"Are global temperatures on a warming trend? It is difficult to be certain about trends when there is so much variation in the data and very high correlation from year to year. We investigate the question using statistical time series methods. Our analysis shows that the upward movement over the last 130-160 years is persistent and not explained by the high correlation, so it is best described as a trend. The warming trend becomes steeper after the mid-1970s, but there is no significant evidence for a break in trend in the late 1990s. Viewed from the perspective of 30 or 50 years ago, the temperatures recorded in most of the last decade lie above the confidence band of forecasts produced by a model that does not allow for a warming trend."
The second thing I should have included were these charts illustrating the long-run temperature datasets analysed in the ANU/Monash study:
On a quick visual inspection, the evidence does appear compelling. Rory goes on to explain his thinking on the subject, which I personally find persuasive:
G'day Chris...Recall that you agreed to run alongside my AFR letter the 1-para summary and chart showing a clear uptrend in global temperatures [Ed: Yes mate, apologies for that oversight!]. Please do so now, if it still suits.
My AFR letter was a frustrated response to Des Moore's repeated and unreasonable refusal to acknowledge the critical fact that there IS a clear uptrend in global temperatures. Whatever its cause(s), "global warming" is an empirical fact - simply look at the charts (above).
DM has complained that I played the man not the ball...In my defence, I felt it would add to the debate - the debate that DM seems determined to dominate via an extraordinary number of letters to editors - for besieged readers to know that DM has been badly wrong on big issues in the past, that being nearly 80 years old he has little to lose if he is wrong, and that the IPE ("Institute for Private Enterprise") seems to be DM and not much else. That is, the IPE is just another citizen with an opinion and facts on which no-one should rely.
Again, official readings over the past century-and-a-half in the US and UK display a clear uptrend in global temperatures since the 1970s. Any serious argument can only be about what caused it.
Good luck to DM and his prolific letter writing but as a prolific newspaper reader I felt annoyed enough 10 days ago (when he expressed the same view for the upteenth time) to write a letter myself...It was not published....Then I submitted much the same letter again on Thursday, a week later, after DM was published saying the same thing yet again.
Rgds,
rory
