The most important tool in global warming research is...

Commentor Hoo and I have been going back and forth about the observation made by the Met Office in England (a climate science center) that there really hasn't been any global warming over the past 16 years, despite large increases in atmospheric CO2.

Hoo says there has been substantial warming, almost certainly:

No, it did not stop warming. If you followed troy's link and played with the data yourself (or merely looked up the results elsewhere) then you would know that over the last 16 years the global temperature anomaly increased by 0.13 degrees plus or minus 0.13 degrees (Celsius) per decade.

What does this result mean? Statistically speaking (I know it is Greek for you), it means that the most likely value of the increase was 0.13 degrees per decade. The quoted uncertainty of 0.13 degrees per decade is two standard deviations. In plain English, the rise was between 0.065 and 0.195 degrees per decade with the probability of 68 percent, and between 0 and 0.26 degrees with the probability of 95 percent. The chance that the temperature did not increase or went down is 2.2 percent.

Let me repeat that. 2.2 percent chance that the temperature did not rise or went down.
97.8 percent chance that the temperature did rise.
68 percent chance that it rose between 0.065 and 0.195 degrees per decade.

If I were a betting man, I would not bet against global warming. If you do so then you are a fool.

2.2 percent chance that the temperature anomaly did not rise or went down.
97.8 percent chance that the temperature anomaly rose.
68 percent chance that it rose between 0.065 and 0.195 degrees per decade.

2.2 percent chance that the temperature anomaly did not rise or went down.
97.8 percent chance that the temperature anomaly rose.
68 percent chance that it rose between 0.065 and 0.195 degrees per decade.

I also calculated the trend for the period 1995 to 2009.This trend (0.12C per decade) is positive, but not significant at the 95% significance level. The positive trend is quite close to the significance level. Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods.
Let me unpack this for you. He is saying that the data he uses (HADCRUT) does not show a warming trend with a 95-percent confidence level, but only just so. He is not saying that there is no warming.

Go to the calculator page and select the data set he mentions: HADCRUT4 (put out jointly by the Met Office and Jones). Put the start date at 1995 and end date at 2009. Hit Calculate. You will see a rising trend with a warming of 0.140±0.164 °C/decade (2σ error bars). With a 95 percent confidence the temperature trend was between −0.02 and +0.30 degree per decade. It isn't much different from the trend seen in the GISTEMP data set I quoted earlier.

Furthermore, the line about the last 16 years is a significant distortion. It is statistically much more likely (50-to-1 odds) that global temperatures have been rising over the last 16 years than falling. The positive trend, reported by several different groups, is 1.2 degrees per century, in agreement with the rise in the last 100 years.

One more time, for those who are slow on the intake.

2.2 percent chance that the temperature anomaly did not rise or went down.
97.8 percent chance that the temperature anomaly rose.
68 percent chance that it rose between 0.065 and 0.195 degrees per decade.

Pretty impressive statistics, them.

So what does the data really look like, graphed out?

Here:

Mean global temperature 1997-2012, from Met Office, U.K. 

According to global warming mavens, it shows:

"It is statistically much more likely (50-to-1 odds) that global temperatures have been rising over the last 16 years than falling. The positive trend, reported by several different groups, is 1.2 degrees per century, in agreement with the rise in the last 100 years. [There is a] 97.8 percent chance that the temperature anomaly rose... You will see a rising trend with a warming of 0.140±0.164 °C/decade (2σ error bars). With a 95 percent confidence the temperature trend was between −0.02 and +0.30 degree per decade."

:-/


The most important tool in global warming research is a shovel.