WSJ.com - Whatever Happened to Global Warming?

WSJ.com - Whatever Happened to Global Warming?

 

The U.N. no longer claims that there will be dangerous or rapid climate change in the next two decades. Last September, between the second and final draft of its fifth assessment report, the U.N.'s Intergovernmental Panel on Climate Change quietly downgraded the warming it expected in the 30 years following 1995, to about 0.5 degrees Celsius from 0.7 (or, in Fahrenheit, to about 0.9 degrees, from 1.3).

 

Even that is likely to be too high. The climate-research establishment has finally admitted openly what skeptic scientists have been saying for nearly a decade: Global warming has stopped since shortly before this century began.

 

"The scientific community would come down on me in no uncertain terms if I said the world had cooled from 1998," wrote Phil Jones of the University of East Anglia in Britain in 2005. He went on: "Okay it has but it is only seven years of data and it isn't statistically significant."

 

If the pause lasted 15 years, they conceded, then it would be so significant that it would invalidate the climate-change models upon which policy was being built. A report from the National Oceanic and Atmospheric Administration (NOAA) written in 2008 made this clear: "The simulations rule out (at the 95% level) zero trends for intervals of 15 yr or more."

 

Well, the pause has now lasted for 16, 19 or 26 years—depending on whether you choose the surface temperature record or one of two satellite records of the lower atmosphere.

 

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.