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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