What is a Climate Threshold?

The science, we were told some years ago is settled. But now, it appears, we are not so sure anymore. In 2007, the Intergovernmental Panel on Climate Change (IPCC) warned the world that a climate catastrophe was just around the corner, if we didn’t curtail carbon dioxide (CO2) emissions. The IPCC was awarded a Nobel peace prize for that work. Co-Nobel-laureate Al Gore has made millions from his book and (so-called) documentary film An Inconvenient Truth, prognosticating doom and gloom.

Never mind that CO2 is vital to all life on earth.

Never mind that CO2 is vital to all life on earth. Never mind that a British High Court found Al Gore’s movie full of "sentimental mush." Never mind that the "Climategate"emails showed (possibly criminal) collusion and obfuscation by some of the "independent" scientists who are creating computer models used in IPCC reports. Never mind that temperature records for the last decade or so showed a global cooling trend, not warming. Never mind, that the low-lying islands in the Pacific and Indian Oceans, which were all supposed to be drowning from rising seas and their people fleeing for their lives, actually have been growing in population ever since. Never mind that that the Arctic sea ice is still there (at -40 F/C, you would not expect it to be different). Never mind that the polar bears and the seals are still thriving in the Arctic. Never mind that the penguins are doing fine in Antarctica. Never mind that the Himalayan glaciers have not melted away. Never mind that global CO2 emissions, as estimated by the U.S. Department of Energy (Nov. 2011) rose by 6% from 2009 to 2010, and the global temperature did not budge.

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The latest IPCC revelations

And now to the latest IPCC revelations. In its Summary for Policymakers of the Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX), released on 18 Nov. 2011, it says in chapter D, on Future Climate Extremes :

Projected changes in climate extremes under different emissions scenarios generally do not strongly diverge in the coming two to three decades, but these signals are relatively small compared to natural climate variability over this time frame. Even the sign of projected changes in some climate extremes over this time frame is uncertain.

In other words, for the next decades, the world’s climate could be getting warmer, or colder, or may not change at all. That revelation, most certainly, is different from the imminent climate-disaster predictions offered in the past. Could it just be that the IPCC is beginning to see the light? The human (supposedly CO2-induced) effects on the climate are "relatively small compared to natural climate variability." Climate determined by nature? What a novel idea! Despite the IPCC’s newly found uncertainty in their climate modeling, the report goes into great detail on the effects (including social effects) of so-called climate extremes. Now, what exactly is meant by the term "climate extreme?" Well, the IPCC offers the following definition: Climate Extreme (extreme weather or climate event): The occurrence of a value of a weather or climate variable above (or below) a threshold value near the upper (or lower) ends of the range of observed values of the variable. You may have noticed the introduction of a new term there, namely “threshold.” So, the question then becomes, what is a "climate threshold" or "climate variable threshold "? Neither the text nor the accompanying graphs on climate extremes provide an explanation. In other words, it’s just more obfuscation than explanation. In common parlance, a threshold is a physical boundary, something "you can bump against." There is no such boundary in the climate.