On course to suffer global warming of four degrees

We have already warmed the planet by 1 degree, relative to pre-industrial times, and are almost certainly experiencing an associated increase in costly, extreme weather events to say the least. In Australia, while it is impossible to be definitive about the cause of any single weather event, a list of prime suspects includes last decade's crippling drought, Victoria's Black Saturday bushfires of 2009 and this year's devastating floods.

Not scary enough for some, but as our chief climate change adviser, Ross Garnaut, warned earlier this year, "if we are seeing an intensification of weather events now, you ain't seen nothing yet".

Australia would need to lift its 2020 emissions reduction target to at least 25 per cent to play our fair share in giving the world a better-than-even chance of limiting warming to 2 degrees (the threshold level for potentially dangerous climate change), as governments agreed at the 2009 Copenhagen climate change summit and confirmed at Cancun.

Cross-party agreement on cuts of that order is hard to imagine in this country right now and the debate seems headed the other way in the US, which is alone responsible for 30 per cent of accumulated emissions between 1850 and 2002. [That figure is from a 2005 World Resources Institute study. Rounding out the top five were Europe (27 per cent), Russia and China (8 per cent each) and India (2 per cent). Australia ranked 15th, at 1 per cent of historical emissions]. On Tuesday, the EU voted against increasing its 2020 emissions reduction target from 20 to 30 per cent, absent from an international agreement.

At the end of May, the International Energy Agency warned that energy-related CO2 emissions had bounced right back from the financial crisis to reach a record high in 2010 and the prospect of limiting warming to 2 degrees was "getting bleaker".

Because most power stations that will be operating in 2020 are either built or under construction, the IEA said 80 per cent of projected 2020 emissions from the power sector were already locked in.

IEA chief economist Fatih Birol told the Guardian the two-degree goal was likely to be a "nice Utopia".

He continued: "I am very worried. This is the worst news on emissions. I was expecting a rebound, but not such a strong one. Room for manoeuvre is shrinking. This should be a wake-up call."

With low expectations for the climate change conference in Durban, South Africa later this year, there is now every chance the world will reach no binding agreement at all to reduce greenhouse gas emissions beyond the first commitment period under the Kyoto Protocol, which expires in 2012.

We can't all wait for each other to act. Australia at last is diving in, but there's a long hard swim ahead of us. If a carbon tax of $23 a tonne, rising sharply to drive emissions reductions of 5 per cent, sounds like a lot of effort and expense, it's a fraction of what we need to do to stop dangerous warming.

Without herculean effort we're on our way to a 4 degree warmer world. Indeed, one WikiLeaks diplomatic cable, published by the Herald last December, showed that's what our top intelligence agency, the Office of National Assessments, expects: 2 degrees warming by 2050 and 4 degrees by 2100.

A confidential briefing given by the ONA deputy director, Heather Smith, to the US embassy said south east Asia would be the region worst affected by climate change with decreased water flows from the Himalayan glaciers triggering a "cascade of economic, social and political consequences".

According to the leaked cable, Smith told the embassy the effects would be destabilising south east Asia by 2030: "South east Asia faces wild monsoons variations, with effects on littoral infrastructure, agriculture, marine currents and fish stocks. Coastal cities to be hit by subsidence and rising sea levels."

A conference in Melbourne this week, featuring a who's who of climate scientists, will explore what warming of 4 degrees or more means, including for Australia.

Keynote speaker Professor Hans Joachim Schellnhuber, director of the Potsdam Institute and climate advisor to the German Chancellor and to the EU, has previously said, in a 4 degree warmer world, the population " ... carrying capacity estimates [are] below one billion people."

Similarly, Professor Kevin Anderson, the director of the Tyndall Centre for Climate Change in the UK, was quoted in The Scotsman newspaper, ahead of the 2009 Copenhagen climate summit, saying the consequences of a 4 degree world were "terrifying".

"For humanity, it's a matter of life or death ... we will not make all human beings extinct, as a few people with the right sort of resources may put themselves in the right parts of the world and survive. But I think it's extremely unlikely that we wouldn't have mass death at 4[degrees]C. If you have got a population of nine billion by 2050, and you hit 4, 5 or 6[degrees]C, you might have half a billion people surviving."

Australian climate scientist David Karoly, alongside Melbourne University and CSIRO colleagues, will give a paper next week on likely changes to our climate in a 4 degrees scenario. They are exceedingly grim but Professor Karoly - who has warned "we are unleashing hell on Australia" - says he can't answer questions about Australia's likely carrying capacity, which depends on variables, like future willingness to pay, lifestyle and innovation. The hotter it gets, he says, "it just gets harder and harder to support more people".

In a recent blog posting David Spratt, co-author of Climate Code Red, drew the threads together on the implications of 4 degrees warming, and put them in plain language. The world would be warmer than during any part of the period in which modern humans evolved, he wrote, and the rate of climate change would be faster than any previously experienced by humans. Three degrees may be the "tipping point", where global warming could be driven by positive feedbacks, leaving us powerless to intervene as planetary temperatures soared and (quoting NASA climate scientist James Hansen) there will be "no return within the lifetime of any generation that can be imagined, and the trip will exterminate a large fraction of species on the planet". Half the world would be uninhabitable, food and water supplies insecure. Ocean ecosystems and food chains would collapse. "And we are talking about how we might adapt to a 4-degree warmer world," Spratt writes. "Have we gone mad?"

paddy.manning@fairfaxmedia.com.au

TWITTER: @gpaddymanning