Digital Diatribes

A presentation of data on climate and other stuff

Congratulations, RSS!!! 30 Years of Data (aka: January 2008 Update on Global Temperature – RSS)

Posted by The Diatribe Guy on January 7, 2009

RSS Anomaly released for the month of December has been released. As you can see by the title, this is a milestone for the RSS readings. We seem to like that magical 30 year measure for temperature. Well, now we can add RSS to the sets of temperature measures that give us a 30 year trend. Woo hoo!

The RSS data can be located here.

December’s Data Point in context:

  • The anomaly for December was 0.174 (in terms of degrees Celsius).
  • This reading was 0.078 degrees warmer than December 2007
  • It was 0.047 degrees cooler than November 2008
  • The anomaly ranks as the 117th warmest anomaly of the 360 data points
  • It ranks as the 10th warmest December of the 30 Decembers on record


  • The anomaly reading shows a second consecutive year-over-year warmer anomaly reading, following a stretch of 14 consecutive cooler readings.


  • The 12-month average anomaly is 0.092, which is up a bit from last month’s average, and the recent low point of 0.079 two months ago.

Slopes and Charts

The overall RSS trend over the full 30 years shows overall warming. Let's hear it for 30 years of satellite readings!

The furthest back we can extend a non-warming line is to March 1997 (11 years, 10 months.) With the new data point, we actually extended the front end another month from the previous trend line. So, along with the new endpoint, we added two months to the trend line this time around. , it stayed the same while we added one month to the end. So, could we reach 12 years of no warming next time around? Well, it is possible, but it would require an anomaly of 0.083 or lower. That hasn't happened in 6 months, but prior to that we had six months in a row of anomalies beneath that level. So we'll just have to wait and see what happens.

The current 60-month trend is quite negative (-0.3306), though it has actually increased over the last four months. It is still much lower than a year ago. We can see the trend down in the slopes over time, and the recent bump in the slope.

The current 120-month trend is 0.0874. This has now bounced around over the last 3 months, after a 9-consecutive month run of slope value increases in the 120-month measure.

The peak 120-month trend was much higher than the current slope, at 0.3545. So even despite the recent uptick we can see how this has trended lower. Looking forward, there will still likely be more bouncing around for a few months but then the decline should continue, barring much higher future anomalies.

The cycle of slopes for the 120-month trend lines is shown here. It is a bit clearer here that there has been a longer-term trend down in slopes, despite the last year's uptick. The current uptick looks to be flattening at the moment.

The current 180-month trend is 0.1026, which continues a fairly long-term decline in the 180-month slope values. The current value is the lowest calculated since the period ending July 1997.

The way the 180-month slopes have cycled can be seen here, along with the steepness of the decline relative to recent history. We can get a better look at the current value as it relates to the historical slopes.

The current slope of the 240-month trend line, 0.1677, is also on a downward trend, and is the lowest value since the period ending January 2002. Shown here is the current trend line.

The current slope of the 240-month trend line can be seen in its historical context here. There has been a general decline in slope values since 2003.

The current 300-month trend is 0.1698, and while this measure had been bouncing around in the range between 0.1700 and 0.1716 for a few months, the new slope is the lowest slope since the period ending January 2006. Overall, since early 2007, it has also declined slightly, and the chart of slopes for the 300-month trend lines is shown here.

While temperature anomalies are not dropping precipitiously, we are still seeing lower readings than the last few years, which is both producing negative short-term trend lines and suppressing long-term trend lines. Even if next month doesn’t produce an anomaly that gives us a twelve year non-warming period, we will very likely hit that after the February anomaly. But I am confident that we will hear that a 12-year stretch still doesn’t tell us anything, so do not lose faith.


One Response to “Congratulations, RSS!!! 30 Years of Data (aka: January 2008 Update on Global Temperature – RSS)”

  1. […] Congratulations, RSS!!! 30 Years of Data (aka: January 2008 Update … […]

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