acidification: Royal Society Report
The Royal Society released its report on ocean
acidification on 30/6/2005.
Membership of Royal Society working group:
Professor John Raven FRS, University of Dundee (Chair)
Dr Ken Caldeira, Lawrence Livermore National Laboratory, USA
Prof Harry Elderfield FRS, University of Cambridge, UK
Prof Ove Hoegh-Guldberg, University of Queensland, Australia
Prof Peter Liss, University of East Anglia
Prof Ulf Riebesell, Leibniz Institute of Marine Sciences, Germany
Prof John Shepherd FRS, Southampton Oceanography Centre, University of
Dr Carol Turley, Plymouth Marine Laboratory
Prof Andrew Watson FRS, University of East Anglia
The full report is available from the
Royal Society's website: www.royalsoc.ac.uk.
Citation: Royal Society (2005) Ocean
acidification due to increasing atmospheric carbon dioxide. The Royal
PRESS RELEASE: (30 June 2005)
Cuts in carbon dioxide emissions vital to stem rising
acidity of oceans says
Cuts in emissions of the greenhouse gas carbon dioxide are the only way
stem the rising levels of acidity in our oceans and prevent potentially
damaging consequences for marine life, warns a new report published by
Royal Society today (Thursday, 30 June 2005).
According to the report, ocean acidification due to increasing
carbon dioxide, excess carbon dioxide in the atmosphere, from man's
of fossil fuels, has already increased the acidity of the world's oceans
a level that is irreversible in our life times. This is because the
oceans act as a sponge, taking up carbon dioxide from the atmosphere
dissolves and forms an acid in the seawater.
Professor John Raven, chair of the Royal Society working group on ocean
acidification said: "Along with climate change, the rising acidity
oceans is yet another reason for us to be concerned about the carbon
we are pumping into the atmosphere. Our world leaders meeting at next
G8 summit must commit to taking decisive and significant action to cut
carbon dioxide emissions. Failure to do so may mean that there is no
in the oceans of the future for many of the species and ecosystems that
know today. "
Sea creatures such as corals, shell fish, sea urchins and star fish are
likely to suffer the most because higher levels of acidity makes it
difficult for them to form and maintain their hard calcium carbonate
skeletons and shells. For example, even under the 'low' predictions for
future carbon dioxide emissions into the atmosphere, the combined
climate change and ocean acidification mean that corals could be rare on
tropical and subtropical reefs, such as the Great Barrier Reef, by 2050.
This will have major ramifications for hundreds of thousands of other
species that dwell in the reefs as well as for the people that depend
them, both for food and to help to protect coastal areas from, for
The report says that changes in ocean chemistry, caused by ocean
acidification, means that we can predict that some creatures in the
Antarctic Ocean will be among the first to be affected. For example,
types of plankton - a major source of food for fish and other animals -
be unable to make their calcium carbonate shells by 2100. This may have
significant consequences for entire food webs in the region, although
overall impact of this is unclear.
Higher concentrations of carbon dioxide may also make it harder for some
larger marine animals to obtain oxygen from seawater. For example, squid
particularly sensitive because they move by jet propulsion - this is
energy-demanding and requires a good supply of oxygen.
Professor Raven said: "Basic chemistry leaves us in little doubt
burning of fossil fuels is changing the acidity of our oceans. And the
change we are seeing to the ocean's chemistry is a hundred times faster
has happened for millions of years. We just do not know whether marine
- which is already under threat from climate change - can adapt to these
By absorbing carbon dioxide the oceans actually help stave off climate
change. In the past 200 years the oceans have absorbed about half of the
carbon dioxide produced by humans, primarily through the burning of
fuels. They are currently taking up one tonne of this carbon dioxide for
each person on the planet every year.
However, the report warns that rising levels of acidity in the ocean may
mean that the ability of the oceans to mop up carbon dioxide from the
atmosphere will be reduced. This is because the chemistry of the surface
waters of the ocean means that as carbon dioxide is added, its ability
take up more is decreased. Furthermore, any rise in ocean temperatures,
to climate change, could reduce the ability of the surface waters to
carbon dioxide from the atmosphere.
