Digital Diatribes

A presentation of data on climate and other stuff

November 2008 Update on Global Temperature – HadCrut

Posted by The Diatribe Guy on December 3, 2008

Just to clarify, this is the update using October month-end information. HadCrut has not released the November anomaly yet, and probably won’t for a couple weeks. I just fell behind last month and wasn’t able to get to this as timely as I would have liked. So, here is the update with some randomly selected charts. (I really did choose them randomly. I’m such a geek)

The information is found here, in column 2..

The October anomaly is 0.440.

*It is 0.073 degrees warmer than October 2007
*It is 0.069 degrees warmer than September 2008

*6th warmest (154th coolest) October anomaly out of 159 data points since 1850
*63rd warmest (1,844th coolest) anomaly out of the total 1,906 monthly observations

*The latest 12-month average is now 30.3, which is a slight increase from last month’s recent low point. The 12-month average has been in the range of 29.7 to 30.4 for six months running.

*There are no current streaks of consecutive cooler or warmer anomalies over previous year of any significance.


Overall Trend

The overall trend since January 1850 has a slope of 0.000365, 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

60-month HadCrut Peak Slope

The most recent peak in the 60-month slope occurred in the period ending April 2004, and the slope value was 0.5225.

60-month HadCrut Trend

The current 60-month slope value is -0.2596. We can see how the current slope has trended down from the peak in this chart of slopes since January 2004. There is a little curl up in recent months, and that is expected to continue for another 6 months based on a review of anomalies dropping off the front of the 5-year line. But after that, the downward trend is likely to continue.

120-month HadCrut Slope Trend

The 120-month slope is 0.0631, up slightly from last month. This has now reached its highest value since the period ending March 2007. Based on the front-end anomalies dropping off the shifting trend line, this slope value should also continue to increase over the next few months before reversing direction once again. The trend line since 2002 in slope values is negative, however. Should the slopes continue to increase more than a few more months, I'll change this chart to an increasing trend chart. For now, though, given the longer term trend since 2002 and a look at the expected continuation in the negative direction in a few months, I'll maintain the current downward trend chart.

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 trend peak from HadCrut data

The 120-month slopes have cycled up and down over time, as demonstrated by this chart. The last time we had an extended period of positive slopes occurred from 1915 to 1946. The current period (discounting a very brief shallow negative slope that occurred in 1997) started in 1979. We are nearing the zero mark. If this is a reasonably equivalent cycle, then the zero mark could be hit in 2010 or so. The last cycle entered a period of significantly negative slopes.

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 0.1311, 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.

240-month HadCrut Trend

The 240-month peak slope occurred in the period ending April 2004, with a value of 0.1967.

240-month HadCrut Trend

The 240-month slope is 0.1530, continuing a trend down in slope values since 2004. This is the lowest 240-month slope since the period ending October 2001.

240-month slopes trended from HadCrut data

The 240-month slopes have cycled over time and shown in this chart. From 1920 to 1950 there were persistently positive 240-month slopes in the temperature data. The current period of persistently positive slopes began in 1979. Based on the current slope value, there would need to be a fairly significant drop in a short period of time in the slope values to reach zero in 2009 or 2010. While that steep of a drop is probably unlikely, the end of the previous period did, in fact show a pretty steep drop at the end of the cycle.

300-month slopes over time from HadCrut data

The 300-month slope value is currently 0.1582, which continues a recent increase in value. The downward trend in these values hasn't been going on for too long, and the chart is shown here.

360-month HadCrut Slope Trend

The current 360-month slope is 0.1339, continuing a trend down in slope values since 2003. The current value is the lowest slope since the period ending December 1999.

360-month cyclical slope trends

The 360-month slope cycles are shown here. The slope has been persistently positive since 1973. The last cycle of persistently positive slopes extended from 1926 to 1957, so the current period has already extended beyond that length of time. Even a consistent decline at this point will take a while to hit the zero level, so the current period is sure to be quite lengthier than the previous period.

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One Response to “November 2008 Update on Global Temperature – HadCrut”

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