www.bjerknes.uib.no
MERCLIM
Carbon cycle and changes in ocean
chemistry and assessment of possible
impacts.
Richard Bellerby
Bjerknes Centre for Climate Research,
University of Bergen
IPCC
2100
2200
Adapted from a figure by Christoph Heinze
Ocean acidification is the transformation of
seawater towards an acidic state – it does not
mean that the oceans will become acidic
Today’s ocean pH is
already below the
glacial-interglacial
range
IMBER, 2005
Nordic
Seas
Ocean
depth
Atlantic anthropogenic carbon
distribution
Vázquez Rodríguez et al 2009
Global ocean acidification from observations
Nordic Seas (1981-2004)
Southern Ocean:
Weddell sea (1992-2008)
Adapted from Olsen et al, GBC, 2006
Hauck et al., JGR Oceans, 2010
Surface ocean pH reduction over this century
will exhibit large regional variability
Reductions in pH throughout this century will be greatest in the Arctic
Larger
Change in surface
ocean pH in the
21st Century
Large
Bellerby, et al, 2005.
and NORACIA 2010
Climate change scenarios of CaCO3 saturation
aragonite
2059
Exploring ecosystem and biogeochemical feedbacks to
ocean acidification
University of Bergen Mesocosm facilities
Reduced (but possible) calcium carbonate production in a
high CO2 ocean
Increasing CO2
Glacial
Present Future
Day
(2100)
Delille et al GBC, 2005
Lessons from the past 55 million years ago?
Massive changes in biogeochemical cycling and ecosystem
structure – large scale extinction and radiation of new species
Increasing ocean acidification
Years (1000s)
after release
CO2 release
No CaCO3
Start of CO2
increase
High
CaCO3
Zachos et al. 2005
Direct evidence from experimenal work
- An enhanced biological carbon pump in a
high CO2 ocean?
Atmospheric CO2 scenario
Present
370
ppm CO2
750
ppm CO2
2100
1050
ppm CO2
2200
Redfield
”Redfield”
Stoichiometry
Bellerby et al., 2008
Feedbacks to a high CO2 world through changes to
the ”Redfield” ratio of organic matter
Increased biological carbon
consumption may have already
increased the oceanic uptake CO2
and this may continue with
increasing acidification
It has the potential to significantly
reduce future atmospheric CO2
Riebesell et al. Nature, 2007
MERCLIM
First ever large scale polar arctic Ocean Acidification
experiment – Ny Ålesund, Svalbard, May-July 2010
• How will biogeochemical cycling and climate feedback change?
• What are the tipping points for organisms and ecosystems?
MERCLIM
10 nations participated in the Ny Ålesund experiment
Bjerknes Centre was critical for this experiment:
- leading Norwegian participant
- defining the CO2 system
- leading the ocean acidification measurements
Working with the State Key Laboratory of Environmental
Science, Xiamen University (Dr Ray Zhang)
Summary
Ocean acidification is already happening as confirmed by
direct ocean observations
Ocean acidification will be on a global scale with the
greatest and earliest pan-ocean changes seen in the
Arctic albeit with very great variability in regionality
and rates
There are great regional differences seen in the rate of
ocean acidification requiring focussed observational and
modelling strategies.
Large changes in ecological and biogeochemical marine
systems are seen under experiments with increased
ocean acidification