Professor Raven said: "The oceans play a vital role in the earth's
and other natural systems which are all interconnected. By blindly
with one part of this complex mechanism, we run the risk of unwittingly
triggering far reaching effects."
The report looks at various ways of tackling rising acidity such as
limestone to the oceans to make them more alkaline. However, it found
the only practical way to minimise the risk to the oceans and marine
to reduce emissions of carbon dioxide into the atmosphere.
The report point out that there is still much uncertainty around the
of ocean acidification and recommends that a major international effort
launched into this relatively new area of research.
Conclusions and recommendations of the report
1. The oceans are absorbing CO2 produced
from human activities from the
atmosphere and this is causing chemical changes in the oceans by making
more acidic (i.e., decreasing the pH of the oceans).
a. Ocean acidification, like global
warming, is a predictable response
to those human activities that increase the atmospheric concentration of
CO2. The magnitude and rate of the acidification of the oceans can be
predicted with more confidence than the rise in temperature due to
warming, as they are less dependent on climate-system feedbacks.
b. Predictions of the consequences of CO2
emissions must take into
consideration the close chemical and physical coupling between the
and the atmosphere. For example, changes in the chemistry of the ocean
affect its ability to absorb additional CO2, which will in turn affect
rate and scale of global warming. Rising sea temperatures caused by
warming also affect ocean chemistry, as well as other physical and
c. The oceans are currently taking up
about 1^tonne of human-derived
CO2 per year for each person on the planet. Almost a half of the CO2
produced in the past 200 years from burning fossil fuels and cement
manufacture has been absorbed by the oceans. Calculations based on
measurements of the surface oceans and our understanding of ocean
indicate that this uptake of C02 has already reduced surface
by about 0.1, which corresponds to an increase of about 30% in the
concentration of hydrogen ions.
d. As CO2 continues to enter the
atmosphere from human activity, a
proportion will be taken up by the oceans. If CO2 emissions are not
regulated, this could probably result in the pH decreasing by a further
units below 2000 levels, by 2100; this is beyond the range of current
natural variability and probably to a level not experienced for at least
hundreds of thousands of years and possibly much longer. Critically, the
rate of change is also probably at least 100 times higher than the
rate observed during this time period.. These changes are so rapid that
are overwhelming the buffering capacity of the natural processes that
moderated changes in ocean chemistry over most of geological time.
e. The chemical changes in the oceans
caused by increases in the
concentration of CO2 in the atmosphere will include a lowering of the
increase in dissolved CO2, a reduction in the concentration of carbonate
ions, and an increase in bicarbonate ions. All of these will affect the
organisms and processes in the ocean.
f. There appears to be no practical way to
remove this additional CO2
from the oceans after it has been absorbed, nor any realistic way to
its widespread chemical and biological effects. It will take many
of years for natural processes to remove this excess CO2 and return to a
level close to their pre-industrial state. Thus, it appears that the
practical way to minimise long-term consequences for the oceans is to
CO2 emissions to the atmosphere.
2. These changes in ocean chemistry will
impact on marine organisms and
a. Seawater pH is a critical variable in
marine systems; even small
changes will have a large impact on ocean chemistry. These changes are
likely to change the biodiversity of marine ecosystems, and may affect
total productivity of the ocean. The impacts will be greater for some
regions and ecosystems. However, apart from a few ecosystems such as
reefs and the Southern Ocean, the direction and magnitude of these
are very uncertain. Most of the available evidence suggests that these
changes are likely to reduce the resilience of marine ecosystems.
b. The best scientific information
currently available suggests that
these changes in ocean chemistry will almost certainly have major
effects on corals and the reefs they build in tropical and subtropical
waters. This will affect the stability and longevity of the structures
supporting these ecosystems with implications for the biodiversity and
ecological sustainability. Cold-water coral reefs are also likely to be
c. Future concentrations of the carbonate
ion are likely to fall to
levels that will make it more difficult for animals to produce hard
structures such as carbonate skeletons and shells. The evidence
suggests that this will probably adversely affect most of these
For example many coastal animals and specific groups of phytoplankton
zooplankton will be affected.
d. Increased CO2 and the associated
reduction in seawater pH may be
particularly stressful for organisms with high metabolism such as squid.
