The Global Warming Challenge

Evidence-based forecasting for climate change

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Archive for the ‘forecasting’ Category

Global temp warmer than 3°C/century trend for 4th month

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Global mean  temperatures have been warmer than the IPCC/Gore 3°C per century extrapolation for the four months to February 2020. All but one month (May 2019) in the last 14 months has been closer to the IPCC extrapolation than to the Green, Armstrong and Soon (2009) no-trend forecast.

Does that mean that the global warming extrapolation is now ahead in the extended, 20-year, Climate Bet?

No, it does not. The cumulative monthly error from betting on a 3°C-per-century extrapolation from the 2007 annual average temperature anomaly is more than 5% greater than the error from betting on no change.

The relative error of the warming extrapolation is the lowest it has been for 109 months, but it has only been less than 1.0—warming more accurate than no-change—for two months of the 146 months of the extended Bet so far, back in 2010.

Written by admin

March 12th, 2020 at 3:27 pm

Claims 2019 warmest Australian year inconsistent with satellite record

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The UAH global average  temperature anomaly relative to the 1981 to 2010 average was 0.56°C in December, up from 0.55°C the previous month. The 2019 average was the second warmest year in the 12 years of The Bet so far, as is shown by the blue stepped line in the “Whole-Earth Thermometer” chart on the top-right of this page.

While the global anomaly for 2019 was closer to the IPCC-Gore 3°C-per-century warming extrapolation line than to the Green-Armstrong-Soon no-trend forecast, it was below the warming line, as it has remained for all but two of the Bet’s 12 years to date.

The Climate Bet is concerned with the global average temperature anomaly, but local and regional anomalies do not follow in lock step, and sometimes differ markedly. The claim by Australia’s Bureau of Meteorology (BOM) that “2019 was … the warmest … year on record for Australia … since consistent national temperature records began in 1910” is therefore not inconsistent with what was a relatively unremarkable year in the global record.

But how does the BOM’s warmest-on-record claim—based on smattering of “homogenized” land-based readings—stack up against the UAH satellite (lower troposphere) data for Australia?

Not very well, it turns out.

According the UAH data, 2019 was only the fourth warmest year in Australia in the 41 years of the UAH satellite temperature anomaly record. The warmest year in the UAH data was 2017, with an average anomaly of 0.71°C. The figure for 2019 was 0.58°C. The years 2016 and 1998 were also warmer for Australia.

Roy Spencer—one of the researchers behind the UAH data—has provided an analysis of the relationship between claims of anthropogenic global warming and measured temperature, precipitation, and Australian bush fires.

November 2019 sees global temperature above Bet warming line

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With the release of the UAH November 2019 global temperature anomaly, there have been 28 months in which the anomaly equaled or exceeded the 3°C-per-century warming trend line projected from the 2007 Bet base year average. That compares with the 57 months in which the anomaly has been less than or equal to the scientific no-change forecast proposed by Green, Armstrong, and Soon (2009) and the basis of Scott Armstrong’s challenge to Al Gore to bet on forecasts of global temperatures.

Those figures give a sense of how modest the IPCC’s 3°C-per-century warming trend is compared to month-to-month variations over the 143 months (nearly 12 years) of the extended Bet so far. The 28 months of temperature anomalies greater than or equal to the warming trend account for nearly 20% of months, while close to 40% of months have been cooler than the 2007 base year average.

For the latest data, click on the “Whole Earth Thermometer” toward the top right of this page.

Written by admin

December 13th, 2019 at 9:27 am

September 2019 anomaly above IPCC/Gore warming for first time in 2 years

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September recorded the warmest global mean temperature anomaly since October of 2017. If the months of the fourth quarter of 2019 stay on the warmer side, 2019 could be the fourth year in twelve in which the annual average global temperature anomaly has been closer to a 3°C-per-century warming trend than to no-change. For the updated chart of progress of the Climate Bet, click on the Whole Earth Thermometer image on the top right of the screen.

