Unexplored depths
Claudia Isabel Rittel
The importance of oceans in shaping the Earth's climate has
received recognition at a recently concluded international conference in
Indonesia.
A glimpse at life under the sea |
The oceans, so far, have hardly figured in the global-warming debate,
despite the fact that they are a heat and carbon sink. Accordingly, they
play a role in shaping the Earth's climate. The ocean depths are still
largely unexplored.
In May, an international conference in Indonesia has officially
recognised the significance of the sea for the first time, and tried to
assess the impact of climate change on the oceans.
Climate change will have massive impacts on the ocean, as marine
researchers agree. But even scientists have no clear idea what form such
changes will take. "The ocean ecosystem is too complex to be simulated
in a model," says Michael Türkay, head of the marine zoology department
of the Senckenberg Research Institute. "Many impacts in biology can only
be assessed in retrospect."
Some changes, however, can already be observed today. Because the
temperature of the North Sea has risen, many commercial fish species are
moving north. But there is a limit to how far north they can go.
Their migratory options are confined to where they find food. "Fish
populations are being crowded together," Türkay says. Because there is
no longer enough space for all, fish stocks are dwindling.
"On the whole," the marine biologist says, "we anticipate a
globalisation of fauna. Migration will lead to interbreeding, which will
reduce the diversity of species and make the system more susceptible to
disruption." In general terms, biodiversity allows an ecological system
to better adapt to change.
Türkay admits that he does not know what will happen precisely. "We
are groping in the dark." It is plainly unknown how individual species
will react to the changes ahead. Carbon dioxide (CO2) is a crucial
factor in climate-ocean interaction. So far, the oceans have absorbed
around a third of the CO2 released by human activity, though their
absorption capacity seems to be dwindling (note interview on page 260).
Today, single-celled marine algae produce as much oxygen as all of
the world's rainforests together. Algae require more than just water and
CO2 to produce oxygen; they also need nutrients such as nitrate or
phosphate.
Given an adequate supply of such nutrients, algae become assiduous
CO2 consumers, so attempts are being made to store CO2 in the oceans and
inject nutrients to stimulate algal growth. It is a clever idea but it
has yet to work in practice.
Natural nutrients exist in the oceans' depths. Currents carry them
from the deep sea to the surface. However, such currents will be
affected by climate change.
No one can forecast what will happen if major ecosystem parameters
change, for instance if the average temperature rises or a link in the
food chain disappears. Marine biological models can only depict
theoretical ecosystem interactions, because so little is known about the
oceans.
Although they cover twice as much of the earth as all the continents
put together, they are still largely unexplored, especially where the
sea bed drops below 1,000 metres.
"The only detailed knowledge we have of this huge area is confined to
around five square kilometres," Türkay points out. Which is why, he
adds, the German research ministry has now stepped up marine research.
To lend more weight to these issues, government representatives from
80 countries met in May for the first World Ocean Conference. Although
its final communiqué contained no concrete resolutions, the six members
of a new Coral Triangle Initiative - Indonesia, the Philippines,
Malaysia, Timor Leste, the Solomon Islands and Papua New Guinea - at
least agreed to protect their coral reefs better and curb overfishing.
- Third World Network Features
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