Michael Duffy is a columnist for the Sydney Morning Herald who writes entertaining and thought provoking opinion pieces on a range of topics, including urban planning issues (his blog Urban Jungle is well worth a visit). Michael also co-presents Counterpoint on ABC Radio National.
In both the electronic and print media Duffy has repeatedly questioned anthropogenic global warming. Last Saturday in the Sydney Morning Herald he claimed that
For most of the past seven years... temperatures have actually been on a plateau. For the past year, there's been a sharp cooling. These are facts, not opinion: the major sources of these figures, such as the Hadley Centre in Britain, agree on what has happened, and you can check for yourself by going to their websites.
I took up his invitation, and it confirmed that Duffy is pulling our legs. The Hadley Centre data shows that there has been some levelling-off of temperatures, but at a high level. Temperatures have not fallen in absolute terms; they have remained high. The best estimate temperature anomaly for 2008, so far, is +0.296°C which is lower that the record years of 1998, 2005 and 2007, but higher than most years going back several decades (see the data here).
Duffy's claim is akin to saying on a hot day that is slightly cooler than a record hot day before it that this heralds the end of global warming. He has fixed on a trend at an insignificantly short time scale, and neglected to mention that there is no absolute cooling. Quite to the contrary the 2008 records indicate an enduring warming on the back of a succession of broken records. In this light Duffy's opinion piece is highly misleading and disingenuous.
Another authoritative source for temperature observations is NASA's Goddard Institute for Space Studies. The GISS Global Temperature Trends 2007 Summation notes that 2007 tied with 1998 for second warmest in the period of instrumental data, behind 2005 as the record warmest year. The Summation points out that the 2007 warmth was particularly significant because it took place without the heating effect of the El Niño-La Niña cycle and when solar forcing is at a minimum.