In the journal of Planning Institute Australia, Australian Planner, in June last year, there was a sort of retrospective: the journal was devoted to articles that appeared over the past forty years. All were worth reading, because planning is a dynamic trade, and it is instructive to see what concerned people in the recent past. A few of them centred on ‘climatic change’, and they went onto my ‘must read’ basket. Alas, that basket is always full, and it was only over the holiday period that I started to read.
Graeme Pearman was one of the contributors, and in 1987 he was a scientist with the Division of Atmospheric Research in CSIRO. In 1992 he became its Chief, and he served as such until 2002. He is a much awarded scientist, has an international reputation, serves on international committees,and apparently advised Al Gore in the making of the ‘Inconvenient Truth’ film.
In 1987 he wrote on ‘Climatic Change and Coastal Planning’, and his paper is measured and interesting. Apparently scare stories were alive and well then. I wasn’t at all interested in the topic, and it was not, at least in my memory, much discussed in the ARGC, about which I wrote a couple of days ago. Apparently the Age ran a story in 1986 (I haven’t been able to find it) that sea levels were expect to rise by nearly two metres per decade over the next fifty years. Pearman pooh-poohed such exaggeration, but then went on to argue that there was change coming, and that planners should take it into their consideration.
What was the change? Well, greenhouse gases were increasing in their concentration, and that meant that scientists were now predicting discernible climatic change in the next 30-50 years. Models of the climate system were still crude, but the modellers felt that the earth was ‘likely to warm by 1.5 – 4.5C on average’. Dr Pearman was cautious about all this, and wrote, presciently, that ‘the discovery of this trend has influenced the level of conviction of some scientists that the predictions will eventuate’.
What about sea levels? Again, he was cautious. If the world gets warmer, the seas will expand and rise. Perhaps a little of that has already happened. What was in prospect for us in Australia? A generally warmer and wetter climate, with warming in the winter and the increase of rainfall in the summer, was one answer. You could assume, he said, that the warming that has taken place over the last hundred years ‘is a reliable analogue of the changes that will occur’. What should planners do about all this? They should adapt, and recognise that something of this kind is very likely to occur, even if it is not disastrous, and go in for impact assessment studies. There is not a word here about carbon taxes, or the IPCC (which had yet to be created). All told, it is an interesting and cautious account of the state of knowledge at that time.
What has happened since? He was right about increasing levels of greenhouse gases. Carbon dioxide, at 340 parts per million, is now round 390; methane, at around 1590 parts per billion, is now at around 1800. Temperature? It depends on which measure you look at, and how much you trust the precision of the measurements. But on any account, and I prefer the satellite figures, temperature has increased. The usual way of measuring it is via the global temperature anomaly — the average of measurements compared with the average for a baseline period.
The UAH reading for 1987 to 2012, compared to the 1981-2010 baseline, gives a shift from around -0.1 to +0.2. That’s a rise, but not much of one. Given that there has not been much warming for the past 16 years, and that the great spike of 1998 was an el Nino event, it would seem to me that if there is going to be an increase of 1.5 to 4.5C in the 30 to 50 years from 1987 there will need to be some pretty sustained and rapid heating soon, given that 25 years have passed since Dr Pearman wrote his article.
What about sea levels? If you ask Professor Google for help here, you will get over 41 million hits. I don’t myself think we know, or can measure accurately, the extent to which the oceans have risen. Given that ENSO can push half a metre of water across the Pacific, looking to measure sea-level rises, and to assess whether or not they are accelerating or decelerating, seems to me akin to counting the number of angels dancing on a pin. What we can say is that storms, surges and flooding are still with us, and that we need, as Dr Pearman argued in 1987, to treat these phenomena seriously.
He could argue that a lot has happened since 1987, and that we do know a lot more than we did then. I would agree, and argue that we will know even more in another twenty years. The IPCC will be issuing its Fifth Assessment report soon, and it is likely to tell us that things are even worse than they were in 2007, when the Fourth Report came out, though the evidence seems quite equivocal to me.
I remain agnostic.