Geoscience Reference
In-Depth Information
indicating vulnerability of the Arctic and coastal
upwelling to carbonate undersaturation, further
work highlighting the vulnerability of corals to
decreasing CaCO
3
saturation and other experimen-
tal evidence increasingly revealing that juveniles,
reproduction, physiology etc. of different organ-
isms are vulnerable to ocean acidii cation, even if
adults are not. There are papers with conl icting
results which are being debated in the literature.
The great majority of the growing evidence from
i eld work, experiments, modelling, and the geo-
logical record indicates that the consequences for
the future could be very serious, but there are still
substantial knowledge gaps which together sup-
port the continued 'medium rating' (e.g. Kroeker
et al.
2010). Even more uncertain are the biogeo-
chemical impacts and impacts on food webs and
ecosystems. This is due partly to a lack of research
in the area but also due to increasing uncertainty
with the complexity of marine systems. Thus, in
terms of our understanding of the future impacts of
ocean acidii cation there currently seems to be a
gradient of certainty based on evidence from chem-
istry at the high-certainty end of the range to indi-
vidual organisms with medium certainty, but as we
move through populations, food webs, and ecosys-
tems to biogeochemistry, the certainty is reduced.
However, despite this uncertainty, expert opinion is
generally that there is real concern that ecosystems
(such as tropical coral reefs, cold-water coral com-
munities, and polar ecosystems) or biogeochemical
cycles could be at risk within this century if CO
2
emissions continue unabated (see Chapter 15).
global scale is to reduce CO
2
emissions to the atmos-
phere. However, there are other hazards to coral
reefs such as coastal development, pollution, and
overi shing that may amplify their vulnerability
(IPCC 2007). Averting potential changes to major
marine ecosystems such as coral reefs, that harbour
great biodiversity, protect coastlines, and provide
livelihoods and food for millions, may or may not be
sufi cient argument for mitigation and will depend
on international politics and the proportionality
(and cost) of proposed solutions. Policymakers will
need to know the answers to a number of complex
questions that have socio-economic relevance. If the
non-CO
2
-related hazards are removed, will that ena-
ble reefs to survive at higher CO
2
levels? What level
of CO
2
will be safe for corals? If society invests in
low-carbon energies and technology and reduces
CO
2
emissions what will it gain for its effort? So, if
CO
2
emissions peak at 550 ppmv then what propor-
tion of the world's coral reefs will remain, what will
their quality be, and which corals will survive? If
CO
2
emissions are reduced even further, with a peak
at 450 ppmv, what will be the further advantage in
terms of the proportion, quality, and geographical
distribution of surviving reefs? Are there 'tipping
points' in ocean acidii cation which should be
avoided? What are the costs and benei ts or the
risk:reward ratio of action to prevent and/or miti-
gate ocean acidii cation?
Such policy-relevant questions like these may not
be in the mind of many i eld- or laboratory-based
scientists, unless they have a close working
relationship with those who inl uence policy.
That is why there is a need for very close communi-
cation and understanding between scientists and
policymakers.
13.5.6 Risk and applying the precautionary
principle
The nature of a risk is important in assessing
whether society should act and apply the precau-
tionary principle to reduce it. In the case of ocean
acidii cation, the hazard is caused by increasing
CO
2
emissions in the future. This CO
2
is also caus-
ing another hazard to coral reefs through warming
surface seawater which can cause coral bleaching.
These two hazards may occur at the same time and
therefore represent a greater risk than either on
their own. Scientii c evidence to date indicates that
the only way to reduce these specii c hazards on a
13.6 Wider communication of ocean
acidii cation
13.6.1
Communicating with stakeholders
In 2004, an ocean acidii cation RUG of key stake-
holders was set up to run alongside the scientii c
research in the UK project 'Impact of CO
2
on Marine
Organisms' (IMCO2, 2004-2008). In 2008, the RUG
was further developed as part of the EU funded
EPOCA programme. In 2010, the RUG further
