As revealed by Bernard Keane this morning, this Friday Ross Garnaut looks set to propose a carbon reduction trajectory based on a 0-15% reduction on 2000 emission levels by 2020.

So now that we’ve got the numbers, what will the landscape look like in 2100, based on that kind of target?

Earlier this week, the Climate Institute put together modelling based on two different targets for a glimpse into the future landscape of Australia in an even hotter, more inhospitable climate.

Back when Garnaut released his interim report in February, he acknowledged that even stabilising atmospheric carbon dioxide at 550 parts per million (a level that climate scientists agree gives virtually no chance of staving off a two degree rise in temperature) is virtually impossible,  unless the world achieves an “urgent, large and effective global policy change”.

Garnaut was criticised by lobby groups at the time for not modelling at the lower target of a carbon concentration of 400 parts per million (a target that some claim is nigh impossible). Instead, Garnaut modelled his report on both 550 ppm and 450ppm — 450 requires global emissions to peak around 2010 and then fall to less than half that by mid-century.

As Keane reports this morning, according to Greenpeace, a 15% reduction would lead to stabilisation at a carbon dioxide concentration of 450 ppm.

No reduction (550 ppm, and a 2.3-2.8 degree rise) would mean much worse.

According to the IPCC, a concentration of Co2 emissions at 400 ppm increases the chance of exceeding a temperature rise of over 2 degrees by 27%. At 450 ppm the chances of exceeding 2 degrees shoot up to 54% and at 550ppm, 82%.

The Climate Institute’s table chronicles the impacts of the different targets on the Australian environment by 2100.

The column denoting ‘hot, dry extreme case (the “bad end story”) denotes the scenario should the environment react even more sensitively than current modelling suggests.

 

Australia in 2100 at 550ppm according to The Climate Institute’s modelling, will see a 20% decline in the value of irrigated agricultural production in the Murray Darling Basin; 100 — 300% increase in extreme fire weather and the “disappearance of the Barrier Reef as we know it.”

At 450 ppm, the upper end of Garnaut’s modest target proposal of 15%, Australia faces a 6% decline in the value of irrigated agricultural production in the Murray Darling Basin; and mass bleaching of the Barrier Reef twice as common as today; 720,00 people at risk of dengue fever and significant species extinction in north Queensland and Western Australia.

Peter Fray

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