In a previous post, I showed the Lower Stratospheric Temperature Anomaly (TLS) Trends (link). A reader submitted the following comment:
“The lower stratosphere temperature profile is essentially flat from ca. 1995 to the present. This approximately mirrors the temperature trend for the surface temperature. From 1980 to about 1995, the surface temperature increased while the lower stratospheric temperature decreased. After that both went flat.” tony
In the words of Edwards Deming:
In God we Trust, All Others Must Bring Data”
Since tony didn’t bring any data to back up his claims, I’ll do the analysis for him.
First, here’s the trend chart tony discussed.
- The lower stratosphere temperature profile is essentially flat from ca. 1995 to the present.
- After that  both [TLS & TLT] went flat.
Tony apparently eyeballed his findings after looking at my chart. Eyeballing climate trends is not wise, climate trends usually have a lot of variability that can fool the eyes, regression is a much more effective method.
Assessing Trends: Eyeball versus Regression
tony focused on post 1995, so I’ll chart data after 1995. tony says the TLS and TLT data went flat. I’ll use the 1995 – 2011 (so far) mean to represent the flat trend (green line) and I’ll use a gls regression trend (red) line for the regression based trend. The chart below shows the results for both TLS and TLT:
Let’s see how tony did:
- “The lower stratosphere temperature profile is essentially flat from ca. 1995 to the present. “Wrong – The TLS actually had a slight positive trend of 0.006/year. To be precise, this slope is not significant @ 95%, so tony would have been correct if he said “statistically flat” .
- “After that  both [TLS & TLT] went flat.” Wrong. The TLT had a 0.012/year trend. This slope is statistically significant @95%, so tony has no wiggle room here.
tony got claim 2 completely wrong and a partial credit on claim 1 if he meant to say “statistically flat”.
Deming was right! In God we trust, tony and everyone else must bring data! Eyeballing climate trends is not reliable. While time series regression has problems (link), it is wiser to show a moving average or regression rather than rely on eyeball interpretation of trend lines.
Here is my RClimate script (link) if tony or anyone else wants to check my analysis.