Written by Heidi Mercer

October 12th, 2019 at 10:52 am

March quarter 2019 temperatures warmer than 2018

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The UAH lower troposphere temperature global average anomalies for the first three months of 2019 have been higher than at any stage during 2018 to the extent that they were slightly closer to the 3°C-per-century warming projection from the IPCC than they were to the no-change (no-trend) forecast. By contrast, every month of 2018 was closer to the no-trend forecast. Over the 135 month term to-date of the extended Climate Bet, the global average temperature has been closer to the no-change forecast than to the IPCC “dangerous warming” forecast for more than 70% of months.

Written by admin

April 12th, 2019 at 11:51 am

A warmer start to 2019 sees January a winning month for Mr Gore

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At 0.37°C, the January 2019 anomaly was the highest since since December 2017. Just above the mid-point between the no-change from the 2007 average forecast of 0.159°C and the IPCC/Gore 3°C-per-century “dangerous” warming forecast for January of 0.505°C, the month counts as a win for Mr Gore.

So far, the monthly wins tally stands at:

dangerous warming trend: 40 months
no trend (Armstrong):         93 months.

Over the course of the Bet to date, the dangerous warming forecast has never been the better forecast for as many as 40% of months. The no-trend, no need for policy action, forecast remains the best bet, having won just under 70% of months so far.

Written by admin

February 12th, 2019 at 2:10 am

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 theclimatebet.com site.

Written by admin

January 7th, 2019 at 2:10 pm

November 2018 temperature data, and the UAH trend

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The November lower troposphere global temperature anomaly from the University of Alabama at Huntsville (UAH) team is just out, is little different from recent months, and remains close to the 2007 average that is the base-year of The Climate Bet.

The UAH series now covers nearly 40 years of monthly observations. Over that time, the change in the global average temperature from month to month has been quite small: the absolute change has averaged a little less than 0.1°C, with half warmer than the previous month, and half cooler.

Despite the obvious up-and-down nature of the series, some commentators continue to look for evidence of a trend hiding in the noise of monthly and annual volatility. For example the IPCC’s, business as usual 3°C-per-Century should be evident in 40 years of data if it amounted to a real trend.

Followers of the IPCC would presumably be pleasantly surprised, then, to learn that the trend to date amounts to little more than 0.001°C-per-month; less than 1.3°C-per-Century. In other words, from month-to-month the typical up or down change is in the order of a 100 times larger than the “trend.”

If the well-hidden trend happened to continue for a further 60 years, we should be reassured that it is much closer to the no-change forecast than to the dangerous warming scenario. There continues to be neither reason to worry, nor reason for governments to implement expensive programmes and regulations.

For the updated “Whole-Earth Thermometer” reading, click on the small chart to the top right of the page for a more detailed image.

Written by admin

December 5th, 2018 at 2:35 pm

September 2018 temperatures drift lower

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The UAH temperature anomaly for September was for the first time since July 2015 lower than the 2007 base year average that is the basis for the Climate Bet. With that latest dip in the global mean temperature, 42% of the 129 months of the extended bet period have seen temperatures lower than the base year average, which is also the no-change forecast proposed for the “Bet” by Professor Armstrong.

To put the 42% figure into context, consider that over a long period of time one would expect the actual temperature to be lower than an unbiased forecast about half of the time, and above it half of the time. While 42% is not 50%, contrast the figure with the percentage of months for which the actual temperature was greater than the Gore/IPCC global warming extrapolation of 0.3°C per decade… that figure is less than 19%.

With 111 months of the second decade of the bet remaining, the actual temperature would need to be below the 2007 average for 59.4% of months for the no-change forecasts to be counted as “perfectly” unbiased. For the dangerous warming forecast to be considered “perfectly” unbiased, actual temperatures would need to fall above the 0.3°C per decade trend line for 86.4% of months.

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October 6th, 2018 at 3:04 pm

Science, and forecasting climate

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Scott Armstrong presented a paper at the International Symposium on Forecasting in Boulder, CO, on 19 June titled “Do Forecasters of Dangerous Manmade Global Warming Follow the Science?”. A pdf copy of the slides is available from ResearchGate, here.

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July 5th, 2018 at 12:50 pm