Guest Weblog By Kiminori Itoh “Soot And The Arctic Ice – A Win-Win Policy Based On Chinese Coal Fired Power Plants”

Kiminori Itoh of Yokohama National University has prepared a guest weblog for us. It is titled “Soot And The Arctic Ice – A Win-Win Policy Based On Chinese Coal Fired Power Plants” [UPDATE: see also Mike Smith's Guest Weblog on this subject]


As you saw in a recent weblog in Climate Science, China appears to be modifying the global climate through aerosol emission from a large number of coal fired power plants: August 12, 2009, New Paper “Increase In Background Stratospheric Aerosol Observed With Lidar” By Hofmann Et Al 2009.  This paper gave me an idea that soot from China may be responsible for the recent reduction of the Arctic ice, which finally leads me to a Win-Win policy on coal fired power plants in China, as you see below.

The target of the paper of Hofmann et al was  sulfate aerosol transported into stratosphere. Thus, its main effect on the global climate is cooling of the troposphere and warming of  the stratosphere similar to volcanic eruptions. In fact, this paper was introduced in Science (24 July 2009, p. 373) with the title of “China’s Human Volcano.”

The Chinese aerosol, however, can have another effect on the climate. That is, a possible influence of soot on the Arctic ice. It seems to me that Hofmann et al.’s paper, together with other recent findings, gives evidence for this possibility as follows:

1) Hofmann et al’s paper shows that stratospheric haze became densest in 2007 and declined a little after that. According to their claim, this is associated with the changes in sulfate emissions from China. This fact reminds me that the ice extent in the Arctic sea was significantly reduced in the 2007 summer and recovered after that. Since the amount soot should be proportional to that of sulfate, also the amount soot transported to the Arctic may have a peak in 2007, and may explain the dramatic reduction of the sea ice extent; the soot deposited onto the ice surfaces absorbs sun light of Arctic summer, gives heat to the ice, and lets it melt. This process should be particularly effective during summer of the Arctic when the sun does not set.

2) About half of the recent temperature increase in the Arctic region is reportedly due to aerosols (combination effects of sulfate and soot) (D. Shindell and G. Faluvegi, Nature Geosci. 2, 294-300 (2009)); this result convinces one that the influence of soot on the Arctic environment does exist.

3) There are other recent papers on soot: e. g., “Atmospheric brown clouds: Hemispherical and regional variations in long-range transport, absorption, and radiative forcing,” V. Ramanathan et al., J. Geophys. Res. vol. 112, D22S21, doi:10.1029/2006JD008124, 2007.

From these results, I suspect that the soot from China is responsible for the recent reduction of sea ice in the Arctic summer. To verify this, detailed chemical analyses, such as carbon allotropes, should be made if the soot can be sampled from the ice (this may be an interesting project).

Thus, I can claim that the influence of the soot is likely large. Then, according to the spirit of the precautionary principle, the soot from China should be reduced even if  the scientific basis is not sufficient. The precautionary principle should be applied not just to CO2, but to other primary factors of climate changes. If this is not possible just because there is no statement on soot in the FCCC (Framework of Convention of Climate Change), we need another convention (or protocol) which enables us to treat soot properly. Otherwise, countermeasures on climate change will be useless.

Now, I want to point out that the reduction of the Chinese soot can become a Win-Win policy for China as well as for other countries. About 80% of the Chinese electricity comes from coal fired power plants. The CO2 emission from China in 2004 was about 2.27 billion metric tons, which was 8.6% of the world emissions (26.3 billion metric tons). But, their efficiency of energy production is still low (34.6% as an average), and emissions other than CO2 and aerosol (i. e., mainly SOx, NOx and mercury) bring heavy health problems as well. In fact, resultant atmospheric pollution causes 300 thousands to 400 thousands of deaths a year.

If countries like Japan, which has advanced technologies of coal fired power plants (e. g., energy production efficiency being 41.1% in Japan), can cooperate with China to increase the efficiency of energy production and to decrease all kinds of emissions, this will become a true Win-Win policy. China can save a lot of human lives and working hours, can reduce the influence of the aerosol on the global climate, and in addition, can reduce CO2 emission. The other countries also benefit from this policy, including economical ones and a reduction of transboundary pollution.

This Win-Win policy actually will reduce the emission of CO2. Just from this aspect, it is much better than the cap-and-trade policy which in fact will increase the CO2 emissions. Moreover, and importantly, when considering a large capacity of coal reserves, this is a reasonable tactics in near future.

With this kind of Win-Win policies, developing countries like China can agree with developed countries on their energy policies. There will be no progress in the negotiation between them if the developing countries can participate in the climate policies only through the reduction of CO2. We need flexible approaches for complicated issues like the climate changes.

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