Digital Diatribes

A presentation of data on climate and other stuff

October 2008 Update on Global Temperature – HadCrut

Posted by The Diatribe Guy on October 24, 2008

Trying to catch up here… I’m finally getting around to posting on the HadCrut-released September anomaly, which was 0.3760 (in terms of degrees Celsius, or 37.60 in terms of 0.01 degrees). I’m pleased to announce that I have managed to find the source of the problem from last month’s attempt at upgrading the projection model. There was a silly, yet hard-to-detect formula error in one section of data that shot the whole works.

The information is found here, in column 2..

The September anomaly is 0.3760, as noted above.

*It is 0.0360 degrees cooler than September 2007
*It is 0.0090 degrees cooler than August 2008
*It is the coolest September anomaly since 2000
*The furthest back we can go to find an anomaly at least as large is January 1983. There are no anomalies previous to that where the value is at least 0.3760.

*10th warmest (150th coolest) September anomaly out of 159 data points since 1850
*90th warmest (1,816th coolest) anomaly out of the total 1,905 monthly observations
*More recently, 8 of the previous 12 anomalies were cooler than the September 2008 reading.

*The latest 12-month average is now 29.7, which is the coolest 12-month stretch since the period ending April 2001.

*This month was cooler than previous year, after an increase in each of the last two months

Now for the charts. I provide, as always, the most updated long-term chart as well as the current longest non-warming stretch. I will then present a few selected charts for discussion points and provide my nifty little projection chart, which is for no purpose other than some entertainment.

Overall Trend

The overall trend since January 1850 has a slope of 0.000364, which corresponds to warming of 0.437 degrees Celsius per Century. Light blue lines are raw anomalies, and the black line is a 12-month smoothed number.

Non-Warming Trend

The current period for which we show no warming can be taken back to April 1997, or 11 years and 6 months. The last time we had a stretch this long in the data with no warming was the period ending June 1967.

I chose not to present any 60-month charts this time around, since they are my usual focus. But the data on the current trend line is that it has a slope of -0.2873. This has become slightly less negative now for three consecutive months, and projections suggest that this will continue through April 2009. At that point, we can expect another downturn in the trend.

120-month HadCrut Trend

The 120-month slope is 0.0605, down from last month. Last month was the peak of over a year of increasing slope values. We should see the slope value bounce up and down around this value through next May, at which point it is expected to decline, and becoming negative in January 2010.

120-month slopes trended from HadCrut data

The 120-month slopes have trended down significantly since 2002. The peak value was a slope of 0.3316. We can see that the slopes in recent months ticked back up a bit, as explained in the previous chart.

180-month trend peak from HadCrut data

The 180-month trend most recently saw a peak value for the period ending February 2007. The slope of the trend line was 0.2349. That chart is presented here.

180-month slopes trended from HadCrut data

From that peak, the 180-month slopes have trended down since that time to a slope value of 0.1351, over a 40% reduction in the rate of warming. The slopes are charted here and shows the steadiness of the recent decline in the trend line. The current slope is at its lowest point since the period ending January 1998. In another year, it is expected to decline to 0.0910

240-month HadCrut Trend

The 240-month slope is 0.1534, continuing a trend down in slope values since 2004. That chart is below.

240-month slopes trended from HadCrut data

The 240-month slopes have trended down and are shown here. The peak value was a slope of 0.1967, but is now at the lowest value since the period ending November 2001. Projected slope a year from now = 0.1462.

300-month slopes over time from HadCrut data

The 300-month slopes have cycled over time as shown here. The chart shows that since the early 1920s, there has only been one brief period of negative 25-year slopes from the mid-50s to late 60s. The slope has more or less continued to increase since that time. And despite recent flattening, it is anticipated that the 300-month slope value will continue to increase over the 12 months, from the current value of 0.1581 to a value of 0.1670.

360-month HadCrut Trend

The current 360-month slope is 0.1345, continuing a trend down in slope values since 2003. The current value is the lowest slope since the period ending January 2000.

360-month recent peak trend from HadCrut data

The recent 360-month peak value was a slope of 0.1616 for the period ending December 2003.

Projected HadCrut anomalies.

Just for fun, here is the predicted anomalies from my model for the next few years, based on HadCrut.

And here are the exact figures through 2009:


October 37.37
November 40.51
December 38.25
January 41.98
February 45.16
March 43.42
April 45.64
May 43.26
June 41.07
July 42.39
August 38.86
September 41.87
October 37.68
November 36.35
December 36.22

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