A Pause, Not an End to Warming

In this Op Ed to the NY Times, Richard A. Muller is a professor of physics at the University of California, Berkeley, and the author of “Energy for Future Presidents” explains why climate change skeptics are wrong to conclude from that fifteen years of relatively steady global temperatures that the long term impact of increased levels of greenhouse gases in the atmosphere will not continue to push world temperatures higher in the future.  Thus this a  global warming pause – not a cause for celebration.  [Click for full article.]

In part he states in his op ed:

The global warming crowd has a problem. For all of its warnings, and despite a steady escalation of greenhouse gas emissions into the atmosphere, the planet’s average surface temperature has remained pretty much the same for the last 15 years.

As you might guess, skeptics of warming were in full attack mode as the Intergovernmental Panel on Climate Change gathered in Sweden this week to approve its latest findings about our warming planet. The skeptics argue that this recent plateau illustrates what they always knew — that complex global climate models have no predictive capability and that, therefore, there is no proof of global warming, human-caused or not.  [….]

My analysis is different. Berkeley Earth, a team of scientists I helped establish, found that the average land temperature had risen 1.5 degrees Celsius over the past 250 years. Solar variability didn’t match the pattern; greenhouse gases did.[….]

We don’t fully understand past variations, but there is a theorem in science: if it happens, it must be possible. The frequent rises and falls, virtually a stair-step pattern, are part of the historic record, and there is no expectation that they will stop, whatever their cause. A realistic prediction simply includes a similar variability as an unexplained component.

Of course, there are scientists who thought they had explained the variability. Previous pauses in temperature rise in 1982 and 1991 were attributed to the ash and sulfur aerosols spewed into the atmosphere by the volcanic eruptions of El Chichón in Mexico and Pinatubo in the Philippines, respectively. I never found those attributions compelling; in particular, the eruption of El Chichón was too small to account for the stall in warming that was attributed to it. I suspect it was more likely that the variations were the result of chaotic changes in ocean currents.

Because of the instability of ocean flow, the best evidence of a changing climate may be the land temperature record. It is full of fits and starts that make the upward trend vanish for short periods. Regardless of whether we understand them, there is no reason to expect them to stop. The best statistical test of an observation is to see if it has happened naturally in the past.

  For full article click:  global warming pause – not a cause for celebration.

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