Wednesday, March 10, 2010

Climate debate: opinion vs evidence


ABC The Drum, 11 March 2010

What exactly is "balance"? Our society rightly strives for balance, and many issues are deservedly considered by presenting a balanced set of opinions. 

There are however clear cases in which the only balance that matters is the balance of evidencerather than of opinion: Serial killer Ivan Milat's protestations of innocence should not — and did not — balance the evidence arrayed against him. The desire to cure AIDS with garlic and beetroot does not balance the medical consensus that the disease is caused by HIV and can only be beaten by retroviral drugs. And the current wave of sensationalism and distortion cannot balance the scientific consensus that climate change is real and is caused by human emissions.

The current descent of the climate debate into a cauldron of misrepresentations that are at odds with scientific reality must therefore be of concern.

It must be of concern that climate scientists can be publicly accused of having vested financial interests in their research, when in fact Australian research grants cannot be used to top up a researcher's salary.

It must be of concern when segments of the national media frequently distort and misrepresent scientific articles and scientists' statements in complete departure from accepted standards of journalistic honesty and decency.

It must be of concern when segments of the media echo the meme that "global warming stopped in 1998" when in fact all years since 2000 — that is 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, and 2009 — are among the 10 hottest years ever recorded since 1880. The probability of this happening by chance is small.

It must be of concern that the current Leader of the Opposition has publicly dismissed climate science and instead cosily chats with a visiting British aristocrat who is a serial fabricator — an individual who has publicly misrepresented himself as a member of the House of Lords when he is not; who claims to have cured influenza as well as AIDS; who claims to have won the Falkland War by means of biological weapons; who accuses NASA of blowing up their own research satellites; and whose latest pseudo-mathematical pronouncements about climate change are at odds with past ice age cycles. 

It must be of grave concern when the opinions of the same conspiracy theorists who believe that Prince Phillip runs the world's drug trade are given credence by the media when it comes to climate change.

No, balance in media coverage does not arise from adding a falsehood to the truth and dividing by two. Balanced media coverage of science requires recognition of the balance of evidence.

What then is the true balance of evidence on climate change?

Fact is that the most recent survey of thousands of Earth scientists around the world revealed a 97 per cent agreement with the proposition that human activity is a contributor to climate change. This peer-reviewed study clarifies that the present "debate" about climate change is not actually a debate within the relevant scientific community.

Fact is that a recent analysis of nearly 1,000 peer reviewed publications by a prominent historian of science revealed no disagreement with the view that climate change is happening and is caused by human CO2 emissions. If each of those publications were presented on a poster, as is common at scientific conferences, the line of posters would stretch across the Sydney Harbour Bridge and back again. Yes, there are a few dissenting papers that have appeared in refereed journals — but to date none have withstood subsequent scrutiny.

Fact is that there is a strong scientific consensus on climate change and its human-made causes that is exhaustively summarised in the nearly 3,000 pages of the most recent IPCC report that draws on more than 18,000 sources. Tellingly, the lone error about Himalayan glaciers on page 493 of the contribution from Working Group 2 was brought to the public's attention by … an IPCC lead author!

Anyone can experience this scientific consensus hands-on in a few seconds: Google "climate change" and you get nearly 60 million hits. Now go to the menu labelled "more" at the top, pull it down and choose the "scholar" option. 58 million hits disappear. The remaining scientific information will get you in touch with the reality on this planet, in the same way that applying the "scholar" filter after googling "sex" eliminates 500 million porn sites and leaves you with civilised discourse about sexuality. 

Does this indubitable scientific consensus guarantee that the evidence concerning climate change is necessarily irrefutable? 


As with any other scientific fact, new evidence may come to light that can overturn established theories. Two core principles of science are scepticism and falsifiability — that is, scientific facts must be subject to sceptical examination and they must be refutable in principle. New evidence may overturn the current view that HIV causes AIDS, and new evidence may revise our expectation that gravity will have adverse consequences for those who jump off the Sydney Harbour Bridge. Likewise, new evidence may force a revision of our understanding of climate change. 

It is however utterly inconceivable that the current scientific consensus about climate change will be overturned by conspiracy theories that are inversions of reality.

It is utterly inconceivable that the consensus on climate change will be weakened by mendacious misrepresentations in the media that fail to accurately represent the strength of scientific evidence.

It is utterly inconceivable that all the arguments against climate change that have been falsified multiple times will rise from the dead and overturn scientific knowledge. 

Instead, the very fact that many of the roughly 100 falsified "sceptic" talking points are continually reiterated in public draws a clear dividing line between healthy scepticism and arrogant denialism. 

Sceptics seek answers and scrutinise arguments before accepting the current state of scientific knowledge as fact. Denialists dismiss sound arguments, solid data, and experimental evidence in favour of propositions that have long been shown to be flawed.

The world's pre-eminent scientific journal, Nature, therefore refers to those who cling to long-debunked pseudo-scientific conspiracy theories while dismissing the findings of thousands of peer-reviewed studies by their true label — denialists

The potentially devastating consequences of denialism are brought into sharp focus by the sad history of South Africa's AIDS policies. Despite having one of the world's highest rates of HIV infections, the government of President Thabo Mbeki went against consensus scientific opinion 10 years ago and declined anti-retroviral drugs, preferring instead to treat AIDS with garlic and beetroot. Politicians even accused a leading South African immunologist of defending Western science and its "racist ideas" for his insistence on scientific treatment methods. According to a recent peer-reviewed Harvard study, this denialism cost the lives of more than 330,000 South Africans. 

For that, President Mbeki and his associates are now held in richly deserved contempt around the world.

Precisely the same fate awaits denialists of climate change. 

The laws of physics will relentlessly assert themselves, unswayed by public opinion, political shenanigans, or elections. Ultimately, the laws of physics will speak so loudly that no amount of wishful thinking can prevent them from being heard; but because any delay in taking action against climate change will increase the human and financial burden on future generations, it is our responsibility now to cease tolerating lies, misrepresentations, puerile accusations, and conspiracy theories that are unworthy of public discourse in a mature democracy. 

Many spirited conversations about climate change can be had that examine the likely consequences for Australia and evaluate the best course of action — but those conversations must be firmly rooted in the core scientific principles of scepticism and falsifiability and they must not be contaminated by ignorance and denialism. 

Stephan Lewandowsky is a Winthrop Professor and an Australian Professorial Fellow at the University of Western Australia.

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