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The Climate Scales In Our Eyes

Dr David Whitehouse, GWPF Science Editor

Our recent graph of the global surface temperature this century (HadCrut4) and carbon dioxide in our atmosphere caused a few comments. This is what we published.

Click on image to enlarge.

A handful of commentators thought this graph was highly misleading. The reasons why they thought so are illuminating. One said that it was inept and an example of “shameless manipulation” of the graph’s Y-axis. To show how it should be done they decreased the Y-axis by about a factor of two, producing this.

Click on image to enlarge.

This obviously restores the balance and shows the relationship between carbon dioxide concentration and global warming!

A factor of about two in a graph axis is really neither here or there, but our original graph was incomplete in that it did not include error bars, as seems almost traditional in climate communication. We have now remedied this and, taking the advice from our critics, we’ve redrawn the graph using the new scale and added the error bars.

Click on image to enlarge.

The problem is that whilst carbon dioxide concentration is increasing monotonically the annual global temperatures between 2001 and 2014 are all within each other’s error bars indicating their statistical equivalence. The global average temperature does go up in 2015 due to a strong El-Nino and at a rate much faster than global warming — only to come down again after the El Nino, thus showing that it is a feature not due to the global warming trend.

Over the years, we have seen numerous theories and explanations for the lack of a manifest warming trend and the increased consideration for decadal variability. But to change the scale of our original graph and claim it shows an obvious 21st century correlation between global temperature and carbon dioxide is simply inept.

Reeling in the Years

We are all used to annual pronouncements that the last year is the 3rd or 4th warmest on record. It generates a lot of media comment. But given the graph showing the annual temperatures and their associated errors should we not revert to what NOAA used to do with their annual temperature ranking when they did not rank the years strongly. Between 2001 and 2014 and since the downturn after the 2015/16 El Nino the scientific way to describe their differences is as not significant. You would not teach in Physics 101 that you quote a measurement of a continuous variable to one part in a thousand when its error is a hundred parts in a thousand, as is the case for HadCrut4. The sensible way is to round the annual global temperature to 0.1 degree C. To rank years swimming about in statistical noise yet hype it as a big media story and a policy driver is nonsense.