Is 350 the right carbon target?

October 19, 2009

The campaign has already made an important impact worldwide. The recent spike in official actions — now well above 2000 — suggests the number of people who support stabilising atmospheric CO2 at under 350 parts per million (ppm) has grown phenomenally in the past few months.

It has played a big role in debunking the pseudo science peddled by the governments and corporations who want to avoid taking serious action on climate change. Many developed countries, including Australia, officially say 450ppm is a safe target.

The campaign is also good because it has drawn attention to the fact that there is already too much CO2 in the atmosphere. There is no safe way to keep polluting.

To achieve 350ppm, net carbon emissions must be rapidly cut to zero, and big amounts of CO2 must be drawn down from the atmosphere.

But does the 350 target truly reflect the climate science, or is an even lower target needed?

In Australia, most climate action groups support a lower target: 300ppm.

This was the long-term objective settled upon by the 150 groups represented at Australia's Climate Action Summit in January. The summit concluded that 300ppm was "in line with what science and global justice demands".

In a January post on the Climate Code Red blog, David Spratt said NASA scientist James Hansen's research confirmed that 300, not 350, was the right target.

Hansen said a drop to 350ppm from today's 390ppm was needed to ensure the Antarctic ice sheet is kept. But he also said a fall in carbon levels to 300-325ppm is essential to restore the Arctic ice sheet, which has lost 70-80% of its volume in the past 50 years.

This is crucial because "if you don't have a target that aims to cool the planet sufficiently to get the sea-ice back, the climate system may spiral out of control, past many 'tipping points' to the final 'point of no return'", said Spratt.

Restoration of the Arctic sea ice is needed to halt the thawing of permafrost soils in Siberia and Canada, for example. If released in large quantities, the methane gas now trapped below the frozen soils could trigger runaway global warming. Australia CEO Blair Palese told Green Left Weekly that the 350 target should be seen as a critical first step to a safe climate. "It's a first step", she said. It's a starting point, to work on. It by no means means we should just stop at 350."

Palese pointed out that many groups in Australia who support 300ppm are enthusiastic supporters of's October 24 actions.

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