Aussie agriculture to be hit hard by climate change

Fairfax

DRY TIMES: A report says Australia's agriculture will be hard hit by climate change.

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Climate change, if left unchecked, stands to reduce Australia's agricultural productivity by up to 27 per cent over the next 75 years, and devastate agricultural output in some of the poorest regions of the world, a study estimates.

The study, by US economist William Cline of the Peterson Institute of Institutional Economics in Washington, estimates that global warming will cut agricultural productivity worldwide by between 3 per cent and 19 per cent by 2080.

Tropical and subtropical agriculture in particular will be devastated, Dr Cline estimates, with already poor areas such as Sudan and equatorial Africa seeing agricultural productivity decline by as much as 50 to 60 per cent.

Conversely, some colder areas stand to gain, particularly if the carbon fertilisation theory - the prediction that increased carbon dioxide in the atmosphere will make plants grow faster - proves to be valid, he says.

The study, Global Warming and Agriculture: Impact Estimates by Country, assumes that, unchecked, temperatures will rise by 4 to 5 degrees by 2080, and estimates what this would mean for agricultural output.

Dr Cline, a long-time advocate of a carbon tax, finds that the unresolved debate over carbon fertilisation is critical to the outcome.

Assume business as usual with no carbon fertilisation, he says, and agricultural productivity would slump by 20 per cent worldwide by 2080, cutting the value of output by $US186.5 billion in 2003 dollars.

In that scenario, almost all countries would suffer, with only Tibet, Scandinavia, New Zealand, Egypt and the northern US seeing productivity rise. Australia's farm productivity would decline by 27 per cent, mainly in Western Australia and Queensland, Dr Cline estimates.

If the carbon fertilisation theory is correct, however, and increases plant growth by 15 per cent, then the net losses to world farm productivity would shrink to 3 per cent, a cost of $US38 billion a year.

Global productivity overall would not decline so much as be radically reallocated - largely from the global have-nots to the haves.

Colder areas would be significantly better off, including Europe and Russia, most of China, Canada, north and central US, and New Zealand. But warmer regions, including all of Australia, would suffer big losses.

"The estimates for Australia indicate losses of around 16 per cent even with carbon fertilisation, with potentially much larger losses", Dr Cline sums up.

"For Australia, one of the two steadfast opponents of the principal international initiative to date against global warming (the Kyoto Protocol), the results suggest that a more positive position on global warming abatement would be in its long-term interests."

Outside Africa, India would be the biggest loser. The study estimates that even with carbon fertilisation, India's farm productivity would slump by almost 30 per cent, costing it $US38 billion a year.

India so far is far behind China in tackling wasteful emissions.

Mexico would be another big loser, its farm productivity falling 26 per cent, and Central America would also suffer badly. Indonesia and Brazil would be only moderately worse off.