CO2 Approaches 400 ppm yet Temperatures Remain Flat

CO2 Approaches 400 ppm yet Temperatures Remain Flat
May 17, 2013

James M. Taylor

James M. Taylor is senior fellow for environment and energy policy at The Heartland Institute, and... (read full bio)

Global warming alarmists are breathlessly filling the media with sensationalist reports of carbon dioxide levels approaching 400 parts per million (that’s 4 parts per 10,000, or a 0.0004 share of the atmosphere, versus just under 300 parts per million, or a 0.0003 share of the atmosphere, prior to the Industrial Revolution). The central message of alarmist global warming theory is that higher atmospheric carbon dioxide concentrations will cause catastrophic global warming. A real-world look at how global temperatures are responding to the rise in atmospheric carbon dioxide increase tells a different story.

Although atmospheric carbon dioxide levels were much higher for much of the earth’s history, 400 ppm is arguably the highest level in at least several hundred years and perhaps thousands of years. Global warming alarmists assert atmospheric carbon dioxide levels were approximately 280 ppm prior to the Industrial Revolution and up until the year 1900 or so, meaning atmospheric carbon dioxide levels rose a little more than 40 percent during the past hundred-plus years.

Assuming for the sake of argument the alarmists’ dubious claim that global temperatures rose by as much as 0.8 degrees Celsius since 1900, and also assuming for the sake of argument the dubious assertion that rising atmospheric carbon dioxide levels are entirely responsible for the gradual warming since 1900, this reveals that a 40 percent increase in atmospheric carbon dioxide levels created merely 0.8 degrees Celsius of warming since 1900. This shows much lower climate sensitivity to atmospheric carbon dioxide levels than claimed by global warming alarmists.

Nor is there any sign of a recent increase in the pace of temperature rise. Global temperatures have been flat for approximately 15 years now, even though atmospheric carbon dioxide levels rose more than 40 ppm (or more than 10 percent) during that time.

Rather than being a harbinger of doom and gloom, the approaching 400 ppm carbon dioxide threshold presents still more evidence that humans are not creating a global warming crisis.

James M. Taylor

James M. Taylor is senior fellow for environment and energy policy at The Heartland Institute, and... (read full bio)