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Program Leader
Prof. Motoyoshi Ikeda
（Division of Oceanic and Atmospheric Science)
Graduate School of Environmental Earth Science and Institute of Low Temperature Science have started the 21st century Center of Excellence (COE) program in the fall of 2002.
Our program title "Prediction and avoidance of an abrupt change in the bio-geosphere system" means that a 100-year-scale abrupt change as consequence of an inability of environment's self-recovery, which could be caused by the interactions between the geosphere and the biosphere.
"Global warming by CO2", "ozone depletion", "forest destruction by exploitation" and "pollutants" are not influencing the environment independently. A possible feedback loop is that "Low absorption of CO2 caused by forest destruction" promotes "global warming", and then, "global warming" in turn enhances "forest destruction". They interact each other. Therefore, we need to understand these phenomena as a coupled system and to predict a future change. We are trying to understand and predict the phenomena by clarifying on the basis of bio-geoscience and intercomparison between the high latitude region and the low-to-mid latitude region. Our final objective is to avoid the abrupt change by not controlling nature but helping it from the cycle between natural ecosystem and material circulation.
Our roles in the education are guiding Asian younger generation to environmental-oriented personnel and proceeding an international collaboration for the prediction of the environmental change. We have hired 8 postdoctors who play a central role in our project. We have also assigned 20 students as research assistants in the school and are educating them through the project. We plan to hold a symposium in this autumn with the 10th anniversary celemony of our graduate school.
In the high latitude region, CO2 is absorbed into the ocean by enhanced marine productivity, but in the low latitude region, it is emitted to the atmosphere. The productivity in the North Pacific Ocean is seriously influenced by declining of the global ocean conveyor belt and also vertical mixing following the proceeding global warming. If it continues to a critical level, the marine ecosystem might change its nature, and the high latitude region would start emitting CO2. As a final stage, these phenomena might accelerate global warming. We investigate the key process of the ecosystem and the carbon-nitrogen circulation by observations. We also build a numerical model of ocean physical, bio-geochemical processes and verify it against the observations.
On the other hand, permafrost deterioration and biodiversity reduction which is caused by ozone depletion may retard forest growth in the geosphere. An increase in ultraviolet rays B by a decrease in ozone causes the decomposition of soil and emission of gas such as methane, which then promotes global warming. To predict the CO2 absorption to forest, we develop the bio-geo-atmosphere model which takes in the effect of global warming and ozone depletion. The model will be verified against various data sets collected in Siberia and the tropical areas.
As indicated above, interactions between biosphere and geosphere are the key to the global change. Fixation of carbon in the ocean is suggested as one of the effective methods to avoid the abrupt change. However, we will closely assess such a method, and publicize the assessments of any suggestion to avoid the abrupt change. For an overall purpose, we are proposing the protection and improvement of the global environment.
Graduate School of Environmental Science
Hokkaido University
N10 W5, Sapporo 060-0810, JAPAN
