Svein Sundby
Biogeochemical cycles and sustainable pathways
in the ocean, atmosphere and land
IGBP Symposium, Bergen, 24 May 2012
The microscopic marine
plants
Phytoplankton production
At large scales spatial
distribution and abundance
across trophic levels are correlated
Zooplankton production
Fish catches
Pinet (2006)
Phytoplankton concentrations of the world’s oceans
display distinct spatial patterns
Globally modeled phytoplankton production
(average of a group of four global models)
Pre-industrial production
(1860s)
Change in production at
the end of this century
(2090s)
Steinacher et al. (2010) Biogeosciences
World oceans major biomes
Arctic
High latitude
spring-blooms
Semi-enclosed seas
EBUE
Oligotrophic gyres
WBE
Equatorial upw.
Oligotrophic gyres
EBUE
WBE
Equatorial upw.
Oligotrophic gyres
EBUE
EBUE
High latitude spring-blooms
Antarctic
WBE
LIGHT
latitude, season, clouds
1
PHOTIC ZONE
10-100 m
3
TEMPERATURE
NUTRIENT
RECYCLING
zooplankton
phytoplankton
microbes
temperature
2
NUTRIENTS
&
MICRONUTRIENTS
upwelling, vertical mixing
FACTORS DETERMINING PHYTOPLANKTON
PRODUCTION & DYNAMICS
Productivity in the oligotrophic gyres limited by
the thermal stratification
Low-productive
oligotrophic ocean-gyre
ecosystems
LIGHT
latitude, season, clouds
1
PHOTIC ZONE
10-100 m
3
TEMPERATURE
NUTRIENT
RECYCLING
zooplankton
phytoplankton
microbes
temperature
2
NUTRIENTS
&
MICRONUTRIENTS
upwelling, vertical mixing
GLOBAL CLIMATE CHANGE:
PRODUCTION DECREASING BY REDUCED
NUTRIENT SUPPLY FROM DEEPER WATER
Walvis Bay
Benguela
upwelling
system –
Namibia
South Africa
Cape Town
Forced by the
southeasterly
winds
- and wind forcing has increased in all the four large upwelling
ecosystems since 1960
Narayan et al. (2010)
Eastern Boundary
Upwelling
Ecosystem
LIGHT
latitude, season, clouds
1
PHOTIC ZONE
10-100 m
3
TEMPERATURE
NUTRIENT
RECYCLING
zooplankton
phytoplankton
microbes
temperature
2
NUTRIENTS
&
MICRONUTRIENTS
upwelling, vertical mixing
GLOBAL CLIMATE CHANGE:
PRODUCTION ENHANCED BY INCREASED
UPWELLING WINDS
High-latitude
spring-bloom
ecosystem
LIGHT
latitude, season, clouds
+
less ice cover
1
PHOTIC ZONE
10-100 m
3
TEMPERATURE
NUTRIENT
RECYCLING
zooplankton
phytoplankton
microbes
temperature
2
NUTRIENTS
&
MICRONUTRIENTS
upwelling, vertical mixing
GLOBAL CLIMATE CHANGE:
PRODUCTION ENHANCED BY INCREASED
REGENERATED PRODUCTION
AND REDUCED ICE COVER
19.5 % of the world’s ocean area
80 % of the world’s fish catches
• Impacts of climate change on marine ecosystems is
not uniform but varies depending on the critical physical
and biological mechanisms
• High-latitude and upwelling ecosystems have the
potential of higher production under climate change
• Low-latitude and mid-ocean gyre ecosystems will most
probably decrease the productivity under climate change