9
absorbed exceeds the reduction of CO 2 emissions associated with efforts to regulate emissions at present.
2. Maintaining and improving the CO 2 sequestration and storage functions in terrestrial and marine ecosystems is extremely important for mitigating climate
change effects. The contribution of forests to these functions is evaluated through
mechanisms such as the market economy. Because the contribution of the ocean
remains underestimated, the purpose of this report is to highlight the contribution of the oceans to the reduction of atmospheric CO 2 concentrations and the
important role the oceans, and especially shallow coastal areas, play in stopping
further degradation. An option for achieving that goal might be introduction of a
market economy mechanism to evaluate the contribution of CO 2 sequestration
by the ocean. Exploring the effectiveness of a CO 2 reduction plan with the ocean
is also aimed as the main focus.
3. The ocean plays a major role in the global carbon cycle of Earth. The ocean is
the largest sink for long-term sequestration of carbon. In fact, a little over 90%
of the CO 2 on the planet (40 teratons: tera means 10 raised to the power 12, i.e.,
10
12
) is found in the ocean.
4. Coastal ecosystems with plant foundation species such as mangrove forests, saltmarshes, and seagrass beds account for less than 0.5% of the ocean area, but
these act as the largest sink of blue carbon. They account for 50–71% of the total
carbon stock preserved in marine sediments. Although the plant biomass in these
three ecosystems is only 0.05% that of terrestrial plants, annual carbon storage
in these ecosystems is roughly equivalent to the amount of carbon stored by all
terrestrial plants on Earth. In other words, these three ecosystems are the most
effective global carbon sink. Hereinafter, the mangrove forest, saltmarsh, and
seagrass ecosystems are collectively referred to as the blue carbon ecosystem).
5. The blue carbon ecosystem is the most efficient ecosystem for storing carbon,
but it is also the most rapidly disappearing ecosystem on Earth. Its rate of disappearance is more than 4 times that of tropical rainforests. Recently, the average
rate of decrease of the blue carbon ecosystem has been preliminarily estimated
to be 2–7% per year. This rate of decrease is seven times the rate half a century
ago. If measures for protecting it are not implemented, most coastal vegetation
may be lost within the next 20 years. If further degradation of coastal vegetation
is prevented and logging of tropical rainforests is greatly reduced, there is a possibility that recent CO 2 emissions can be reduced by as much as 25%.
6. Maintaining the blue carbon ecosystem will also have positive economic effects;
it will improve food safety and living standards and increase the ability of people
living in coastal areas to adapt to the effects of climate change. Although the
coastal area is only 7% of the total ocean area, the blue carbon and coral reef
ecosystems are among the most important fishing grounds all over the world;
they provide about 50% of the worldwide fisheries resources. Approximately
3 billion people are provided with nutrition essential for life activities from
coastal areas. Also, coastal areas provide about 50% of animal protein and minerals consumed by 4 billion people living in developing countries.
1 Blue Carbon: Characteristics of the Ocean’s Sequestration and Storage Ability…
absorbed exceeds the reduction of CO 2 emissions associated with efforts to regulate emissions at present.
2. Maintaining and improving the CO 2 sequestration and storage functions in terrestrial and marine ecosystems is extremely important for mitigating climate
change effects. The contribution of forests to these functions is evaluated through
mechanisms such as the market economy. Because the contribution of the ocean
remains underestimated, the purpose of this report is to highlight the contribution of the oceans to the reduction of atmospheric CO 2 concentrations and the
important role the oceans, and especially shallow coastal areas, play in stopping
further degradation. An option for achieving that goal might be introduction of a
market economy mechanism to evaluate the contribution of CO 2 sequestration
by the ocean. Exploring the effectiveness of a CO 2 reduction plan with the ocean
is also aimed as the main focus.
3. The ocean plays a major role in the global carbon cycle of Earth. The ocean is
the largest sink for long-term sequestration of carbon. In fact, a little over 90%
of the CO 2 on the planet (40 teratons: tera means 10 raised to the power 12, i.e.,
10
12
) is found in the ocean.
4. Coastal ecosystems with plant foundation species such as mangrove forests, saltmarshes, and seagrass beds account for less than 0.5% of the ocean area, but
these act as the largest sink of blue carbon. They account for 50–71% of the total
carbon stock preserved in marine sediments. Although the plant biomass in these
three ecosystems is only 0.05% that of terrestrial plants, annual carbon storage
in these ecosystems is roughly equivalent to the amount of carbon stored by all
terrestrial plants on Earth. In other words, these three ecosystems are the most
effective global carbon sink. Hereinafter, the mangrove forest, saltmarsh, and
seagrass ecosystems are collectively referred to as the blue carbon ecosystem).
5. The blue carbon ecosystem is the most efficient ecosystem for storing carbon,
but it is also the most rapidly disappearing ecosystem on Earth. Its rate of disappearance is more than 4 times that of tropical rainforests. Recently, the average
rate of decrease of the blue carbon ecosystem has been preliminarily estimated
to be 2–7% per year. This rate of decrease is seven times the rate half a century
ago. If measures for protecting it are not implemented, most coastal vegetation
may be lost within the next 20 years. If further degradation of coastal vegetation
is prevented and logging of tropical rainforests is greatly reduced, there is a possibility that recent CO 2 emissions can be reduced by as much as 25%.
6. Maintaining the blue carbon ecosystem will also have positive economic effects;
it will improve food safety and living standards and increase the ability of people
living in coastal areas to adapt to the effects of climate change. Although the
coastal area is only 7% of the total ocean area, the blue carbon and coral reef
ecosystems are among the most important fishing grounds all over the world;
they provide about 50% of the worldwide fisheries resources. Approximately
3 billion people are provided with nutrition essential for life activities from
coastal areas. Also, coastal areas provide about 50% of animal protein and minerals consumed by 4 billion people living in developing countries.
1 Blue Carbon: Characteristics of the Ocean’s Sequestration and Storage Ability…