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Climate Change: An Inconclusive Truth

Last week Sydney experienced its longest heatwave on record, while Cyclone Yasi attacked the coast of Queensland and record falls of rain continued to flood northern Victoria. Meanwhile 30 states in the US have been impacted by one of the worst snowstorms in the country's history. All this follows one of the planet's warmest years on record (except in Britain where it was one of the coldest) and renewed warnings last week from economist-come-climate change expert Ross Garnaut that "you ain't seen nothin' yet".
So is all this catastrophic weather the result of climate change? Or is it nothing more than cyclical weather patterns, El Nino and La Nina? Frankly, I haven't a clue. It's next to impossible to hear any reasoned debate beyond doomsayers and deniers. Where's the middle ground?

Take opposition leader Tony Abbott's view in October 2009 that the argument for climate change was "absolute crap". It doesn't sound like the response from a man prepared to entertain reasoned debate on the subject.

We all seem keen to jump to one side of the fence on this issue, even if the only research we've done is a trip to the cinema to watch Al Gore's An Inconvenient Truth --- the only Hollywood blockbuster made entirely in PowerPoint. And the problem is, it's easy to extract statistics and use them to support your argument.

The first 10 years of this century, for example, provided 148 very hot days (over 40°C) in Australia, compared to just 114 the previous decade and only 94 days in the '70s. So the trend is towards hotter weather, right? Well, it would be if the '80s hadn't had 127 hot days. All we can say is that the last ten years have had the most, but it doesn't make a trend.

Everyone accepts that there is more carbon in the air. The intergovernmental panel on climate change reckons there's 25 percent more than the natural range of the last two million years --- and 120 percent more methane and 9 percent more nitrous oxide. Keen to see the impact of this on Australia's climate I trawled through the historic data on the Bureau of Meteorology website.

Sure enough, when I graphed the monthly averages for maximum daily temperatures recorded at Sydney's Observatory Hill there is a clear and persistent upwards trend. Basically the Sydney temperature is at least two degrees higher than it was 150 years ago, but is that any surprise? It's a far more densely populated city, filled with congested traffic belting out hot fumes and tall buildings with their air conditioning on overdrive. We see a similar trend from Melbourne (although the increase has been more recent and slightly steeper) and to a lesser extent in our other, smaller, capital cities.

Yet much smaller towns and cities are not seeing the same increase. Oodnadatta, in South Australia, recorded Australia's highest ever temperature (50.7°C) back in 1960. The town has seen temperatures steadily rise since the 1930s, but we don't have the records to know what happened before that. What we do know is that Dubbo has seen a slight increase of late, but the town is still a long way behind the peaks of the late 1890s. In Horsham, in Victoria, there's been no discernable trend upwards.

The Bureau of Meteorology website says since the middle of the 20th century "Australian temperatures have, on average, risen by about 1°C with an increase in the frequency of heatwaves and a decrease in the numbers of frosts and cold days." But how much of this is driven by the impact of heat from bigger cities, rather than increase carbon in the atmosphere?

When it comes to rainfall, I find even less evidence that the Australian climate is changing. There were 616 wet days in the first decade of this century â€"-- making it the driest decade of the last 100 years. It precipitated-it down a lot more in the '70s, when there were 708 wet days. Admittedly 2010 was the wettest, with 5 days of very heavy precipitation (more than 30mm), beating 4.9 days in 1974, 4.6 days in 1950 and 4.3 days in 1956.

Many greater minds than mine have spent many more hours looking into this, but a few hours of rudimentary analysis is enough to convince me that it's not as black and white as both sides would have you believe.

Even if the evidence is hard to uncover, there are other reasons for us to make a swift move to a lower-carbon future:

  1. Climate change might be real. The consequences are too big to ignore.
  2. Fossil fuels can be harmful and destructive. Imagine how many more Gulf of Mexico incidents we could expect as oil companies drill deeper in a need to meet our growing demand for fossil fuels. Go and breathe the air in the NSW Upper Hunter, where the ABC Four Corners documentary last April pointed to higher rates of bronchial disease, raising the question about the impact of open-cast mining and coal-fired power stations on our health.
  3. Peak oil. Many argue we've already reached the point where production will start to decline. In the US production peaked in 1970 and imports are now twice the level of domestic production. Imagine the economic and geopolitical impact of rising oil prices as demand markedly outstrips supply with a trend that will only get worse over time.
Ross Garnaut might win few supporters by jumping on the recent catastrophes with his "you ain't seen nothin' yet" remark (he's clearly a Bachman Turner Overdrive fan), but he is right that (for these three reasons at least) we need to drive behavioural change.

In 2005, Australia chucked out 27.3 tonnes of CO2, compared to 10.7 in the UK and 9.0 in France. We're even ahead of the US (23.4 tonnes). At the risk of touching a nerve, we need a carrot and stick measure, involving some sort of financial penalty for those who persist to use high-carbon fuels. And as we examine alternatives, the other serious question for Australia is around our hesitancy to adopt nuclear energy. It already accounts for 14 percent of the world's electricity. In the US, 104 nuclear reactors create more than 20 percent of all their electricity. Here in Australia, the largest exporter of uranium, we have remained philosophically opposed to the idea.

So, now is the time to raise the level of informed debate â€"-- less "climate change is crap" and more discussion on how we can agree on the extent of the impact, the potential implications and a goal of where we want to get to. Have a look through some of the data and see what conclusions you can draw. I'd love to see your own observations in the comments stream below.

Do your own analysis

See also:

Read more By The Numbers articles by Phil Dobbie here.

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