A heated debate
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 skeptical. 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 center of climate science, revealing doubts about data and a determination not to air such concerns publicly, has strengthened these suspicions.