Random Slope Charts – HadCrut

I’ll put these charts up without much comment. I updated them, so I thought I’d post them. Each one represents the historical slope values for the different trend line lenghts (60, 120, …, 360). I just find it interesting to see how the best-fit trend lines adjust over time and compare where we’re at now to historical values.

60-hc-slopes-history

120-hc-slopes-history

180-hc-slopes-history

240-hc-slopes-history

300-hc-slopes-history

360-hc-slopes-history

Temperature Trends for the last 360 months – HadCrut

Here are the latest charts for the HadCrut Global Temperature Anomalies, for the 30 year period ending March 2012.

The Data

What is presented here is the trend over the last 360 months, the slope of which has been in consistent decline over the last eight years. The current slope itself is +.1279. This puts the longer-term trendline of 30 years at a higher slope level than the 20 or 25 year magnitude. If one were to extrapolate this value forward as an expectation of continued warming, it would represent a 1.53 Celsius temperature increase per century. This spurred the question to me as to what starting point in time to current represents the highest current slope. The answer to that is using a starting point of January 1974 (37 years, 3 months), which has a current slope value of 0.13735. Cherry-picking that data point would indicate warming at a rate of 1.65 degrees Celsius per Century. All trend lines shorter than that (starting at least 4 months ago) or longer than than have a smaller slope value.

Chart below:

Trend Line over Last 360 months – HadCrut

The next chart is simply a point of comparison. The highest slope value in recent years occurred with the 30-year period ending December 2003, at the height of global warming hysteria.

Peak 360 Month Trend Line

Finally, I show what has transpired with the slopes in recent years with the 30 year trend line. There has been a consistent decline in the slopes since November 2003 of the best-fitted lines. The decline itself is a very close linear fit though not quite as tight as some of the previous charts. There are periods of deceleration and acceleration in the trend, and even some periods where the slope value increases a bit for a time. Similar to the 25-year chart, in the most recent few months you can see it accelerate in its declining value. There is little indication that this decline will halt in the near term. I should explain how I arrive at that statement. I have a spreadsheet set up to emulate future periods, so by simply typing in prospective anomaly values, I can see what the level of the number needs to be in order to put an end to the declining slope values.

By way of exercise, here are the anomaly values needed to keep the slope the same from the current value to some period in the near future:
1) For the slope to remain level as of April 2012 month end, the next anomaly value has to be 52.
2) For the slope to remain level from April to May, the May anomaly needs to be 51.
3) For the slope to remain level from May to June, the June anomaly needs to be 60.
4) For the slope to remain level from June to July, the July anomaly needs to be 57.

None of these values are impossible. However, given the fact that last 20 anomaly readings are under 50, it would seem unlikely to expect such a series of values suddenly emerge.

Trend in recent 360-month slopes

Temperature Trends for the last 300 months – HadCrut

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

Temperature Trends for the last 240 months – HadCrut

Here are the latest charts for the HadCrut Global Temperature Anomalies, for the 20 year period ending March 2012.

The Data

What is presented here is the trend over the last 240 months, the slope of which has been in very consistent decline over the last eight years. The current slope itself is +.1228. Sp, at this point, the 20-year trend is still positive, even though the last 15 year trend line is slightly negative. This is due to the first five years of the period (1992-97) exhibiting lower anomalies than current averages. That said, the current slope is the lowest value for a 20 year trend line fitted since the period ending June 1998.

Chart below:

Trend Line over Last 240 months – HadCrut

The next chart is simply a point of comparison. The highest slope value in recent years occurred with the 20-year period ending June 2004.

Peak 240 Month Trend Line

Finally, I show what has transpired with the slopes over the last number of years with the 20 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. There is little indication that this decline will halt in the near term. If I plug the latest 12-month average anomalies into each of the next 6 months, we see this trend line dipping below the 0.10 mark in 6-7 months.

Trend in recent 240-month slopes

Temperature Trends for the last 180 months – HadCrut

Here are the latest charts for the HadCrut Global Temperature Anomalies, for the 15 year period ending March 2012.

The Data

What is presented here is the trend over the last 180 months, the slope of which has been in very consistent decline over the last five years. The current slope itself is -.0106, and it is the second month in which the trend line is negative. The current slope is the lowest value for a 15 year trend line fitted since February 1977 (back when people were concerned about another ice age).

Chart below:

Trend Line over Last 180 months – HadCrut

The next chart is simply a point of comparison. The highest slope value in recent years occurred with the 15-year period ending February 2007.

Peak 180 Month Trend Line

Finally, I show what has transpired with the slopes over the last number of years with the 15 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. There is little indication that this decline will halt in the near term. If I plug the latest 12-month average anomalies into each of the next 6 months, we see this trend line dipping below the -0.03 mark.

Trend in recent 180-month slopes