January 2, 2009 08:07 AM
The researchers, from Germany and the Netherlands, published an article in The Journal Proceedings of the National Academy of Science
(PNAS) in which they say they’re confident that global governments stand a 90 percent chance of limiting temperature rises to 2 Celsius (3.6 Fahrenheit) above pre-industrial temperatures if they invest
2 percent of the global gross domestic product (GDP) in climate mitigation packages from 2005 until the year 2100.
Among climate change research, the general approach taken is to set a future level of CO2 emissions and then infer the implied emissions pathways. But the Dutch and German scientists based their calculations on a predetermined ceiling for future temperature rises.This makes more sense, says Michiel Schaeffer, the report’s lead author who’s attached to Wageningen University in the Netherlands. He explains that cost estimates associated with limiting a predetermined level of carbon emissions often rise rapidly, even exponentially, as the scale of emission reductions from a reference level increases. It’s much easier to look at the bright side and focus on temperature reductions and the success levels achieved.
Schaeffer also believes that looking at the problems from a temperature point of view is more relevant for real-life impacts other than CO2.
“[Co2] concentrations don’t tell you that much about what happens in terms of rainfall ” or to society,” Schaeffer told a Reuters journalist.
You might wonder whether this is really true or relevant. After all, aren’t we faced with a certain, undeniable level of CO2 in the air that simply needs scrubbing out? But at the decision-maker level, working with a global mean temperature as the normative target changes the game considerably. It’s all a matter of math, the scientists show. The qualitative relationship between the likelihood of achieving temperature decreases and the costs of climate change mitigation is positive. Mitigation costs rise proportionally to the likelihood of meeting a temperature target across a range of concentration levels.
Climate targets simply have “constant returns to scale”. The reason is that there is a counterbalancing rapid rise in the probabilities of meeting a temperature target as concentration is lowered, the scientists say.
And they have the numbers to support this. Massive initial investments are needed to book successes at slowing temperature rises. But after a certain level of achievement has been reached, the costs will have positive returns on warming. The researchers point out that early investment of only 0.5 percent of world GDP (approximately what the EU currently spends) will not nearly be enough because there’s only a 10 percent chance that temperatures actually decline by 2 degrees. Increasing the initial investments to one percent of GDP yields a 40 percent chance of success. Only if 2% of global GDP is spent on the environment do we arrive at a scenario which ensures a 90% chance of successfully reducing temperature rises by 2%.
Costs might be high initially, but if all works to plan, they won’t spiral out of control afterwards. Most governments expect the opposite. They fear that the higher the initial costs, the higher the future expenditure will be too.
“It gets easier once the world gets going ,” according to Schaeffer.
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