responsible for rising greenhouse gas levels when it isn’t.

These are pretty basic facts about climate science. Getting them wrong doesn’t inspire much confidence that they will come to grips with the more complex policy issue of what to do about the problem.

The final graphic in this article was updated on April 30, 2014, to provide the most recent available IPCC data.