The Global Warming Challenge

Evidence-based forecasting for climate change

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Archive for January, 2019

2018 year ends on a low note, temperature wise

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The UAH global mean temperature anomaly data for December 2018 is out: the figure of 0.25°C.

The average for the year was 0.23°C, with a maximum anomaly of 0.32°C and a minimum of 0.15°C. None of those figure is much different from the 2007 Bet base year average of 0.16°C, and are all well within the base year range of -0.04°C to +0.43°C.

Interestingly, in the now 11 years since 2007, monthly global mean temperature anomalies have fallen outside the 2007 range on only 32 of the 132 months, with nearly half of those months (15) falling below the 2007 minimum.

The 2018 year was cooler than any of the previous three years, and cooler also than 2010. In other words, 2018 was cooler than 40% of the previous ten years.

So how do things stand with the extended “Bet” between the no-change model forecasts and the IPCC’s 3°C-per-century “dangerous” warming projection (standing in for Mr Gore’s “tipping point” warnings)?

After 11 years, the Bet’s summary measure—the cumulative absolute error of the warming projection relative to that of the no-change forecasts—is 1.211. In other words, the errors of the “dangerous” warming projection have been 21.1% larger then the errors of the forecasts from a simple model that assumes that we do not know enough about the causes of climate change to make predictions over policy-relevant horizons that are more accurate than an extrapolation of the previous year’s average into the distant future.

Note also that unbiased forecasts would be expected be warmer than the actual temperature as often as they were cooler. To date, the actual temperature has been equal to or warmer than the IPCC/Gore projection for only 18.2% of months. That figure compares with the 40.9% of months that the temperature anomaly has been less than or equal to no-change projection.

For the latest data and chart summarising the Bet, click on the Whole-Earth Thermometer on the top right of site.

Written by admin

January 7th, 2019 at 2:10 pm