I got my first lesson on the subject of climate change more than 10 years ago. My tutor was an internationally famous climate scientist at a major Ivy League university. Unlike most lectures I have heard from professors, this one was brief, to the point and extremely enlightening.

At the time I was a columnist for the New York Daily News, recently arrived in the United States after more than 30 years in Israel. I had heard about global warming, of course, but I hadn’t thought much about it. Israel has other, more pressing issues.

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In May 2001, the United Nations Intergovernmental Panel on Climate Change published its third report, which got a lot of media attention. I looked through it and realized immediately that I had no chance of understanding the science.

I was in good company – I doubt there are half a dozen journalists in captivity who can actually understand the mathematical and chemical formulas and computer projections. That’s what press releases are for.

One item got my attention. It said: “Projections based on the Special Report on Emissions Scenarios suggest warming over the 21st Century at a more rapid rate than that experienced for at least the last 10,000 years.”

I called the professor, one of the authors of the report, for a clarification (he remains nameless because we were off the record). “If global warming is caused by man-made emissions,” I asked, “what accounts for the world warming to this same level 10,000 years ago?”

There was a long silence. Then the professor said, “Are you serious?”

I admitted that I was.

The professor loudly informed me that my question was stupid. The panel’s conclusion was indisputable science, arrived at after years of research by a conclave of the world’s leading climate scholars. Who was I to dispute it?

I told him I wasn’t disputing it, just trying to understand how, you know, the world could have been this hot before without the help of human agency. Maybe this is just a natural climate change like ice ages that once connected continents and warming periods that caused them to drift apart or …

At which point I heard a click. The professor hung up on me. At that exact moment I became a climate skeptic. I may not know anything about science, but I have learned over a long career that when an expert hangs up in the middle of a question, it means that he doesn’t know the answer.

This isn’t shocking. Experts, even on subjects less complicated than what the world’s temperature will be in 200 years, are often wrong. One tip-off is when they argue by assuring you that everybody smart already knows they are right.

I was reminded of this encounter the other day while reading a Time Magazine cover story titled, “Eat Butter: Scientists labeled fat the enemy. Why they were wrong.” The article chronicled the decades-long consensus, backed by official U.S. government policy as well as a militant (and self-interested) scientific establishment, that fat was a killer. According to Time, this was “so embedded in modern medicine and nutrition that it became nearly impossible to challenge the consensus.” Scientific journals refused to publish data challenging this orthodoxy. People who did, like Dr. Robert Atkins, were derided as quacks.

Now that consensus has flipped (Time Magazine doesn’t publish articles outside any current consensus). It may flip again someday as we learn even more about nutrition and health. But for now, the danger of eating fat – once an unshakable tenet of settled science – is out of intellectual fashion. People who have virtuously deprived themselves of t-bones, ice cream and cheesecake are now left with egg on their faces. It is a reminder that bad science, backed by a politicized posse of experts, can have distasteful consequences.

Another recent article, this one in the New York Times, also caught my eye. It reported that a submerged forest in Wales has suddenly re-emerged, revealing traces that humans had lived there before the sea rose after the last ice age. “About 10,000 years ago, temperatures warmed sharply, by eight to ten degrees Fahrenheit,” said Dr. Martin Bates, a geoarcheologist called in to examine the situation. The footprints found in the sediment belonged to “refugees of prehistoric climate change,” he said (happily, Wales has since been repopulated).

Dr. Nicholas Ashton of the British Museum, a participant in the project, was philosophical. “We can reconstruct the climate and climate change nearly one million years ago,” he said. “The big lesson is, we have to adapt. Whether we like it or not the climate will change – it always has.” He quickly added that human beings were now “accelerating that change.” The Times reporter didn’t ask him how much the change was accelerating, or what, besides people, might be causing an eons-old phenomenon. Perhaps she didn’t wonder. Or maybe she didn’t feel like getting hung up on by an expert.