This year saw the second warmest winter in Australia since records began. Across the continent, day and night, average temperatures were 1.33 degrees hotter than the average from 1961 to 1990, the 30-year period meteorologists use as their base.
September was 1.22 degrees above the long-term average. October was more normal, at 0.22 degrees above average. But as our cities and farms sizzle in the heat of November, 2009 is already our eighth hot year in a row.
It's not just in Australia. Monitoring by Britain's Met Office and the Climate Research Unit of the University of East Anglia found that around the world, on land and sea, June, July and September were the third hottest in 160 years of records - August was the second hottest.
And it is not just in 2009. Climate scientists use an 11-year rolling average, more than 4000 days of readings at more than 3000 stations, to judge whether the climate is changing. Over the 11 years to 2008, the average global temperature was 0.41 degrees higher than in the 1961-90 base period, and 0.83 degrees warmer than 100 years ago.
The earth is getting hotter. We can tackle it, or we can ignore it. It is not going away.
We all know that the mainstream of climate scientists believe the main cause is that we have pumped so much carbon dioxide and other greenhouse gases into the atmosphere that they are trapping the heat here - and that to halt the warming, we need to cut those emissions to half current levels.
That's doable. It's just expensive, especially for developing countries.
What if they're wrong?
Well, if we act on the experts' advice and it turns out they were wrong, then we've spent money we didn't need to, as we did on the Y2K scare. But if we don't act, and it turns out they were right, then we risk all the consequences they warned us about: the rising sea levels, the drying out of rural Australia, the increased frequency of extreme events, the flooding of low-lying lands such as Bangladesh, Shanghai, Manhattan, Albert Park and some Pacific islands.
Which risk should we choose? Half the Coalition MPs reportedly want us to take the second option. Malcolm Turnbull, Kevin Rudd, John Howard, Bob Brown - and, the polls find, the vast majority of Australians - want us to take the first.
But deciding to tackle climate change is just the start. How to tackle it is more tricky. There are 1000 options, expensive and effective at one end, inexpensive and ineffective at the other. And all of them are complicated by the fact that climate change is a global problem that must be tackled by national governments - each of which has a common interest in leaving the heavy lifting to others.
It is no surprise that the G20 leaders concluded at the weekend that the goal of finalising a climate change agreement in Copenhagen next month is now out of reach. The goal was always ambitious, the timetable more so. The Doha round trade negotiations are much easier, and they have been going for eight years with no agreement in sight.
Danish Prime Minister Lars Lokke Rasmussen told the G20 he hoped the 191 leaders invited to Copenhagen could still make ''a political binding agreement with specific commitment . . . Not a political declaration with niceties, but precise language of a comprehensive political agreement covering all aspects of the Bali mandates.''
This would see:
- Developing countries commit to actions to slow the growth of their emissions.
- Developed countries commit to reduce their emissions, and help pay the bill for actions taken by developing countries.
- All countries commit to transparent rules to measure, report and verify emissions.
In real life, 191 nations can't negotiate an agreement. Prime Minister Kevin Rudd hints that Singapore might have been a scene-setter, with the real action to take place in Beijing this week when President Barack Obama calls in on President Hu Jintao on his way home. There will be no agreement without the US and China, so the rest of the world would probably have to accept any deal they make.
But it's not clear that there will be a deal, or that Obama could get it through a dysfunctional Congress, or that all 191 nations would agree to be bound to it. As Ross Garnaut explained in his report last year, on this issue, the incentives for policymakers all point them towards offering as little as possible, and trying to shift the burden of action to others. That sums up what has happened in two years of negotiations so far, and it could go on for quite a while yet.
Then why is it important what Australia does? Because climate change can only be stopped by a global agreement, and the example we set will influence - one way or another - what other countries do.
Australia is a rich country, which can afford the cost of reducing its emissions. It is the biggest per capita emitter of greenhouse gases in the G20, and one of the biggest in the world. If our Parliament cannot summon the strength of purpose to tackle climate change effectively, why should developing countries agree to actions that could hurt their more fragile economies and political systems?
That's what leadership is. But as the Coalition parties have shown, no leader can lead when his party refuses to follow. It is time for responsibility, not self-indulgence.