摘要：This letter evaluates Japan's so-called 'Mamizu' climate policies proposed in mid-2009 in
terms of the implied rates of decarbonization of the Japanese economy for short-term and
long-term targets. The letter uses the Kaya identity to structure the evaluation, employing
both a bottom up approach (based on projections of future Japanese population, economic
growth, and technology) and a top down approach (deriving implied rates of
decarbonization consistent with the targets and various rates of economic growth). Both
approaches indicate that the Japanese economy would have to achieve rates of
decarbonization of 2.6% to meet a 2020 target of reducing emissions by 15% below 2005
levels, and 5.0% to meet a 2050 target of an 80% reduction below 2005 levels. A
target of 25% below 1990 emissions proposed by the opposition party (which
subsequently formed a government following elections in August 2009) implies a rate of
decarbonization of 4.6% annually to 2020. The letter argues that international criticism of
Japanese Mamizu climate policy proposals as being too weak was unfounded, and if
anything, the proposals may have been too ambitious. In either case, climate
policy would be strengthened through the support of a diversity of approaches to
decarbonization.
