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Marine biology and geochemistry in Earth System Models Andrew Watson School of Environmental Science University of East Anglia Norwich NR4 7TJ UK. Major effects of marine biology on the Earth system. . “Biological pump” for atmospheric CO 2

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Slide1 l.jpg

Marine biology and geochemistry in Earth System Models

Andrew Watson

School of Environmental Science

University of East Anglia

Norwich NR4 7TJ

UK


Major effects of marine biology on the earth system l.jpg
Major effects of marine biology on the Earth system.

  • “Biological pump” for atmospheric CO2

    - sets natural atmospheric CO2 on time scales 102 – 105 years.

  • Sulphur gas impact on cloud albedo via CCN production.

  • Production of sediments – carbonate sink and organic carbon sink.

    • Major influence on atmospheric CO2 and O2 over millions of years.


Why do you need biology and geochemistry in earth system models l.jpg
Why do you need biology and geochemistry in earth system models?

  • Studies of the long-term habitability of the earth:

    • Faint young sun

    • major glaciations

    • Sudden warmings

    • Response to major impact events


The dim young sun evolution of atmosphere and solar output l.jpg

Solar output models?

Atmosphericgreenhouse

surface temperature

The Dim young sun: evolution of atmosphere and solar output

time


Slide6 l.jpg

Weathering of rock: models?

CO2 + XSiO3= XCO3+SiO2

Weathering of organics:

CH2O+O2 = CO2 + H2O

Burial of organics:

CO2 + H2O = CH2O+O2

Ocean

Oceanic crust

Metamorphism of rock;

XCO3+SiO2=CO2 +XSiO3

Weathered sediment from continents

Long term (>105 year) concentrations of atmospheric CO2, O2, CH4 etc are set by biota-geochemical interactions.


Major glaciations l.jpg

Quaternary models?

Permo-Carboniferous

Ordovician

Neoproterozoic

Paleoproterozoic

Major glaciations

  • Some (or all?) may be related to changes in greenhouse gases, driven by biological change.


Slide8 l.jpg

A Neoproterozoic models?

Snowball Earth?


Why do you need marine biology and geochemistry in earth system models l.jpg
Why do you need marine biology and geochemistry in earth system models?

  • Studies of the long-term habitability of the earth

  • The Quaternary climate: the classic Earth system problem.

    • CO2 changes are largely ocean-driven.

    • Cannot be correctly modelled without representation of

      • short-term processes (e.g. air-sea exchange

      • Long-term processes (sedimentary accumulation and dissolution).


Vostok core proxies l.jpg

CO system models?2: controlled by

ocean chemistry,

biology,circulation?

Deuterium

in ice: proxy for

local temperature

Vostok core proxies

Methane:sourced

from wetlands?

Atmospheric dust:

signal “leads” other

indicators

Sea-salt sodium:

proxy for

wind strength?

Atmospheric d18O:

proxy for biosphere

productivity?

The driver?

Summertime

insolation,

N. hemisphere

Source: Petit, J.R. et al., 1999. Nature,399: 429-436.


Why do you need marine biology and geochemistry in earth system models11 l.jpg
Why do you need marine biology and geochemistry in earth system models?

  • Studies of the long-term habitability of the earth

  • The Quaternary climate: the classic Earth system problem.

  • Short term (~100 year) feedbacks on global change…


Possible marine biological effects on carbon uptake next 100 years l.jpg
Possible Marine biological effects on carbon uptake, next 100 years.

Process Effect on CO2 uptake

  • Iron fertilisation or change in atmospheric iron supply.

  • NO3 fertilisation

  • pH change mediates against calcite-precipitating organisms

  • Reduction in overturning circulation interaction with nutrient utilisation

  • Other unforeseen ecosystem changes

?


Modelling the marine ecosystem in esms l.jpg
Modelling the marine ecosystem in ESMs 100 years.

  • Complex ecosystem – too costly (and not enough knowledge) to model at species level.

  • Simple models, “NPZD” – single nutrient, primary producer, consumer.

  • More complex, “functional groups” of phytoplankton, size classes of zooplankton.


Biogeochemical functional groups l.jpg
Biogeochemical 100 years.functional groups

  • Nutrients

    • NO3, PO4, Si, Fe

  • Phytoplankton Fix carbon

    • Diatoms “large”, need Fe, NO3, Si.

    • Non-Diatoms “small”, need Fe, NO3

      • Coccolithophores produce CaCO3

      • Phaeocystis produce DMS

      • Others

  • Zooplankton

    • Mesozooplankton Eat everything, produce large sinking flux

    • Microzooplankton Eat small phytoplankton, produce small sinking flux

  • Bacteria

  • Viruses


Biogeochemical functional groups15 l.jpg

10 100 years.m

Biogeochemical functional groups

  • Nutrients

    • NO3, PO4, Si, Fe

  • Phytoplankton Fix carbon

    • Diatoms “large”, need Fe, NO3, Si.

    • Non-Diatoms “small”, need lower Fe, NO3

      • Coccolithophores produce CaCO3

      • Phaeocystis produce DMS

      • Others

  • Zooplankton

    • Mesozooplankton Eat everything, produce large sinking flux

    • Microzooplankton Eat small phytoplankton, produce small sinking flux

  • Bacteria

  • Viruses


Biogeochemical functional groups16 l.jpg

10 100 years.m

Biogeochemical functional groups

  • Nutrients

    • NO3, PO4, Si, Fe

  • Phytoplankton Fix carbon

    • Diatoms “large”, need Fe, NO3, Si.

