Temperature Trends for the last 300 months – HadCrut
Posted by The Diatribe Guy on May 22, 2012
Here are the latest charts for the HadCrut Global Temperature Anomalies, for the 25 year period ending March 2012.
The Data
What is presented here is the trend over the last 300 months, the slope of which has been in very consistent decline over the last five years. The current slope itself is +.113 (actually a bit less than the 20 year slope). So, at this point, the 25-year trend is still positive
Chart below:
Trend Line over Last 300 months – HadCrut
The next chart is simply a point of comparison. The highest slope value in recent years occurred with the 25-year period ending February 2007.
Peak 300 Month Trend Line
Finally, I show what has transpired with the slopes in recent years with the 25 year trend line. There has been a consistent decline in the slopes of the best-fitted lines. The decline itself is a very close linear fit, though in the most recent periods you can see it accelerate in its declining value. There is little indication that this decline will halt in the near term. If I plug the latest 12-month average anomalies the values continue to decline.
Trend in recent 300-month slopes
Digital Diatribes 
Luke said
“There is little indication that this decline will halt in the near term.” What are the “indications” that you would look at?
The Diatribe Guy said
I have my spreadsheet set up to test go-forward slope values using inputted anomaly values. The anomalies that would be required to halt the downward trend are well above any recent anomaly values. As a point of interest, I could provide those numbers to illustrate. Maybe I’ll do that next post.