Whilst the physiology of other large marine animals will also be
possibly restricting their growth, reproduction or both
e. Benthic ecosystems, especially on the
seabed of shallow waters,
provide an essential service for other organisms in the surface oceans:
receiving food from the sunlit waters above in the form of sinking
particles, they also recycle nutrients from the sediments, which are
required for the growth of other organisms. Differences in the response
these diverse organisms to reduced pH could have a considerable impact
the functioning of marine sediments and the 'ecosystem goods and
f. Organisms will continue to live in the
ocean wherever nutrients and
light are available, even with ocean acidification. However, from the
available, it is not known if organisms at the various levels in the
web will be able to adapt or if one species will replace another. It is
not possible to predict what impacts this will have on the community
structure and ultimately if it will affect the services that the
provide. Without significant action to reduce CO2 emissions into the
atmosphere, this may mean that there will be no place in the future
for many of the species and ecosystems that we know today.
3. Oceans play a very important role in
the global carbon cycle and
Earth's climate system.
a. There are potentially important
interactions between changes in the
state of the oceans (including its pH) and changes in the global climate
atmospheric chemistry. Our knowledge of these impacts and effects is
currently poor and requires urgent consideration.
b. In addition to ocean acidification
climate change - a better known
effect of increasing atmospheric C02 emissions - will also affect marine
ecosystems. Occurring at the same time, these effects, particularly of
increased ocean temperature, will be additional to (and possibly
with) those due to increased CO2 and acidification.
4. The socio-economic effects of ocean
acidification could be
a. Serious damage to coral reef
ecosystems, and the human activities
that are based on them such as fisheries and recreation, could amount to
economic losses of many billions of dollars per year. This will have
serious impacts on the vulnerable societies that depend upon them.
b. Ocean acidification is likely to have
significant impacts on some
marine fish and shellfish species. The economic value of many of these
impacts cannot be determined, but would present a risk to some unknown
fraction of the global economic value of these resources (about $100
c. Ocean acidification will probably cause
significant changes in the
whole marine biogeochemical system and the ecosystem services that it
provides, to an extent and in ways that cannot at present be foreseen.
d. Changes to the stability of coastal
reefs in tropical and
subtropical parts of the globe may lead to serious decreases in coastal
protection over longer time periods. These changes could fundamentally
change the nature of entire coastlines and the resources available to
societies that depend on them.
5. Reducing the scale of future changes to
the chemistry and acidity of
the oceans is only possible by preventing the accumulation of CO2 in the
a. Solutions other than preventing CO2
emissions reaching the
atmosphere, such as adding chemicals to counter the effects of
acidification, are likely to be only partly effective and only at a very
local scale. It would be impossible at a regional or global level, and
also cause damage to the marine environment.
b. There are many possible approaches to
preventing the accumulation in
the atmosphere of CO2 produced by human activities: for example,
energy efficiency, use of renewable energy, and carbon sequestration in
geological reservoirs. However, some approaches, such as direct
CO2 into the deep ocean, have the potential to further exacerbate
changes to the ocean.
c. Unless significant reductions are made
to the rate of emissions of
CO2 into the atmosphere (to less than those leading to a doubling from
current atmospheric CO2 concentrations by 2100 ) the entire depth of the
Southern Ocean will become under-saturated for aragonite, which is
by some organisms to make carbonate skeletons and shells. Further
in atmospheric concentration of CO2, above this doubling, would make the
impacts progressively worse for the ocean as a whole.
