Whatever happened to global warming?

It has been roughly two decades since there was a trend in temperature significantly different from zero. The burst of warming that preceded the millennium lasted about 20 years and was preceded by 30 years of slight cooling after 1940.

This has taken me by surprise. I was among those who thought the pause was a blip. As a “lukewarmer,” I’ve long thought that man-made carbon-dioxide emissions will raise global temperatures, but that this effect will not be amplified much by feedbacks from extra water vapor and clouds, so the world will probably be only a bit more than one degree Celsius warmer in 2100 than today. By contrast, the assumption built into the average climate model is that water-vapor feedback will treble the effect of carbon dioxide.

But now I worry that I am exaggerating, rather than underplaying, the likely warming.

Most science journalists, who are strongly biased in favor of reporting alarming predictions, rather than neutral facts, chose to ignore the pause until very recently, when there were explanations available for it. Nearly 40 different excuses for the pause have been advanced, including Chinese economic growth that supposedly pushed cooling sulfate particles into the air, the removal of ozone-eating chemicals, an excess of volcanic emissions, and a slowdown in magnetic activity in the sun.