Report maps out investment strategy for fighting climate change

The world needs a significant investment now to kick-start climate change mitigation, according to a new study from European researchers. However, subsequent investments will have a more pronounced effect. And if we invest 2 per cent of global GDP in averting climate change, we have a 90 per cent chance of keeping global temperatures at 2 per cent above 19th century levels.

In a paper published in the Proceedings of the National Academy of Sciences called Near-linear cost increase to reduce climate-change risk, European researchers found a carbon dioxide “sweet spot”, where limiting the density of carbon in the atmosphere by a relatively small amount gave us a significantly higher probability of meeting climate change targets.

The paper suggested that cutting carbon levels by relatively small amounts could sharply increase the probability of keeping global temperature rises under 2°C. We have a 40 per cent chance of hitting that target if we limit the amount of carbon dioxide in the atmosphere to 450 ppmv (parts per million by volume). Keeping that density at 400 ppmv gives us an 80 per cent chance. "That's an increase in probability of 40 per cent for a relatively small concentration reduction of 50 ppmv," it said.

The more ambitious the temperature contraints, the higher the necessary financial investment needs to be to get a significant chance of succeeding, the report said. We must invest relatively high amounts to stand any chance at all of keeping temperatures at 2°C. However, as we invest more, the relationship between investment and probability of success evens out. Investing just over 0.5 per cent of GDP gives us a mere 10 per cent chance of constraining global temperature increases to 2°C above 19th century levels. Increasing that to 1.1 per cent of GDP gives us a 40 per cent probability. A 2 per cent investment gives us a 90 per cent chance of success.

Researchers from the Environmental Systems Analysis Group at Waginengen University in the Netherlands worked on the report with others from the Netherlands Environmental Assessment Agency and the Potsdam Institute for Climate Research in Germany.

"All of this leads to a compelling argument for seeking more certainty in limiting climate-change damages by lowering GHG concentrations, especially because monetary or nonmonetary damages appear to rise rapidly with temperature, " concluded the report.

Much depends on how the money is invested. The Sierra Club is calling for a cap strategy to help mitigate global warming risk. "A large part of the revenue from any cap system needs to be invested in developing the technology and industries that will create the most jobs and reduce our emissions," it said in a statement. "The more we invest now, the stronger our US economy will be."