6. We conclude on the basis of current
evidence and that acidification
of the oceans, caused by emissions of CO2 into the atmosphere, is
inevitable, and the magnitude of this acidification can be predicted
high level of confidence. However, its impacts, particularly on marine
organisms, are much less certain and require a substantial research
a. Research into the impacts of an ocean
with a high CO2 concentration
is in its infancy and needs to be developed rapidly. Among the priority
areas for further research are the identification of those species,
functional groups and ecosystems that are most sensitive to, and the
which organisms can adapt to, increased surface ocean CO2; the
of increased CO2 in the surface ocean with other factors such as
temperature, with the carbon cycle, with sediment processes, and with
balance of reef accretion and erosion; feedbacks of increased ocean
CO2 on air-sea exchange of CO2, DMS and other gases important for
and air quality; and larger-scale manipulation experiments on the effect
increased CO2 on biota in the surface ocean.
7. Ocean acidification is a powerful
reason, in addition to that of
climate change, for reducing global CO2 emissions.
1. There is a clear risk of significant
adverse effects from ocean
acidification. We recommend that this should be taken into account by
makers and other relevant national and international bodies (perhaps
including the United Nations Framework Convention on Climate Change) at
discussions and negotiations about climate and other global changes.
2. Any targets set for CO2 emission
reductions should take account of
the impact on ocean chemistry and acidification as well as climate
We recommend that if the risk of irreversible damage arising from ocean
acidification is to be avoided, the cumulative future man-made emissions
CO2 to the atmosphere should be less than 900^Gt^C by 2100 (2100). Even
this level the direct impact of ocean acidification, is very likely to
serious harm to the Southern Ocean.
3. Ocean acidification and its impacts on
the oceans needs to be taken
into account by the Intergovernmental Panel on Climate Change and kept
review by international scientific bodies such as the Intergovernmental
Oceanic Commission, the Scientific Committee on Oceanic Research and the
International Geosphere-Biosphere Programme.
4. Tackling ocean acidification cannot be
done by any country alone. We
believe that the UK could and should take a lead internationally on both
policy and research. However, it will only be able to do so by
and extending its research activity and its international scientific
5. Marine ecosystems are likely to become
less robust as a result of
the changes to the atmosphere outlined in this report and are likely to
more vulnerable to other environmental impacts (for example climate
water quality, coastal deforestation fisheries and pollution). This
increased fragility and sensitivity of marine ecosystems needs to be
into consideration during the development of any policies that relate to
their conservation, sustainable use and exploitation, or effects on the
communities that depend on them.
6. Research into ocean chemical changes
needs additional investment.
Given the potential impacts, we recommend that a major internationally
coordinated research effort (including monitoring) should be launched.
scale of this needs to be commensurate with that on the effects of
change arising from enhanced greenhouse emissions. The impacts of ocean
acidification are additional to, and may exacerbate, the effects of
change. For this reason, the necessary funding should be additional and
not be diverted from research into climate change.
International collaboration should be enhanced, particularly on the
questions associated with effects on ocean chemistry and impacts on
sensitive organisms, functional groups and ecosystems. These efforts
focus on establishing a better understanding of the various metabolic
processes at different parts of the life cycle and how these are
at an ecosystem level. Approaches required include global monitoring,
experimental, mesocosm and field studies, and models that include
pH on scales ranging from that of the organism to that of the ecosystem.
Greater understanding of the likely changes will help inform the
strategies by which human populations can mitigate or adapt to these
changes, and can also be linked to climate change models to predict
synergistic impacts. The existing research projects of Surface
Atmosphere Study (SOLAS) and Integrated Marine Biogeochemistry and
Research Project (IMBER) should be part of any new initiative.
7. Action needs to be taken now to reduce
global emissions of CO2 to
the atmosphere to avoid the risk of large and irreversible damage to the
oceans. We recommend that all possible approaches be considered to
CO2 reaching the atmosphere. No option that can make a significant
contribution should be dismissed.