But Roger Pielke Jr of the University of Colorado, US, has calculated the rates of decarbonization that Japan would need to achieve to reach this goal and he believes that far from being too weak, the target is in fact too ambitious. In September Japan's new Prime Minister Yukio Hatoyama announced an even more stringent target of 25% cuts over 1990 levels by 2020 at the UN Climate Change Summit in New York. The previous target was roughly equivalent to an 8% cut over 1990 levels.
"The goals of climate policies are currently mismatched with the ability of policy to meet those goals," Pielke told environmentalresearchweb. Pielke believes that this is a problem not just for Japan but for many countries, including the US, India, China and the EU.
"Countries appear to have agreed on a practical level to let this shared dissonance persist, but the reality is that it only delays the time when climate policy will collapse and need to be rethought," he added. "Policies ultimately are judged on what is done, not simply on what is promised. My analysis implies that the difference between promises and performance is unsustainable."
Pielke found that to meet the 2020 target of a 15% reduction in carbon emissions below 2005 levels would require a decarbonization rate of 2.6% in the Japanese economy. This would mean achieving a carbon intensity (amount of carbon per unit of energy) by 2020 lower than that of France's in 2006, equivalent to a decrease in emissions per unit GDP (gross domestic product) of about 33%. Pielke reckons that this would be a monumental achievement.
What's more, achieving emissions reductions of 80% below 2005 levels by 2050 would require decarbonization of 5.0%. And to meet the latest target – 25% below 1990 emissions – requires a 4.6% rate of decarbonization annually to 2020.
Japan proposed to meet the Mamizu target by constructing nine new nuclear power plants, installing 5 million kW of wind power, installing solar panels on 5.3 million homes, boosting the proportion of newly built homes with high insulation standards from 40% to 80%, and increasing the share of new vehicles that are "next-generation" from 4% to 50%. Pielke believes that these are ambitious goals.
"The promise of a 25% reduction in Japan's emissions by 2020 is highly unlikely to occur, and saying this with stronger language would not be inappropriate," said Pielke. "The target can only be met by some sort of creative accounting such as by using international offsets, and even then it would be very difficult."
The Mamizu policy was named because it aims for "genuine clear water" – making a real difference to Japan's emissions rather than including carbon offsets or land-use changes in the accounting.
"For me, the idea to rigorously evaluate emissions-reductions commitments in terms of their implied rates of decarbonization crystallized in my mind when working on a Commentary for Nature in 2007 with Tom Wigley and Chris Green on assumptions of 'spontaneous decarbonization' in the scenarios of the IPCC," said Pielke. "Remarkably (at least to me) promises made about emissions reductions are only infrequently rigorously evaluated with respect to their realism or practicality."
Earlier this year Pielke carried out a similar analysis for UK climate policy. "Next up is Australia," he said. "And for a book I have forthcoming in 2010 I will conduct a similar analysis for many of the top emitters worldwide. The picture that emerges is sobering indeed."
Pielke reported his work in Environmental Research Letters.