What it is safe to claim about climate change

This week's TCS exclusive:

The only way to save the planet is to distort the truth.

Sceptical? Good - there is life in democracy yet. But in discussions of global warming fact and fiction frequently blur.

Climate change is the single greatest threat to mankind in the 21st century. But specific weather events can rarely be explicitly linked to climate change; the troposphere is far to complex a system to allow such categorical connections. Nevertheless, those championing action to limit the impact of global warming often invoke specific weather events to buttress their case, and the public doesn’t seem to pay attention unless they do. Can a distinct lack of candour be justified if it serves to help avert global climatic catastrophe?

Scientists and politicians rising to the challenges posed by global warming face a dilemma: humanity has long taken Gaia as a resource to exploit rather than protect, and will only tolerate the inconvenience of saving her if it otherwise stands to suffer itself. The warnings of the scientific community, however, have never been enough. The Intergovernmental Panel on Climate Change felt able to state in 1995 that “the balance of evidence suggests that there is a discernible human influence on global climate”, and, by 2001, that “most of the warming observed over the last 50 years is attributable to human activities”. Yet it took Hurricane Katrina to force the realities of global warming into the American popular consciousness, while current water shortages in Australia were similarly needed to stimulate our antipodean cousins. In making the case for a concerted response to the prospect of severe climatic dislocation, the persuasive effects of specific weather events have proved invaluable. Climate change is an otherwise diffuse, long-term and uneven process; extreme weather allows climatologists to illustrate its catastrophic potential. Shrinking glaciers simply don’t have the propagandistic value of devastated cities.

But is it dishonest to connect climate change with meteorology? Not if the link made is indirect. Climate models do indeed project extreme weather conditions of increased intensity and frequency as the earth heats up. Such was, quite legitimately, the central thrust of Al Gore’s An Inconvenient Truth. But we are on dangerous ground if we make the further claim of a direct causal link between recent global warming and specific meteorological disasters, for humanity has long borne crippling droughts, floods and hurricanes. Littering his documentary with references to the 2005 devastation of America’s Gulf Coast, Gore goes on to claim that “what changed in the US with Hurricane Katrina was a feeling that we have entered a period of consequences”. His Oscar-nominated documentary demonstrates the worrying propensity for slippage between claims of direct and indirect connection. Far from an ‘inconvenient truth’, to cite Katrina as evidence of the impact of climate change is a convenient fiction. Concluding that Katrina was the consequence of global warming is blurring the facts to suit a political agenda.

But if doing so creates a mandate to mitigate climate change, perhaps muddying the issue can be defended. Being a stickler for accuracy today will seem a perverse luxury in 50 years time if central London is underwater. Scientists need to keep global warming in the news if politicians are to have a hope of convincing their citizens to make painful sacrifices. As the costs of climate change limitation begin to bite, and as other causes jostle with global warming for politicians’ and the public’s attention, there will be an ever greater temptation to bind all weather related news with climate change. But this would be profoundly disingenuous, and carries unjustifiable dangers. With climate-change sceptics ready to expose any fallacy, increasingly tenuous claims risk undermining the hard science on which global warming rests. Furthermore, human induced global warming may be the first truly global challenge humanity has faced, but it won’t - unless climate change cripples civilisation beyond recognition - be the last. We owe it to future generations not to devalue the notion of expert opinion. Climate change is a subject in which passions run high and immediate action is needed; the exaggeration of high spirits can perhaps at times be excused. But the truth should not be sacrificed along with our cheap flights and 4x4s.