James Lovelock is an interesting character. He has a medical degree and has successfully designed a number of scientific instruments, but he's probably most famous for some of his big ideas, which range from specific geoengineering proposals to the Gaia concept, which proposes that the planet's geology, biology, and atmosphere interact in a complex, self-regulating system.
In recent years, his attention has turned to climate change and, unfortunately, he's largely decided to skip brushing up on science before making grandiose predictions. After having suggested that the human population on Earth would be whittled down to a handful of survivors this century, he's now backed away from these claims—and has gotten nearly as many things wrong in the process of doing so.
Lovelock's original projections weren't made in a scientific journal; instead, they graced the opinion pages of The Independent. And his views were rather opinionated. "As the century progresses," he wrote, "the temperature will rise 8 degrees centigrade in temperate regions and 5 degrees in the tropics." The consequence? Massive upheaval, according to Lovelock. "Before this century is over, billions of us will die and the few breeding pairs of people that survive will be in the Arctic where the climate remains tolerable."
What did he base these figures on? It's very hard to tell. At the time, the most recent IPCC report had concluded that the planet would warm by between 1.4 and 5.8°C by the end of the century—well below Lovelock's estimates. And at the time he wrote, the work of preparing the follow-up report was well under way. That narrowed down the uncertainties on those values considerably, with the worst-case emissions scenario indicating a likely warming of about three degrees by the end of the century.
Even if Lovelock's seriously inflated estimates were right, it's not at all clear that the temperature increases he predicts would make the temperate zones completely uninhabitable.
But Lovelock is now working on a new book, and that's caused him to revisit these predictions. In an interview at MSNBC, he correctly recognizes that his earlier predictions were alarmist, but he apparently did not realize why he had gone so wrong. Rather than actually talking to the people who study the climate for a living, he's just decided that, since his own predictions didn't come to pass, nobody must know what's going on. "The problem is we don’t know what the climate is doing," Lovelock told MSNBC. "We thought we knew 20 years ago." Later on, he claims that "we were supposed to be halfway toward a frying world now."
Except we weren't, at least not according to the best scientific estimates available at the time. And, in fact, we do seem to have some idea what the climate is doing. Most of the last decade has seen relatively stable temperatures, but many similar periods exist in the instrument records, despite the overall upward trend in temperatures. And scientists have also identified many factors that drive short-term variability in the climate. In fact, researchers have published a paper that indicates that, once the major drivers of short-term variation (El Niño, volcanos, and the Sun) are accounted for, the global temperature has continued a general upward trend.
In short, Lovelock's predictions never reflected the scientific consensus and, whatever prompted him to revise them, it didn't seem to involve talking to anyone who actually knows climate science.
For many, the debate over the climate has become a polarized one, with self-labeled skeptics facing off against alarmists. This view isn't very useful, in that it ignores the fact that the vast majority of climate scientists reside somewhere in the middle, and are producing research that suggests both extremes are wrong. But the view is helpful in that it highlights how Lovelock shares so many features with the extreme skeptics, including a misunderstanding of the state of climate research and a willingness to make big pronouncements that are based on little more than their own opinions.