If there exists a scientist who can prove to the satisfaction of the world's leaders that global warming - anthropogenic or not - is a myth, he or she will get a Nobel prize and a medal from every government on Earth. Why? Because it will stifle all opposition to the 'business as usual' economic model. Sorry, but I don't think that person exists.
How plausible are AGW theories in general?
I will address that question using the sort of logic that can be programmed into a computer to simulate human intelligence: semantic logic.
Question:
"Is it plausible that humans could cause effect C?"
This breaks down into the two components of plausibility: possibility and likelihood.
Question 1:
"Is it in any way possible that humans could cause effect C?"
Question 2:
"Is it in any way probable that humans could cause effect C?"
If the answer to both questions is a 'yes', however tentative, then the idea that humans can cause effect C is minimally plausible."
If a line of inquiry leads to a theory that is at least minimally plausible, then that theory remains worthy of scientific investigation.
If a line of inquiry leads to a theory that is maximally implausible, then that theory is not worthy of scientific investigation.
By phrasing questions in this way it becomes possible to discuss the science in 'common sense' terms. There is no need to use emotive terms such as 'truth'.
If something is plausible, then the evidence in support of it is more likely to be plausible. Conversly, if something is implausible, then the evidence in support of it is more likely to be implausible. If something is, according to the basic tenets of science, impossible - e.g. perpetual motion - then there is not going to be any valid scientific evidence whatsoever in support of any theory that it is or may be possible.
Climate theories and evidence
The global warming issue can be viewed as three questions:
Is there any such thing as global warming - GW?
Is there any such thing as anthropogenic global warming - AGW?
Can global warming, however caused, itself cause a significant global climate change?
Any evidence purporting to show a yes or no answer to any of the above three questions may be examined in terms of plausibility logic.
The (in)famous hockey stick graph
The term 'hockey stick' was coined by Jerry Mahlman of NOAA, to describe a graph that is averagely flat to 1900 and then shoots upwards. The flat part is the stick and the upturn part is the blade. A version of the graph referred to as 'the' hockey stick is reproduced below, a graph of data from Mann et al. 1999.
Millennial Northern Hemisphere (NH) temperature reconstruction (blue) and instrumental data (red) from AD 1000 to 1999, adapted from Mann et al. (1999).
Please see copyright notice at foot of this article.
This is of course a northern hemisphere only graph. I concede that point.
'The' hockey stick graph - in fact just one of very many having a similar profile - shows a sharp upward trend in temperatures post 1900. If the graph is a valid portrayal of the scientific data then we are in a heap of trouble if we continue our 'business as usual' use of energy from fossil fuels.
The broken hockey stick
A recent video on youtube has become fairly viral. It purports to show graphs from NOAA which prove conclusively that the 'hockey stick' - the famous graph that shows ever-rising CO2 and temperatures - is fake. It even cites sources, two of which are links to NOAA.
The video is quite blurry and it is difficult to make out the figures in the graphs. The video, by implication, suggests that the video maker somehow got these graphs from NOAA. By a further implication, NOAA itself failed in its duty by not publishing graphs which 'prove' the great global warming swindle'.
In fact, the graphs were created from freely available NOAA data seemingly by or for J Storrs Hall of foresight.org
I'm not going to embed the video, but here is the link:
youtube.com/watch?v=9-B77WMFpxk
If you watch the video or examine the graphs on foresight.org you will see no evidence of a sharp upturn in temperatures. This is being cited by some as 'proof' that global warming is a myth.
The video was created by or for peopleforfreedom.com, a conspiracy theorist's wet dream website which is anti: Freemasons, Global Elite, Illuminati, Medical Mafia, Occult, Paganism, Pineal Gland, Secret Socieites (sic) and anti-just-about-everything. I may have omitted to mention that they are pro "9/11 truthers". Oh, yes. They think that global warming is a myth invented by some power hungry agendist group as a secret conspiracy.
Is it plausible that the published graphs do not show the upturn in the IPCC hockey stick graph?
Hmmmm? Let me think.
The graphs from foresight.org 'prove' that the hockey stick has no blade.
Well, it wouldn't have a blade would it. Would it? Could it?
The genuine IPCC graph reproduced above includes a plot of data from 1902 to 1999.
The graphs used to dispute global warming rely on data that stops before the year 1900.
These people are trying to sell a broken hockey stick all wrapped up to look like a smoking gun.
Discussion:
How real is global warming / climate change?
Andrew Dessler and colleagues from Texas A&M University in College Station confirmed that the heat-amplifying effect of water vapor is potent enough to double the climate warming caused by increased levels of carbon dioxide in the atmosphere.
[my emphasis]
http://www.nasa.gov/topics/earth/features/vapor_warming.html
Every ice front in the southern part of the Antarctic Peninsula has been retreating overall from 1947 to 2009, according to the USGS, with the most dramatic changes occurring since 1990. Previously documented evidence indicates that the majority of ice fronts on the entire Peninsula have also retreated during the late 20th century and into the early 21st century.
Ice Shelves Retreating In Antarctic Peninsula
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Credits:
A big thank you to Aitch from puppy linux forums for bringing some of these materials to my attention.
-------------------------------------------------------------------------------
Copyright notice.
The graph reproduced here is from:
IPCC Third Assessment Report
Climate Change 2001:
Working Group I: The Scientific Basis
Chapter 2. Observed Climate Variability and Change.
Figure 2.20: Millennial Northern Hemisphere (NH) temperature reconstruction (blue) and instrumental data (red) from AD 1000 to 1999, adapted from Mann et al. (1999). Smoother version of NH series (black), linear trend from AD 1000 to 1850 (purple-dashed) and two standard error limits (grey shaded) are shown.
The graph reproduced here is being used in full compliance with the copyright holder's terms of use as stated here:
UNEP/GRID-Arendal grants permission to Users to visit the Site and
to download and copy the information, documents and materials
(collectively, “Materials”) from the Site, under the following
condition:- UNEP/GRID-Arendal is clearly credited in such use of the Materials as the source of the Materials.
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