The Scientific Consensus on Climate Change

Matt Ridley has just written his last “Mind and Matter” column for the Wall Street Journal. We will miss the column and wish him the best in his future endeavors.

To mark the occasion Ridley explains how he came to doubt the “settled science” about global climate change.

It ought to be obvious to every sentient soul that the celebrities who are hawking this pseudo-science do not know enough to examine the data and to draw a rational conclusion. Like their mentor Al Gore, they want to belong to the group of right-thinking people who believe in AGW, as it is called, because it is the “consensus” view among scientists.

If you are a know-nothing, you will do everything in your power to be perceived as belonging to the cognoscenti. It doesn’t matter whether you are right or wrong. It matters that your public thinks that you belong to the intellectual elite. Better that than to be considered just another pretty face who makes a living pretending to be someone he is not.

Ridley opens his column by recounting a conversation he had with a friend. The friend asked how Ridley could reject the “scientific consensus” about climate change.

Ridley recounts the conversation:

Last week a friend chided me for not agreeing with the scientific consensus that climate change is likely to be dangerous. I responded that, according to polls, the "consensus" about climate change only extends to the propositions that it has been happening and is partly man-made, both of which I readily agree with. Forecasts show huge uncertainty.

Besides, science does not respect consensus. There was once widespread agreement about phlogiston (a nonexistent element said to be a crucial part of combustion), eugenics, the impossibility of continental drift, the idea that genes were made of protein (not DNA) and stomach ulcers were caused by stress, and so forth—all of which proved false. Science, Richard Feyman once said, is "the belief in the ignorance of experts."

The point has been made before. No harm is done by making it again. The fact that a majority of scientists agree on something does not make it science. Like everyone else scientists are susceptible to the pull of the crowd. Too often, their careers, their promotions and their funding depend on toeing the party line.

Ten years ago Ridley had been convinced that global climate change was “settled science.” Upon reflection and upon examination of further data, he concluded that the science had been falsified to present a view that served the interests of the ideologues who want to return us to the Stone Age.

Ridley explains how he changed his mind:

 A decade ago, I was persuaded by two pieces of data to drop my skepticism and accept that dangerous climate change was likely. The first, based on the Vostok ice core, was a graph showing carbon dioxide and temperature varying in lock step over the last half million years. The second, the famous "hockey stick" graph, showed recent temperatures shooting up faster and higher than at any time in the past millennium.

Within a few years, however, I discovered that the first of these graphs told the opposite story from what I had inferred. In the ice cores, it is now clear that temperature drives changes in the level of carbon dioxide, not vice versa.

As for the "hockey stick" graph, it was effectively critiqued by Steven McIntyre, a Canadian businessman with a mathematical interest in climatology. He showed that the graph depended heavily on unreliable data, especially samples of tree rings from bristlecone pine trees, the growth patterns of which were often not responding to temperature at all. It also depended on a type of statistical filter that overweighted any samples showing sharp rises in the 20th century.

As I said, we will miss Matt Ridley.