Atmospheric CO2 to reach first danger level by 2028: new research

Stan Beer
Tuesday, 22 May 2007 12:10

Science - Climate

Carbon dioxide concentration in the atmosphere is likely to reach the first climate change danger level by 2028 and if emissions growth continues at the present rate, the point of no return will be reached with dire consequences by by 2046, according to new scientific research published at the National Academy of Sciences.

A paper published this week in the Proceedings of the National Academy of Sciences details a finding that carbon emissions, the principal driver of climate change, are growing a far greater rate than expected over recent years. According to the paper, the average growth rate of carbon dioxide emissions increased from 1.1% a year in the 1990s to a 3% increase per year in the 2000s.

Lead author of the paper, Dr Mike Raupach from CSIRO Marine and Atmospheric Research and the Global Carbon Project, says that nearly eight billion tonnes of carbon were emitted globally into the atmosphere as carbon dioxide in 2005, compared with just six billion tonnes in 1995. He says, that while deforestation has also been an important factor, contributing about 1.5 billion tonnes of carbon emissions into the atmosphere, burning fossil fuels is the main culprit.

What's more, if emissions continue at the present rate, the world will hit its first danger point of carbon dioxide atmospheric concentration of 450 parts per million by 2028 to 2030. At present, the world is at 380ppm, while the pre-industrial age levels were at 280ppm.

"The consensus is that if we manage to bring CO2 to equilibrium at 450ppm, we would be looking at a temperature rise of 1 to 1.5 degrees above pre-industrial levels, some changes to rainfall patterns, some melting of the Arctic, significant acidification of the oceans through CO2 rise and so forth. But these are issues which would not cause widespread devastation," Dr Raupach told iTWire.

"If we reach 550ppm, we're getting into 2 to 2.5 degree temperature rise and the amount of climate damage that we would be looking at will in some cases would probably involve crossing thresholds that we can't recover from. If we keep on the present growth projectory then we get there by about 2046.

According to Dr Raupach, reasons behind the increasing inefficiency lay with both developing and developed countries.

"A major driver of the accelerating growth rate in emissions is that, globally, we're burning more carbon per dollar of wealth created," Dr Raupach says. "In the last few years, the global usage of fossil fuels has actually become less efficient. This adds to pressures from increasing population and wealth."

"As countries undergo industrial development, they move through a period of intensive, and often inefficient, use of fossil fuel. Efficiencies improve along this development trajectory, but eventually tend to level off. Industrialised countries such as Australia and the US are at the levelling-off stage, while developing countries such as China are at the intensive-development stage. Both factors are decreasing the global efficiency of fossil fuel use," says Dr Raupach.

According to Dr Raupach's figures, China with nearly five times the population of the US is now emitting almost as much carbon per year as the US but is a much lower emitter per person.

He says that China's emissions per person are still below the global average. "On average, each person in Australia and the US now emits more than five tonnes of carbon per year, while in China the figure is only one tonne per year. Since the start of the industrial revolution, the US and Europe account for more than 50% of the total, accumulated global emissions over two centuries, while China accounts for less than eight per cent. The 50 least developed countries have together contributed less than 0.5 per cent of global cumulative emissions over 200 years."

Dr Raupach says that Australia, with 0.32 per cent of the global population, contributes 1.43 per cent of the world's carbon emissions.

He says recent efforts globally to reduce emissions have had little impact on emissions growth. "Recent emissions seem to be near the high end of the fossil fuel use scenarios used by the Intergovernmental Panel on Climate Change (IPCC). Our results add to previous findings that carbon dioxide concentrations, global temperatures and sea level rise are all near the high end of IPCC projections."

Dr Raupach led an international team of carbon-cycle experts, emissions experts and economists, brought together by the Global Carbon Project, to quantify global carbon emissions and their drivers.

"In addition to reinforcing the urgency of the need to reduce emissions, an important outcome of this work is to show that carbon emissions have history. We have to take both present and past emissions trajectories into account in negotiating global emissions reductions. To be effective, emissions reductions have to be both workable and equitable," he says.

Dr Raupach says there are four technical ways that the world can employ to slow the carbon emissions rate: conservation of energy; non-fossil fuel energy; more efficient of fossil fuels, including clean coal; and avoiding deforestation.