    • Non-Diatoms “small”, need Fe, NO3

      • Coccolithophores produce CaCO3

      • Phaeocystis produce DMS

      • Others

  • Zooplankton

    • Mesozooplankton Eat everything, produce large sinking flux

    • Microzooplankton Eat small phytoplankton, produce small sinking flux

  • Bacteria

  • Viruses


Biogeochemical functional groups17 l.jpg

10 100 years.m

Biogeochemical functional groups

  • Nutrients

    • NO3, PO4, Si, Fe

  • Phytoplankton Fix carbon

    • Diatoms “large”, need Fe, NO3, Si.

    • Non-Diatoms “small”, need Fe, NO3

      • Coccolithophores produce CaCO3

      • Phaeocystis produce DMS

      • Others

  • Zooplankton

    • Mesozooplankton Eat everything, produce large sinking flux

    • Microzooplankton Eat small phytoplankton, produce small sinking flux

  • Bacteria

  • Viruses


Biogeochemical functional groups18 l.jpg

10 100 years.m

Biogeochemical functional groups

  • Nutrients

    • NO3, PO4, Si, Fe

  • Phytoplankton Fix carbon

    • Diatoms “large”, need Fe, NO3, Si.

    • Non-Diatoms “small”, need Fe, NO3

      • Coccolithophores produce CaCO3

      • Phaeocystis produce DMS

      • Others

  • Zooplankton

    • Mesozooplankton Eat everything, produce large sinking flux

    • Microzooplankton Eat small phytoplankton, produce small sinking flux

  • Bacteria

  • Viruses


Biogeochemical functional groups19 l.jpg

10 100 years.m

Biogeochemical functional groups

  • Nutrients

    • NO3, PO4, Si, Fe

  • Phytoplankton Fix carbon

    • Diatoms “large”, need Fe, NO3, Si.

    • Non-Diatoms “small”, need Fe, NO3

      • Coccolithophores produce CaCO3

      • Phaeocystis produce DMS

      • Others

  • Zooplankton

    • Mesozooplankton Eat everything, produce large sinking flux

    • Microzooplankton Eat small phytoplankton, produce small sinking flux

  • Bacteria

  • Viruses


Biogeochemical functional groups20 l.jpg
Biogeochemical 100 years.functional groups

  • Nutrients

    • NO3, PO4, Si, Fe

  • Phytoplankton Fix carbon

    • Diatoms “large”, need Fe, NO3, Si.

    • Non-Diatoms “small”, need Fe, NO3

      • Coccolithophores produce CaCO3

      • Phaeocystis produce DMS

      • Others

  • Zooplankton

    • Mesozooplankton Eat everything, produce large sinking flux

    • Microzooplankton Eat small phytoplankton, produce small sinking flux

  • Bacteria

  • Viruses


Slide21 l.jpg

Nitrate concentrations in surface water – the “HNLC” regions

Annual mean surface nitrate, mol kg-1



Slide23 l.jpg

In all the HNLC regions, regions

iron release experiments have now shown that diatom blooms are stimulated by addition of iron. These depress surface CO2 and nutrients.

Why? Large cells such as diatoms have small surface-to-volume ratio. Their growth is limited at low Fe concentrations by rate of diffusive transport of Fe into the cell.


Slide24 l.jpg

Effect of iron on HNLC ecosystems regions

Large-cell system

small-cell system

-inefficient recycling

-efficient recycling

-substantial export

-little particle export

Strongly iron-limited

Weakly iron-limited

"large"

"small"

phyto-

phyto-

plankton

plankton

nut-

rients

meso-

micro-

zoo-

zoo-

plankton

plankton


Slide25 l.jpg

gas regions

exchange

remineralization

Two-component plankton biogeochemistry – BIOGEM (Ridgwell)

aeolian

dust

deposition

e

temperature

+

insolation

dissolution

atmospher

un-off

non-diatom

diatom

r

productivity

productivity

ocean

surface

continental

scavenging

ior

inter

dissolution

ocean

sedimentation

sedimentary

diagenesis

sediments

burial

Fe

C

dust

KEY:

CaCO

PO

Si

3

4



Dust marine biology co 2 climate feedback in the earth system l.jpg
Dust/marine biology/CO regions2 climate feedback in the earth system.


F 1 temperature dust l.jpg
f regions1 : temperature  dust

Data from the Vostok ice core.


F 2 dust atmospheric co 2 l.jpg
f regions2 : dust  atmospheric CO2

  • Marine biological effect: results of two different models and a hypothetical response

Bopp et al

Ridgwell


F 3 atmospheric co 2 temperature l.jpg
f regions3 : atmospheric CO2 temperature.

  • Use climate sensitivities for glacial – interglacial cycle from models, 2ºC antarctic temperature change for 200-280 ppm CO2 change.


Slide33 l.jpg

regions


Conclusions l.jpg
Conclusions regions

  • Simple marine biology sub-models for earth system models now exist.

  • First order effects on climate dynamics over periods > 102 years.

  • Magnitude of effects uncertain.

  • To do list:


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