CS Lewis called this person the “embarassing enthusiast”. A person very committed and very verbal about your common religion, yet someone who occasionally discredits your own views by advancing weak arguments to support it. What to do with such a person’s views? You cannot oppose them—for that would work against your own. Yet you cannot endorse them either, for you want your creed to be built on unshakable foundations.

I started feeling that way about Al Gore when I read his book, An Inconvenient Truth. Mr Gore’s commitment to curbing world carbon emissions is commendable. We have arguably never seen someone deliver such a passioned message with such energy and impact. And I happen to agree, on the basis of the physical evidence we have, that efforts must be taken to diminish man-made CO2 emissions. So I had hoped that Mr Gore’s book would deliver a message that would be both emotionally and factually flawless—but as it turns out, some of his facts should have been checked.

Last 10 April I was a guest in a meeting of Toastmasters International (EPFL). One of the speakers delivered a wake-up call to all of us who would blindly believe anything coming out from the climate-change lobby. In particular, he pointed out that the famous correlation between CO2 concentrations and global temperatures observed for the past 100,000 years in ice core data, and used as one of the strongest arguments by Mr Gore, is not what we think. There is a correlation, yes—provided the CO2 data is shifted 800 years behind the temperature data.

The original paper from which this data came happens to be on my thesis’s bibliography, so I checked this claim. And sure enough, the authors of this paper show quite clearly that the the CO2 data lags behind the temperature data by 600±400 years—suggesting that historically, CO2 concentration increases have been caused by temperature increases, and not the other way around.

I am surprised that climate-change skeptics have not pointed this out before. But it does not really matter, for the current global warming does happen within the same time frame as a dramatic increase in CO2 concentrations. I do not need to look several ice ages in the past to know that. I only wish Mr Gore had done so too before using this argument.