The Global Warming Challenge

The May 2013 data has been released and shows the monthly temperature anomaly was below the 2007 average that is the starting point of the Armstrong-Gore graph for the fourth month running. So far, the total error of Mr Gore’s warming forecast is 21% larger than the error of Professor Armstrong’s no-change forecast. See the updated Climate Bet graph at right for the details.

It occurred to us that the bet would have been fairer to Mr Gore and the IPCC if we had used the data that were available to Mr Gore when he released his movie “An Inconvenient Truth”, during 2006, as the base-year for The Bet. (The base year that we use for The Bet, 2007, was the most recent data available when Professor Armstrong issued his challenge to Mr Gore.) And so we re-ran The Bet using the 2005 average (the latest full year available to Mr Gore when he released his movie) as the base year. Mr Gore’s forecast in the re-run is for a 0.03ºC p.a. increase from the 2005 average and Professor Armstrong’s is simply the 2005 average.

In the event, re-running The Bet from 2008 to date using 2005 as a base results in a total error for the Gore/IPCC alarming warming forecast that is 31% larger than the error of the no-change forecast. We think Mr Gore would likely prefer to stick with the current Bet arrangement, even though it is not as fair.

After spiking in January, temperatures in April were again well below the 2007 average that is Scott Armstrong’s forecast. (See the updated chart to the right for the state of the bet.) Over the duration of the 64 months to date of the bet, temperatures have been greater than Mr Gore’s IPCC-based warming forecast for 15 months or less than 23% of the time. In contrast, temperatures have been less than Professor Armstrong’s evidence-based forecasts for 36 months or more than 56% of the time. None of the forecasts was exactly equal to the actual temperature. The results support the contention that Mr Gore and the IPCC’s dangerous warming forecasts are insufficiently conservative given the state of knowledge about climate, and that the Green, Armstrong, and Soon (2009) no-change model provides a better representation of the considerable uncertainty that exists.

The latest, March 2013, global mean temperature data from UAH is now plotted on the Climate Bet Graph at right. The temperature anomaly was the same as it was in February and was again cooler than Scott Armstrong’s no-change forecast. Overall, Al Gore’s IPCC “bet” of warming of 0.03°C per annum has been 18% less accurate than the no-change forecast. Over the 63-month life of the bet to date, on the basis of cumulative absolute error, Al Gore’s alarmist forecast has been the better bet for the 8 month period ending January 2011 only.

Bob Carter, Willie Soon, and William Briggs describe the evidence that changes in radiation from the Sun are the major source of changes in the Earth’s climate in a new article in Quadrant. The claim may seem uncontroversial, but global warming alarmists argue that human emissions of carbon dioxide have such a big effect that they dominate solar changes and are inexorably and dangerously boosting global mean temperatures. The Climate Bet is a test of these hypotheses, with Scott Armstrong “betting” on unpredictable changes in solar radiation and Al Gore on CO2-induced warming… and you know how that has been going.

As we’ve written before, trends appear to emerge in the data, then reverse, on all timescales. January 2013′s relative warmth turned out to be a one-month spike, with temperatures in February again below the 2007 global average temperature. Since the first month of Scott Armstrong’s “bet” with Al Gore, the UAH monthly temperature anomaly has been cooler than the 2007 average for 34 out of the 62 months. In other words, to date 55% of months have been cooler

A jump in global mean temperatures of 0.3°C from December 2012 to January 2013 has helped to keep the bet alive as it enters the second lustrum of its 10-year term. To date, Professor Armstrong’s naive forecast has been more accurate for 40 months out of 61 and has been nearly 13% more accurate overall.

Of the first 60 months of the 120 month (10 year) Climate Bet, Scott Armstrong’s naive model forecast* of no change in global average temperatures has been closer to the actual temperature than Al Gore’s IPCC-orignated 3°C per century warming forecast for 40 months. The updated Climate Bet Graph is to the right.

Mr Gore and much of the media are concerned about global warming. They should be relieved to learn that over the last five years (2008 to 2012) temperatures were flat or down from the previous month for 62% of months. The year 2012 ended with the global mean temperature for December the same as for the base year for the bet, 2007.

We calculate from the Hadley Center’s global average annual temperature estimates from 1850 to 2012 that the next five years would have to witness a rate of annual average temperature increase greater than 78% of previous five-year sequences in order for Mr Gore to win the bet. Perhaps, like the UK Met Office, he would like to reconsider his forecast.

*To learn more about the naive model, and the performance of no-change forecasts compared to the IPCC’s “forecasts”, see these papers:

Green, K. C., Armstrong, J. S., & Soon, W. (2009). Validity of climate change forecasting for public policy decision making. International Journal of Forecasting, 25, 826–832.

Green, K. C., Soon, W., & Armstrong, J. S. (2013). Evidence-based forecasting for climate change. [Working paper - not for citation].

November 2012 global mean temperature data from the University of Alabama at Huntsville is out. The chart to the right displays the up-to-date figures. After 11 straight months of temperatures closer to Armstrong’s no-change forecast, in September and October temps were closer to Mr Gore’s IPCC-warming forecast. The brief warm spell didn’t last, however, and the global mean temperature in November is once again closer to no-change than to alarming.

With only two months to go until the half-way point of Scott Armstrong’s notional bet with Al Gore, it is impossible for Mr Gore to take the half-time lead. He would have to be perfectly accurate for the next two months, as well as have been perfectly accurate for the six just gone in order to do so. The latest chart showing the progress of the bet to October 2012 is to the right. Click on it for a larger image.

Adjustments to allow for a drifting satellite have found UAH temperatures to be flatter than previously estimated. As a consequence, Armstrong’s bet is safer than before. Gore’s forecast errors to date are 16% larger than the errors from Armstrong’s no-change forecast, and the no-change forecast of global mean temperatures has so far been more accurate than the Gore/IPCC forecast for 67% of the months covered by the bet. For the latest month (September 2012) and revised series, see the updated chart in the right column.