The Global Warming Challenge

Evidence-based forecasting for climate change

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Archive for the ‘forecasting’ Category

June 2020 temperature anomalies remain warmer

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The UAH global average temperature anomaly for June was down a few points from May, but remained warmer than the 2007 average and closer to the warming than the no-change line. That’s 13 months in a row in Mr Gore’s favor!

Click on the Whole Earth Thermometer chart image to the top right of the page for the figures and a larger chart.

Written by admin

July 4th, 2020 at 6:01 pm

May temperatures jag up as warmer spell continues for 12 straight months

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The UAH global average temperature anomaly (lower troposphere) for May 2020 was again closer to the IPCC-Gore “dangerous” warming projection from the 2007 average than to the Green-Armstrong-Soon forecast of no-change (trend). The absolute error from predicting dangerous warming remains greater than that of the error from no change over the more than 12-years of the Climate Bet so far, however, being 2.6% greater.

The May figure was yet another reversal in the direction of change (“trend”) from one month to the next. That is the norm. Over the now more than 40 years of the UAH temperature series, the correlation between the monthly change in temperature anomaly and the change in the previous month was negative (-0.33). To put it another way, for more than 55% of months, the direction of change from the previous month was the opposite of direction of change a month before.

For the latest chart and data, click on the World Thermometer image toward the top right of the page.

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June 9th, 2020 at 7:27 pm

April 2020 warmish, but coolest since July last year

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April’s anomaly remained above halfway between the no-change—from 2007 annual average—forecast and the IPCC/Gore +3°C per century warming projection, and so with its smaller error counts as a win for the month for the projection.

The recent run of warmer global average temperatures has pushed the cumulative relative absolute error to 1.039—which means that the warming projection’s cumulative absolute error is 3.9% larger than that of the no-change forecast—the lowest it has been since December 2010, 3 years into The Bet.

As a consequence of the run of warmer temperatures, The Bet is more alive now than it has been for about a decade. For example, if the UAH global mean temperature anomaly turns out to be close to the red IPCC/Gore warming line for each of the next three months, the cumulative error from that projection would be smaller that that of the no-change forecast.

See the Whole-Earth Thermometer chart at the top right for the latest figures.

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May 8th, 2020 at 2:43 pm

March 2020 cooler than IPCC/Gore projection for first time since October

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As expected from the history of the series, the UAH global average lower troposphere temperature anomaly declined in March. The decline took the temperature to a level last seen in October.

Why expected? Considering the whole UAH series (496 months less 2), the correlation between the month-to-month change in temperature and the previous month-to-month change (the lagged series) is -0.3322. The negative sign indicating that if the most recent month’s temperature anomaly is up on the previous one, the next month is more likely to be down, and vice versa.

How likely is a reversal of direction between months? The probability is about 0.55, based on the 494 available observations to date.

Finally, the temperature anomaly increased in slightly less than half of 495 months or 49.5%.

To see a large version of The Climate Bet chart and data, click on the Whole Earth Thermometer chart image at the top right of the page.

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April 21st, 2020 at 11:15 am

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.

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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.

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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.

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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