Gadget by The Blog Doctor.

Thursday, January 7, 2010

Fielding's Folly

In a previous post called the Biggest Control Knob I discussed the long term relationship between carbon dioxide (CO2) level and temperature. That post was based on a talk given by Professor Richard Alley, and concluded with a quote from Alley summarising the talk: "an increasing body of science indicates that CO2 has been the most important controller of Earth's climate." That post delt with the issue of CO2 and temperature over very long time frames, it started almost 4 billion years ago and finished at the end of the last ice age, 10,000 years ago.

This post deals with the issue of CO2 and temperature over short time periods, ie the last century or so.

An Australian Senator, Stephen Fielding, the lone Senator for the Family First Party, has tried to make CO2 and temperature an issue.

At this link Senator Stephen Fielding presents the graph below:

Fielding makes the claim that "global temperatures have remained steady over the last 10-15 years despite skyrocketing man made carbon emissions."

Does the evidence support Fielding's contention that CO2 increase does not lead to a rise in termperatured?

This post uses graphs from a post at this link. I am hoping to improve my statistical charting skills so that I can down load the data and chart it myself. The website is run by D Kelly O’Day and is well worth a visit.

O'Day generated a chart that shows the CO2 tempeature relationship over a longer period of time, from 1880 to the present day. This chart is shown below and gives a very different perspective on the issue. Clearly the temperature fluctuated but shows a clear upward trend, and CO2 also shows a clearly rising trend.

There is a problem with both of these graphs - the double Y-axis with CO2 on one side and temperature on the other. The fundamental problem with a double Y-axis graph is determining the appropriate scaling of the graph. If the graph designer stretches the CO2 scale and compresses the temperature scale it would appear that CO2 would rise and temperature would stay steady, and if the designer stretches the temperature scale and compresses the CO2 scale it would appear that temperature rises much faster than CO2. That is, you can "prove" anything that you like just by adjusting the two different y-axes.

A better technique is a chart with CO2 on the X-axis and temperature on the y-axis.

Here is O'Day's chart using this technique:

Although there is some scatter in the points plotted, the relationship is very clear - rising CO2 correlates well with rising temperature. The scatter is largely caused by the year on year variations in the termperature record.

So the Biggest Control Knob demonstrated that CO2 was the most important controller of temperture in very long time-spans, and this post has demonstrated that CO2 is a very important element in the current temperature rise.

Unfortunately there are a large number of people out there who are intent on confusing most people on this issue, by presenting distorted arguments and distorted graphs. Unforutnately, Senator Stephen Fielding seems to be one of that group.

In October 2012 John Nielsen-Gammon did an analysis of the claim that Temperature change does not reflect the Co2 change. His conclusion is: ": there’s nothing in recent global temperatures that disproves the importance of CO2 as an agent for climate change." Read his article here.

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