Liberal and Labor, make a call: how much heat can you stand?

Richard Di Natale Adam Bandt
June 11, 2007
From The Age (Aust)

WHAT risk of a plane crashing do you accept before buying a ticket? If it was 85 per cent likely, you'd never fly; 10 per cent, or even 1 per cent, would be too much.

Knowing that a plane might go down isn't enough; we want to know the degree of risk. So it's odd that we are prepared to make decisions about the planet's future without knowing the risk or likelihood of catastrophic consequences if action is taken, or not taken.

It can be hard to cut through the fog of figures about global warming targets: the difference, for example, between a 60 or an 80 per cent cut in emissions, by 2020 or by 2050, is difficult to crystallise.

This confusion is being exploited by both major parties and manufactured debates are played out relentlessly. Labor presents itself as tough on climate change while the Coalition says it puts economics above abstract goals.

But more than anything else, there is one number that really counts. It is the first step on the ladder of climate-change policy — and it is the one to which neither Labor nor the Coalition is willing to give an answer.

Given the science and likely impacts, how hot are we willing to let the planet get? Two degrees, three degrees, four degrees hotter?

And what risk will we accept of exceeding this target?

Temperatures have, already, risen 0.74 degrees above pre-industrial levels and, even if human activity added no more to current greenhouse gas levels, the planet will continue to warm about 1.4 degrees due to lags in the climate system.

The CSIRO last year predicted that, if we exceed a two-degree rise, 97 per cent of the Great Barrier Reef will be bleached annually and an 80 per cent loss of Kakadu's freshwater wetlands is likely. At just under three degrees, there's a 99 per cent risk of Greenland irreversibly melting, with an eventual global sea level rise of five to seven metres.

In the two to three-degree range, we can conservatively pencil in about 20 per cent of the planet's species becoming extinct and a one in five chance of the oceanic currents that regulate the planet's temperature simply shutting down.

A three-degree rise is simply way outside human experience. The last time it was that hot, in the Pliocene, 3 million years ago, beech trees grew in the Transantarctic mountains and seas were 25 metres higher.

If we can limit warming to less than two degrees, knowing about 1.4 degrees is already locked in, the consequences will still be severe, but the risk of triggering runaway climate-change events (where we lose the capacity to control the consequences) lessens significantly.

This is why German Chancellor Angela Merkel and the British Conservative party — both from the right of European politics — have recently reaffirmed the importance of a two-degree limit. The Howard Government, by contrast, isn't even in the realm of reason on this question, with the Prime Minister saying a rise of four to six degrees might make life "uncomfortable" for some, but that it was difficult to predict with any certainty.

His comment shows fundamental ignorance. The planet as we know it will not survive past a five or six-degree rise: it is predicted that, at four degrees, hundreds of billions of tonnes of carbon locked up in Arctic permafrost — particularly in Siberia — will enter the melt zone, releasing the greenhouse gases methane and carbon dioxide in immense quantities.

Labor might know where the ballpark is, but they haven't bought an entry ticket yet. The ALP's Peter Garrett set out his party's policy on this page recently (The Age, 5/6), relying on a CSIRO submission to the Prime Minister's emissions taskforce that says a 60 to 90 per cent cut to industrialised countries' emissions is needed to stabilise climate change.

But Australia, as one of the worst emitters among the industrialised countries, requires a cut at the higher end of this range.

The CSIRO research and other research makes it clear that the "temperature stabilisation" associated with a 60 per cent cut is considered by many as too risky, giving us a massive 80 to 85 per cent chance of overshooting a two-degree target. Labor's policy for Australia of a 60 per cent cut by 2050 is therefore more about hope than science.

There is literally a world of difference between a two and three-degree rise in the impacts of climate change on both humans and the environment.

Caught between the science and the politics, Labor's Peter Garrett talks vaguely in the two to three-degree range, never being specific, never committing Labor to putting even one foot on the first rung of the climate change policy ladder — an unambiguous target.

And Labor does not have a short-term target — in many ways much more important than targets five decades away.

The Greens policy is to achieve emissions cuts of 30 per cent by 2020 and 80 per cent by 2050. This would give us an 80 per cent chance of keeping the temperature rise below two degrees. To maximise the chance of staying below two degrees, we must make big cuts early. For John Howard, a climate-change sceptic, this is more about smoothing over a political problem than real action. But Labor, too, falls short of the mark — they do not even set a temperature target.

Professor Tim Flannery, the Australian of the Year environmentalist, said recently his greatest wish was that political parties would state their "temperature limits" as to how hot the planet should get. The Greens recently moved a motion in the Senate to have a two-degree limit endorsed as Australia's target. The ALP joined with the Coalition to defeat the motion.

The challenge to the major parties is: just how hot are you prepared to let the planet get?

Dr Richard Di Natale and Adam Bandt are Greens candidates in this year's federal election.

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