Let’s start the discussion with this: As defined by the IPCC, climate change either does not exist, or it exists everywhere at all times.
The IPCC says “Climate change refers to a statistically significant variation in either the mean state of the climate or in its variability, persisting for an extended period (typically decades or longer).” Clearly from this definition IPCC scientists never anticipated the possibility that the variation and/or its mean state should be undefined in the sense of mathematical convergence, which will be true for most fractal distributions. As the outcome of a chaotic process, most, perhaps all, weather related variables will have high fractal dimension, and many will have non-convergent moments. This happens in chaotic systems because the mean state is forever changing (like the DJ Industrials) and is not static with stable fluctuations (like your checking account). In turn, all subsequent data samples beyond a training period will likely be “statistically significant”, for which the only solution is a heroic effort at averaging (think PCA) and or “outlier rejection” (think dropping parts of data sets). Once upon a time it was thought that if we could just get enough data points and subtract enough cycles, all data would be smooth and regular. We now know that the universe is not fundamentally smooth, and our little planet embedded in it is not either.
The IPCC definition of “climate change” is almost certainly undefined in the statistical sense, and perhaps in the scientific as well.
Also:, via Al Fin
Reid A. Bryson holds the 30th PhD in Meteorology granted in the history of American education. Emeritus Professor and founding chairman of the University of Wisconsin Department of Meteorology—now the Department of Oceanic and Atmospheric Sciences—in the 1970s he became the first director of what’s now the UW’s Gaylord Nelson Institute of Environmental Studies. He’s a member of the United Nations Global 500 Roll of Honor—created, the U.N. says, to recognize “outstanding achievements in the protection and improvement of the environment.” He has authored five books and more than 230 other publications and was identified by the British Institute of Geographers as the most frequently cited climatologist in the world.
Q: Could you rank the things that have the most significant impact and where would you put carbon dioxide on the list?
A: Well let me give you one fact first. In the first 30 feet of the atmosphere, on the average, outward radiation from the Earth, which is what CO2 is supposed to affect, how much [of the reflected energy] is absorbed by water vapor? In the first 30 feet, 80 percent, okay?
Q: Eighty percent of the heat radiated back from the surface is absorbed in the first 30 feet by water vapor…
A: And how much is absorbed by carbon dioxide? Eight hundredths of one percent. One one-thousandth as important as water vapor. You can go outside and spit and have the same effect as doubling carbon dioxide.