A series of two flat lines can appear to be a continuous warming trend if a linear trend line is fitted because it ignores the step change. McKitrick and Voselgang
Posted on 05/07/2012 12:43:49 PM PDT by Ernest_at_the_Beach
Even most skeptics agree that the world has been warming during the last 50 years, but there is apparently no significant underlying warming trend in 46 out of 47 years of data. Something decidedly unusual happened to the world in 1977 and we don’t know for sure what it was. The world got warmer, and the change “stuck”. But there were no extra emissions of CO2 in that year, so there is no reason to pin this to CO2.
It’s difficult to believe we are not sure – but the last 50 years of warming trend depends on that single stepwise leap in 1977. Look at the graph below. Does it show one strong underlying warming trend, or is it really a trend so insignificant that it wouldn’t exist if there was not a step change that artificially bolstered it?
A series of two flat lines can appear to be a continuous warming trend if a linear trend line is fitted because it ignores the step change. McKitrick and Voselgang
This step effect was first noted by David Stockwell in 2009
The continuous warming appears to be obvious in the records of the lower atmosphere when we draw a linear trend line.
McKitrick and Voselgang (click to enlarge)
But look again at the data, allowing for the step-change in 1977.
McKitrick and Voselgang (click to enlarge)
The problem with step changes is that two flat lines with a rising step change will artificially produce a rising linear trend that is meaningless. McKitrick and Voselgang[i] account for the step change and show that significant warming trends in the low to mid troposphere only occur from 1958-2005 if we include the step-change. If the step change is removed, the underlying trend is not significant. In other words, 46 out of the 47 years of atmospheric data do not produce a meaningful rising trend.
If CO2 is having an impact on our atmosphere it is impossible to say with any certainty what that effect has been.
[i] McKitrick, R. and Vogelsang, T. J. (2011), Multivariate trend comparisons between autocorrelated climate series with general trend regressors, Department of Economics, University of Guelph. [Discussion paper PDF]
Thanks much. I sorta figured it was something like that.
az_gila already posted that they're satellites. Thanks.
Rush: Do dinosaur farts pass the smell test?
Global Warming on Free Republic
The warming from CO2 is steady and gradual, but the storage of the extra heat in the ocean (and loss of heat to the deep ocean) is nonlinear. So we would expect jumps up. The best known jump came with the 1998 El Nino. The 2010 El Nino had no jump (ocean ran out of extra warmth? Negative PDO? can't say for sure).
But the jumps are not "proof" that CO2 has no warming effect or increasing CO2 does not increase warmth
The CO2 in the atmosphere causes the atmosphere to be warmer than it would be without it. The CO2 fluctuates naturally each year, but the year over year rise is from the inability of the ocean to absorb the extra man made CO2. If we stopped creating it, CO2 would turn and drop and be 1/2 way back to preindustrial in about 40 years.
The socialist left conflates catastrophic AGW with benign AGW. The catastrophe is only supported by models and will only occur in a century or two if at all (the melting of Greenland). The left knew this all along so they invented the new catastrophe of weird weather. They of course point to Katrina even though that was a man-made disaster and we have had only one landfalling hurricane since (which had no landfalling hurricane winds). They talk about strong tornadoes out of ignorance (they require cold dry air along with warm moist air and are in a long term decline).
If you want to fight the socialist left then simply point out that their solutions won't work (solar and wind are too diffuse). Point out that the increases in rainfall (if they make that claim) are increases in the water cycle and cause global cooling. There are huge holes in the theory of catastrophic warming without resorting to throwing away well-established greenhouse physics.
When the SUN loses it’s fuel and it expands beyond the orbit of the Earth, what will ABC/CBS/NBC/CNN/environmental wackos.. have to complain about then?
(Think I answered my own question-never mind.)
Much as I hate to admit it global warming is man made - the effect is better known as the Clean Air Act. This legislation mandated that particulate emissions be reduced. It it widely accepted that particulates emitted during volcanic eruptions were the cause of global cooling episodes. Therefore we can blame Congress and President Nixon for the warming that stared in the late 70’s.
I'm sorry, but you are mistaken. That fear was about the Ozone layer, for which they banned certain chlorofluorocarbons (Freon).
“I’m sorry, but you are mistaken.”
My point was not trying to make the direct connection. My point was that these whackos, when confronted with reality, will always find something else to further their cause. :-)
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