Per request, I’ve tested the model of global temperature with el Niño, volcanic aerosols, and solar variations. It was suggested using a 15-year time span as a “hold-out” period for validation, but I decided to use longer hold-out period. Hence the model was fit with data from 1951 through 1989, and the period from 1990 to the present to investigate whether or not the model could match data with which it was not trained. I also decided to do this test with the NASA GISS data set.
The results are rather impressive. Here’s how the original data compares to the model fit for the “training period” from 1951 through 1989:
When we use the model it generates to compute the temperature post-1990, and compare that to the observed data, the fit is excellent:
What might be most impressive is that the model for post-1990 uses only the effect of el Niño, volcanic aerosols, solar variations, and a purely linear trend (to estimate the greenhouse-gas impact), and by doing so it faithfully reproduces both much of the fluctuation due to short-term factors and the continuing trend since 1990.
We can also compare the observed data to the model with their linear trends removed, to see how the model fits the short-term effects:
Of course the fit isn’t perfect, but with a correlation coefficient of 0.67 (and remember, that’s after the linear trends are removed) it’s pretty darn good. It’s also reassuring that the model coefficients are well within the uncertainty range of the coefficients fitting the entire time span (as in the previous post).
The model compares to the data over the entire time span 1951-to-present thus:
Impressive indeed, remembering that the model fit is computed using only the data prior to 1990.
All of which confirms that the model is doing a good job matching the effect of el Niño, volcanic aerosols, and solar variation. This means it gives us a realistic appraisal of what’s been happening to global temperature besides those exogenous factors. When we remove them, we get “adjusted” data which better isolates the global warming signal. It looks like this:
Annual averages of same are here (the vertical red line marks the transition between pre-1990 data used to fit the model and post-1990 used for validation):
The essence is the same as emerged from fitting the model to the larger data set: that there has been a steady warming of the planet since about 1976, one which has not shown a “pause” or “hiatus” or “slowdown” — like the eveready bunny, it keeps going, and going, and going …
Which puts the lie to such “pause” claims. But they were already dead anyway; even without removing the influence of exogenous factors, there was no real evidence for a “pause.”
Which leaves us with two inescapable conclusions. First, man-made global warming continues apace. Second, deniers will continue to deny, despite proof their claims are false.
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