I may just be uninitiated, and am certainly too lazy to read the entire study, but I have to wonder why the graph compares a period of 10 years (2001-2011) to a period of 29 years (1951-1980), and the ommission of the data in between (1980-2001). Is it not more useful to compare the same lengths of time, say, each 10 years?

It seems to me that the graph is comparing “now” (the average of the last 10 years) to a preceding baseline (data up to 1980).

What happened between was, of course, a transition from “then” to “now”, so the intervening data would, in this format, only obfuscate the actual conclusion.

Hansen has been debunked already by his own colleagues.

Citation needed.

Ah, the old Anthony Watts ‘trick’ to ‘hide the incline’: use the most recent baseline that you possibly can get away with, so the warming anomalies are minimised. In fact, if you can use just the current year as the baseline period, all the temperature anomalies are *negative*; therefore, it’s cooling!!!1!!!

ETA: that’s why Watts particularly likes the satellite records. Since they only started much more recently than the land records, they have a more recent baseline period (~1980 – 2010 rather than 1951 – 1980 or 1961 – 1990).

In the paper, they give reasons for taking the period they do. They’re somewhat arbitrary, but not entirely. They also show the average curves by decade and you can see the curves marching to the right with each decade. I think that those are probably just less effective as summaries.

If you click through to the paper cited by Phil you’ll find your answer;

“Reference Period. Although we had multiple reasons for choosing 1951–1980 as a base period to define temperature anomalies, as discussed under Materials and Methods, we must ask: Do our conclusions depend on the chosen base period? Could we just redefine climatology based on the most recent decades, perhaps leading to a conclusion that the only climate change has been a small shift of mean temperature that may be insignificant?
The effect of alternative base periods on the temperature anomaly distribution is shown in Fig. 9. Use of a recent base period alters the appearance of the distribution. Climate variability increased in recent decades, and thus the standard deviation increased. Therefore, if we use the most recent decades as base period, we “divide out” the increased variability. Thus the distribution function using 1981–2010 as the base period (Fig. 9, Right) does not expose the change that has occurred toward increased climate variability.”

I have no qualms about the certainty of the conclusion, just wondering about the method.

Yeah, how could we possibly find this out? If only he published details of the study in some sort of document you could read. And if only Phil had linked to that document.

Hint: Try reading the OP again. See those bits of text that are colored differently? Those are links. Try clicking the one that says “has published research”.

Now comes the tricky part. You want to know what methods were used, and what materials those methods were used on. Where would the nefarious Hansen hid such dangerous information?

I’ll give you another hint: try reading the first sentence of the “Materials and Methods” section, which is near the top of the second column of the first page. I think you will find your answer there.

reason why I ask is it clearly isn’t from the USCRN as a simple crunching of the numbers there indicates Hansen is completely off the mark. Why would Hansen not used this shiny new system that NOAA spent many $$$ to get his data?

I don’t know, maybe because

1. USCRN only covers the continental U.S., while the study is worldwide.

2. USCRN only has 114 stations, while the set Hansen used has about 4000 temperature stations.

3. USCRN is intended to provide 50-year temperature records starting in 2008. It isn’t a historical temperature record, so is entirely useless for this purpose.