A heated debate

“What is truth?” That was Pontius Pilate’s answer to Jesus’s assertion that “Everyone that is of the truth heareth my voice.” It sounds suspiciously like the modern argument over climate change.

A majority of the world’s climate scientists have convinced themselves, and also a lot of laymen, some of whom have political power, that the Earth’s climate is changing; that the change, from humanity’s point of view, is for the worse; and that the cause is human activity, in the form of excessive emissions of greenhouse gases such as carbon dioxide. A minority, though, are sceptical. Some think that recent, well-grounded data suggesting the Earth’s average temperature is rising are explained by natural variations in solar radiation, and that this trend may be coming to an end. Others argue that longer-term evidence that modern temperatures are higher than they have been for hundreds or thousands of years is actually too flaky to be meaningful.

Such disagreements are commonplace in science. They are eventually settled by the collection of more data and the invention of more refined (or entirely new) theories. Arguments may persist for decades; academics may—and often do—sling insults at each other; but it does not matter a great deal because the stakes are normally rather low.

The stakes in the global-warming debate, however, could scarcely be higher. Scientific evidence that climate change is under way, is man-made, and is likely to continue happening forms the foundation for an edifice of policy which is intended to transform the world’s carbon-intensive economy into one which no longer spews greenhouse gases into the atmosphere. A lot of money, and many reputations—both academic and political—are involved.

Sceptics claim that this burden of responsibility is crushing the spirit of scientific inquiry. Scientists, they maintain, are under pressure to bolster the majority view. The recent publication of embarrassing e-mails from the University of East Anglia, an important centre of climate science, revealing doubts about data and a determination not to air such concerns publicly, has strengthened these suspicions.

There is no doubt that politics and science make uncomfortable bedfellows. Politicians sell certainty. Science lives off doubt. The creation of the Intergovernmental Panel on Climate Change to establish a consensus on the science was an excellent idea for policymakers, who needed a strong scientific foundation for their deliberations, but it sits uncomfortably with a discipline that advances by disproving accepted theories and overturning orthodoxies.

The danger of dissent

Some would argue that, in matters of great public import, scientific dissent should be silenced. It can, it is true, do harm. When AIDS first reared its ugly head, no one knew what caused it. Gradually, the virus responsible was isolated, identified and then attacked successfully with drugs designed specifically to inhibit its reproduction. A few scientists, though, refused to accept the evidence, and some politicians used their arguments to justify inaction. Since one of those politicians was Thabo Mbeki, then president of South Africa, hundreds of thousands who might have been saved by an anti-AIDS policy grounded in scientific reality died as a result of his policies.

Yet the damage in that case was done by the politicians. A leader who is determined to pursue a wrong-headed course will always find some scientist to support him. A world in which that were not true would be one in which a dangerously narrow consensus had taken hold.

This newspaper believes that global warming is a serious threat, and that the world needs to take steps to try to avert it. That is the job of the politicians. But we do not believe that climate change is a certainty. There are no certainties in science. Prevailing theories must be constantly tested against evidence, and refined, and more evidence collected, and the theories tested again. That is the job of the scientists. When they stop questioning orthodoxy, mankind will have given up the search for truth. The sceptics should not be silenced.