An Old Mistake From Christopher Monckton

This is not the most up to date issue, but I found it amusing. Whilst looking through some of Christopher Monckton's Great Pause posts on WUWT, I noticed this, in one of his last articles on the subject - The Pause hangs on by its fingernails.

Early on in the extremely long ramblings we get this quote:

The not necessarily reliable Tom Karl of NOAA and the relentlessly campaigning Gavin Schmidt of NASA held a joint press conference to celebrate the grants their rent-seeking organizations can milk out of their assertion that 2015 was the warmest year since 1880. But they carefully omitted the trend-line from their graph, so I have added it back. It shows the world warming since 1880 at an unexciting two-thirds of a degree per century

Accompanied by this graph showing the Monckton trend-line

Source - Christopher Monckton of Brenchley

Now apart from the question of why you would want to fit a linear trend over data that clearly isn't linear, and the fact that Monckton seems to have a problem understanding what the word trend means, and his curious habit of drawing all trend lines with thick lines and meaningless arrowheads, there's one major problem with his trend line. It's completely false!

Here's what the trend line should look like.

It's much steeper than Monckton's line.

The odd thing is that Monckton gets the figures correct. The trend is 0.67°C / century, which means a complete rise of 0.91°C over the 135 years of the data.

The problem seems to have arisen because NOAA are using the antique Fahrenheit scale, as indicated by the description in the top right of their original graph, saying that 2015 was 1.62°F warmer than the 20th century average. The scale of the graph is in Fahrenheit, but Monckton has added a caption in the top left of his graph saying that the scale is in °C. He's then drawing his trend line, scaled to Centigrade. So his trend shows a line with a rise of 0.91°F, not the actual trend of 0.91°C.

Here's the original NOAA graph showing the correctly labelled temperature scale.

NOAA/NASA Annual Global Analysis for 2015 - Page 5

Here's Monckton's graph with the correct trend line in blue.

Corrected version of graph by Christopher Monckton of Brenchley, showing correct trend line in blue.

This may well be an honest mistake by Monckton - the use of obsolete temperature scales by American institutions can cause confusion like this, but it's convenient that it results in a graph that appears to show less warming. And it doesn't explain why Monckton removes the label from the original NOAA / NASA graph and replaces it with his own incorrect label.