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Special
Report submitted to the Federal Government
Carbon
dioxide poses double risk to oceans and coasts
Latest research findings show that failure to check
mankind’s emissions of carbon dioxide will have severe consequences
for the world’s oceans. The marine environment is doubly affected:
continuing warming and ongoing acidification both pose threats. In combination
with over-fishing, these two threats are further jeopardizing already
weakened fish stocks. Sea-level rise is exposing coastal regions to mounting
flood and hurricane risks. To keep the adverse effects on human society
and ecosystems within manageable limits, it will be essential to adopt
new coastal protection approaches, designate marine protected areas and
agree on ways to deal with refugees from endangered coastal areas. All
such measures, however, can only succeed if global warming and ocean acidification
are combated vigorously. Ambitious climate protection is therefore a key
precondition to successful marine conservation and coastal protection.
Berlin,
31. May 2006. Today, the German Advisory Council on Global Change
(WBGU) submits to Parliamentary State Secretaries Michael Müller
(Environment) and Thomas Rachel (Research) its new special report “The
Future Oceans: Warming Up, Rising High, Turning Sour”. In its report,
WBGU shows that climate change is having severe impacts on the state of
the oceans. Human activities are unleashing processes of change in the
oceans that are without precedent in the past several million years. Three
processes are critical: ocean warming, ocean acidification and sea-level
rise. All three are a direct outcome of the atmospheric enrichment of
pollution with greenhouse gases, especially carbon dioxide. To minimize
the risk to the oceans and marine life it will thus be crucial to stem
the increase in atmospheric carbon dioxide in time. WBGU stresses the
need for a rapid response: because of the major time lags, human action
now will determine the state of the oceans for many centuries to come.
Ocean
acidification is advancing
The
carbon dioxide released by human activities not only alters the atmospheric
radiation balance and thus drives climate change. Carbon dioxide also
dissolves directly in seawater. This causes rapid acidification of the
oceans, which is already measurable today. If no action is taken, acidification
could already reach a level within this century that will be greater than
has probably occurred at any time for many millions of years. Furthermore,
this process will be irreversible for a very long period of time. Acidification
presents particular threats to calcifying marine organisms, such as corals,
that have a key function in marine food webs and global biogeochemical
cycles.
Oceans
are warming, sea ice is melting
Warming seawater is threatening numerous marine ecosystems and fish stocks.
This development poses incalculable risks, especially to human food security:
about 15 per cent of the animal protein consumed worldwide derives from
fish. One of the most visible consequences of warming is the retreat of
Arctic sea ice. Over the past 30 years, summertime ice cover has declined
by about 20 per cent. Without action to mitigate climate change, the Arctic
Ocean is projected to be practically ice-free in summer by the end of
the 21st century. This would have far-reaching consequences for climate
worldwide.
The
destructive force of cyclones is mounting
Observations and modelling results indicate that while climate warming
does not increase the total number of tropical cyclones, it gives them
greater destructive force. Tropical sea-surface temperatures have warmed
by only half a degree Celsius, while an increase in the energy of hurricanes
by 70% has been observed.
Sea-level
rise is accelerating
Due to the melting of inland glaciers and continental ice sheets, in combination
with the expansion of seawater that is a direct result of warming, sea
levels are rising. The average global rate of rise throughout the 20th
century was 1.5–2 centimetres per decade. Satellite measurements
show that sea levels have risen by 3 centimetres in the past decade alone.
Should the sea rise by more than 1 metre from the pre-industrial level,
WBGU fears that the adaptive capacity of coastal societies will be overstretched.
WBGU
recommends: Limit acidification and temperature rise
Adaptation measures can only succeed if sea-level rise, ocean warming
and ocean acidification are limited to tolerable levels. The only way
to do this is through aggressive climate protection policies. WBGU has
already recommended previously that the rise in global mean temperature
be limited to a maximum of 2 degrees Celsius above the pre-industrial
level. Ocean conservation is a further reason for imposing this limit.
Furthermore, in order to restrain acidification it is essential to reduce
not only emissions of the overall basket of greenhouse gases, but also
to ensure that carbon dioxide emissions in particular are sufficiently
abated. It follows in WBGU’s view that global anthropogenic greenhouse
gas emissions will need to be approximately halved by 2050 from 1990 levels.
WBGU
recommends: Strengthen the resilience of marine ecosystems
To
strengthen the resilience of marine ecosystems to elevated seawater temperatures
and acidification, it is essential to manage marine resources sustainably.
In particular, over-fishing must be stopped. In addition, WBGU recommends
designating at least 20–30 per cent of the global marine area as
conservation zones. The international community has already adopted goals
in this regard, for instance at the World Summit on Sustainable Development
in Johannesburg. These must now be implemented, and the regulatory gap
for the high seas closed by adopting an appropriate international agreement.
WBGU
recommends: Develop new strategies for coastal protection
About every fifth person lives within 30 kilometres of the sea. Many
of these people are put at immediate risk by sea-level rise and hurricanes.
Coastal protection is thus becoming a key challenge for society, not least
in financial terms. National and international strategies for mitigation
and adaptation need to be further developed and harmonized. This includes
plans for a managed retreat from endangered areas. In developing countries,
financing needs to be secured by means of both existing and innovative
financing instruments such as micro-insurance.
WBGU
recommends: Give legal certainty to refugees from sea-level rise
At present, international law neither establishes a commitment to
receive people who are forced to leave coastal areas or islands because
of climate change, nor is the cost question resolved. Over the long term,
a quota system is conceivable, under which states would have to adopt
responsibility for refugees in line with their greenhouse gas emissions.
This will require formal international agreements and the establishment
of dedicated funds for international compensation payments.
WBGU
recommends: Use carbon dioxide storage only as a transitional solution
To mitigate emissions, carbon dioxide can be captured in energy-generating
facilities and then stored in geological formations on land or under the
sea floor. Direct injection into the deep sea is a further option under
debate, but this lacks permanence and harbours a risk of ecological damage
in the deep sea. WBGU therefore recommends prohibiting the injection of
carbon dioxide into seawater in general. In contrast, storing carbon dioxide
in geological formations under the sea floor can present a transitional
solution for climate protection, complementing more sustainable approaches
such as enhancing energy efficiency and expanding renewable energies.
Permits should only be granted, however, if such storage is environmentally
sound and is secure for at least 10,000 years.
Handing
over the Report
From left
to right: Prof. Dr. Schellnhuber, State Secretary Müller, State Secretary
Rachel, Prof. Dr. Rahmstorf, Prof. Dr. Schulz-Baldes, Prof. Dr. Messner,
Prof. Dr. Schmid.
Please direct your queries to:
WBGU Secretariat
Reichpietschufer 60-62, 8th Floor
D-10785 Berlin
Germany
Tel. +49 30 263948 12
Fax +49 30 263948 50
Email: wbgu@wbgu.de
All press releases and reports can be downloaded
at http://www.wbgu.de.
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