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Can We Avoid 'Dangerous' Climate Change?

Steep emissions reductions unlikely

Ronald Bailey
December 16, 2004

"We must act sooner rather than later," declared Malte Meinshausen, a freelance climate consultant to various environmental activist groups. Meinshausen's presentation, jointly made with Bill Hare, the former climate policy director for Greenpeace International, focused on "Climate Risks and 2 Degrees Celsius." In climate circles, an increase in the Earth's average temperature of 2 degrees Celsius is widely regarded as the threshold for "dangerous" climate change. Using a simplified climate model Meinshausen looked at the risk of overshooting the 2 degree Celsius threshold for concentrations of greenhouse gases (GHG) at 400 parts per million (ppm), 450 ppm and 550 ppm by the year 2060. The current level of carbon dioxide in the atmosphere is 380 ppm.

Meinshausen calculated, based on various United Nations Intergovernmental Panel on Climate Change data, that at 550 ppm that there is an 84% chance of overshooting the 2 degree Celsius threshold. At its worst, an average temperature increase of 4.5 degrees Celsius cannot be excluded. At 450 ppm the risk of overshooting drops to 52% and at 400 the chance of overshoot is only 26%. Based on recent climate modeling results of the Hadley Centre in the United Kingdom, Meinshausen concluded that at there is a 100% chance that average temperatures would rise over 2 degrees Celsius at GHG concentrations of 550 ppm.

After calculating these risks, Meinshausen then asked, "What are the necessary global emissions reductions to achieve each level of concentration by 2060?" Meinshausen projected various trajectories for global reductions of annual GHG emissions aimed at achieving each level of stabilization. He assumed that GHG emissions peak in 2015 and that the whole world -- all of the developed and the developing countries -- begins reducing GHG emissions at that point. To reach GHG stabilization by 2060 at the 550 ppm level, the GHG emissions by the entire world would have to be reduced to those emitted in 1990. This implies at least a 13% emissions reduction since annual global carbon dioxide emissions are more than 13% higher than 1990 emissions. For 450 ppm, GHG emissions would have to be cut by 30-40% below the level emitted in 1990 and to achieve stabilization at 400 ppm GHG emissions would have to be slashed to 40-50% of 1990 levels.

Another panel discussion by the International Energy Agency (IEA) later in the day about world energy and emissions trends to 2030 shows that Meinshausen and his fellow activists are living in a total fantasy world.

Claude Mandil, executive director of the IEA, outlined two scenarios for the growth in world energy demand from 2002 to 2030 in its World Energy Outlook 2004 report. The first is a reference case which assumes completely static energy policies until 2030. In the reference case, annual global primary energy demand grows by 60% between 2002-2030 and emissions of carbon dioxide increase by 62% per year. In an Alternative Scenario case, the IEA assumed that all even remotely considered energy and emissions policies are adopted. In that scenario global primary energy demand rises by 50% and carbon dioxide emissions would rise by about 52% annually.

The vast majority of the increase in energy demand and emissions results from economic growth in the developing world over the next 25 years. The WEO 2004 report noted in its reference scenario that 1.6 billion people lacked access to electricity in 2002. Even more distressing is the fact that the IEA reference scenario projects that 1.4 billion people will still lack electricity by 2030. To get electricity to more than half a billion people who, under IEA's reference scenario lack electricity in 2015, will require about $200 billion of additional investment in electricity supply. Even that would still leave about a billion people without electricity. One wonders how many billions do Meinshausen and other activists want to leave without access to modern fuels?

Finally, in the real world, absent transformative technological breakthroughs in energy production, whatever the chances that average temperatures may one day exceed 2 degrees Celsius, there is absolutely no chance that steep emissions reductions scenarios are even remotely possible.

Ronald Bailey is Reason magazine's science correspondent.


Ronald Bailey is Science Correspondent


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