Positive future climate feedback due to changes
in oceanic DMS emissions
OCFUCC INT SCIENT. CONF., PARIS, FRANCE, 7-10 JULY 2015
Jerry Tjiputra1,5, Katharina Six2, Øyvind Seland3, and Christoph Heinze1,4,5
1Uni Research Climate, Bergen, Norway 2Max-Planck-Institute of Meteorology, Hamburg, Germany 3Norwegian meteorological Institute, Oslo, Norway 4University of Bergen, Bergen, Norway 5Bjerknes Centre for Climate Research, Bergen, Norway
DMS
2
Motivations
Modified from Friedlingstein et al. (2006)
COUPLED
UNCOUPLED
Atmospheric CO2 concentration
IPCC-AR4 WG1-Ch.7, Fig 10.20 (2007)
[2.6
– 4
.1°C
] [2
.4 –
5.6
°C]
Additional warming of
0.1 to 1.5 °C
With biogeochemistry
Without biogeochemistry
• Biogeochemical process introduce feedback to future climate change.
3
Motivations
• DMS-climate feedback is currently not included in CMIP5 (IPCC-AR5)
models
• Cloud component in the climate system contributes with the largest source
of uncertainties in future projection (IPCC, 2013).
• Marine dimethylsulphide (DMS) emissions encompass the largest natural
source of atmospheric gaseous sulphur.
• Once released, DMS particles act as CCN, altering cloud composition in
the atmosphere and radiative balance.
• Ocean acidification has been identified to alter DMS production, a potential
additional source of biologically induced feedback on climate.
4
Methods: Norwegian Earth System Model (NorESM1-ME)
CLM-CN
CAM (Atmosphere, ~2°)
CICE
HAMOCC MICOM (Ocean)
~1°, 53L
Atmospheric chemistry
River routing
Sulfur chemistry and
aerosol microphysics
NorESM1-ME model diagram (Bentsen et al., 2013; Tjiputra et al., 2013)
- Fully interactive with prescribed CO2 emissions
- Historical + RCP8.5 scenario (1850-2100)
Marine DMS emissions
5
PO4, NO3, Fe
RC:P N
Phyt oplankt onDiat omsCalcifiers
NPP
Det rit usZooplankton DOC
POC
Chlorophyll
grazing
phot oadapt ion
fecal pellet sexcret ion
bact erial removal
export
& mort alit y
Ocean surface (euphotic layer)
Atmosphere
DMS
Emissions to atmosphere
Six and Maier-Reimer, 2006
Prescribed from
observation
Marine DMS emissions
6
PO4, NO3, Fe
RC:P N
Phyt oplankt onDiat omsCalcifiers
NPP
Det rit usZooplankton DOC
POC
Chlorophyll
grazing
phot oadapt ion
fecal pellet sexcret ion
bact erial removal
export
& mort alit y
Ocean surface (euphotic layer)
Atmosphere
DMS Bacterial
activity
Photolysis
loss
Emissions to atmosphere
Six and Maier-Reimer, 2006
Climate feedback
Ocean acidification
feedback
Processes influence the DMS emissions and feedback
7
• Ocean circulation/upwelling: nutrient availability
• Sea-ice variations: irradiation
• Warming: phytoplankton growth period
• Ocean acidification: DMS production rate
Bopp et al. (2013)
Six et al. (2013)
Validation of annual DMS concentrations and emissions
8
Concentr
ation
E
mis
sio
ns
Observation (Lana et al., 2010) Model
Global annual emissions:
- Prescribed: 18. Tg S
- Interactive: 25. Tg S
- Obs: 17-34 Tg S
Experiment configurations
9
Historical + future scenario RCP8.5 simulations:
• Reference -> no interactive DMS (prescribes DMS concentration)
• Clim -> consider only climate change impact on DMS production
• Clim+pH -> climate change impact and acidification
Clim_pH
NPP pH REF
Clim
Temperature, wind-speed,
sea-ice, circulations, etc.
Projected regional change in DMS emissions
11
Regional changes relative to the preindustrial fluxes (1850s)
Reduce Increase
30-40%
decrease
Projected regional change in DMS emissions
12
+200%
+90%
-40%
-30%
-12%
+4%
Climate change induces heterogeneous regional effect on net primary production
Ocean acidification leads to reduction in DMS emissions (largest at high latitudes)
Projected regional change in mean surface air temperature
14
Projected ∆T (by end of 21st century) is
similar between all experiments (REF,
Clim, and Clim+pH)
When acidification effect is considered,
additional warming as much as 4K are
simulated in the Arctic and Antarctic
Additional temperature change due to DMS-climate feedback
15
pH-effect on DMS production induces additional warming in majority of Earth’s surface,
particularly in the high latitude, potentially due to polar amplification
Summary
17
• Oceanic DMS emission is projected to decrease in low- and mid-latitudes, attributed to
climate change (reduction in net primary production).
• In high latitude, warming (higher phytoplankton growth rate) and retreat of sea-ice lead
to increase in DMS outgassing.
• Future ocean acidification broadly decreases the DMS emissions.
• Globally, DMS is projected to introduce additional positive climate feedback.
• The mean global surface temperature at the end of 21st century is projected to be
warmer by approximately 0.4K compare to the simulation without DMS.
• Regionally, as much as 4K additional warming is projected, e.g., in the Arctic.
Funding acknowledged: NFR-EVA (no229771)
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