OCEAN ACIDIfication
enhances
GLOBAL temperature rise
compound known as dimethyl sulphide (DMS).
DMS oxidises in the atmosphere to form sulphuric
acid, which become aerosol particles that ‘seed’
clouds and reflect solar radiation away from
the Earth. This process acts as a natural cooling
agent for the Earth’s surface
[2]
.
Scientists hypothesised that an increase in
global temperatures can promote phytoplankton
growth; hence, the production of DMS, and
can potentially help offset global warming.
Recent research, however, showed that an
opposite effect seems more likely. Res
n
Hamburg, Germany numerically modelled the
effect of ocean acidification on DMS production
and global temperatures. Previous mesocosms
studies– enclosed volumes of water – found that
DMS production decreases when reducing water
pH by 0.3 units, matching the predicted level for
2100, based on a “business as usual scenario”.
Under this emission estimation, the heat trapping
gases will increase global temperatures by
2.1 to 4.4°C. Assuming that present-day CO
2
concentration is doubled (a level much less than
what is forecasted by the end of this century),
the team predicts an additional 0.23 to 0.48C
increase in global temperatures. This prediction
highlights a positive feedback between CO
2
emission and further temperature increases
[3]
.
Katharina Six from this team cautioned that
their research is still in its early stages and much
of it is focused on polar and temperate waters.
DMS emi s sions on t ropical and subt ropical
waters have yet to be investigated; dissolution
of CO
2
is not the same in different regions and
bodies of water. Furthermore, extrapolating data
observed in mesocosms over weeks to long-term
system dynamics could be problematic. Future
The
Industrial Revolution has brought
about positive changes to virtually every aspect
of people’s daily lives. However, convenience,
increased life expectancy, and improvements
in the quality of life have come at the enormous
cost of straining the planet’s natural resources.
The dramat i c i ncrease i n ca r bon d i ox i de
emissions from burning fossil fuels, urbanisation
and deforestation, have been identified as
leading causes of global warming
[1]
. Ocean
acidification, a process that raises the acidity
of sur face sea water, due to increased CO
2
emission, has recently been identified as a
wor r y i ng factor i n i ncreas i ng the average
temperature of the planet.
The transfer of gases between the air and
the Earth’s water is a process determined by the
difference in gas concentration between the two
media, and occurs so that an equilibrium can
be reached. An increase of atmospheric CO
2
,
caused by human activities, forces the ocean
to take up more CO
2
. The excess CO
2
hydrates
with seawater, which acts as a buffer, and alters
the carbonate chemistr y through a series of
chemical reactions. As a result, protons increase
and carbonate ions decrease. These changes
in the chemistry of seawater increase acidity
and are termed ‘ocean acidification’. Ocean
acidification is considered one of the greatest
threats to marine ecosystems in the 21
st
century.
The recent work by the German research group
at the Max Planck Institute of Meteorology
highlights a double whammy - acceleration of
global warming through ocean acidification’s
impact on phytoplankton.
Phy toplank ton, are t i ny photosynthet ic
organisms, live in the ocean and emit an organic
