The Global Warming Challenge

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.

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.

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.

After three months of cooling, the global mean temperature anomaly for October was lower than the Climate Bet benchmark 2007 average. Atmospheric carbon dioxide levels have continued to rise.

The last three months have seen a revival of Mr Gore’s hopes of winning the notional Climate Bet, with global mean temperatures more than 0.3 degrees Centigrade warmer than the 30-year average. We’ve seen higher, and lower, temperatures before in the  course of the bet however and, with more than six years to run and with the actual temperature close to Armstrong’s forecast for 25 out of the 43 months to date, the bet is still very much alive.

After five months below the no-change forecast, temperatures have crossed the Al Gore forecast line. See the graph of actual temperature to June 2011 and the history of the bet with Scott Armstrong, to date, in the column on the right. Remember, you can click the graph to get a bigger image for closer inspection.

Global mean temperatures (more correctly, global mean temperature anomalies) for April and May 2011 have been added to our bet chart at top right. After three months at or below the 1981-2010 baseline, April and May were 0.12°C and 0.14°C above the baseline. Temperatures remained below the 2007 mean that Scott Armstrong offered to bet on, however, as they have done since the beginning of 2011. As a consequence, the errors to date from the forecasts that represent the pronouncements of Al Gore and the IPCC are in total 1.8% larger than those from the Armstrong forecasts.

As we have pointed out before, while Armstrong’s bet is based on evidence-based principles and Gore’s is not, 10 years is a short time period for bets about the climate and so the chance of a reversal are not much less than 50%.

We have updated our Climate Bet graph (right) with the latest data from UAH. After 39 months of the bet, Armstrong’s scientific forecast has been more accurate than “Al Gore’s” IPCC forecast for 59% of the forecasts.