Coastal CO2 fluxes: A survey, syntheses, and issues...

Coastal CO2 fluxes: A survey, syntheses, feedbacks and issues

Joe Salisbury et al., University of New Hampshire

Unsuspecting participants:

Nick Hardman‐Mountford (PML)Emmer Litt (PML)Wei‐Jun Cai (UGA)Alberto Borges (FRS‐FNRS)Goulven G. Laruelle, (Utrecht)C‐T Arthur Chen (Sun Yat Sen U.)L.‐S. Schiettecatte (Liege)N. Gypens (U. Bruxelles)E. Shadwick (Dalhousie)H. Thomas (Dalhousie)Doug Vandemark (UNH)Chris Hunt (UNH)Mike Degrandpre (U. Mont)Brent G.T. Else (U. Manitoba)Nick Bates (Bermuda Bio Lab)

G.E. Friederich (MBARI)Francisco Chavez (MBARI)Burke Hales (OSU)Wiley Evans (OSU)C. Goyet (WHOI)Ajit Subramaniam (LDEO)Taro Takahashi (LDEO)Wade McGillis (LDEO)Rik Wanninkoff (AMOL)J.F. Ternon (IRD)A Kortzinger (Keil)S. Cooley (WHOI)S. Lohrenz (UMASS)X Gao (Xiamen University)M. Previdi (LDEO)D. Turk (Dalhousie)

In a nutshell (Cai, 2011)

∴ Net coastal a‐s flux ~0 molC m‐2 y‐1

A limited survey of CO2 fluxes in coastal regions 

(I try to use molC m‐2 y‐1)

Site Survey: Estuaries~+30 molC m-2 y-1 (Chen and Borges, 2009)

n = 51

But note….

If we include proximal above ground biomass,

…then the sum of (aquatic + above ground) << 0 molC m2 y-1

Site survey: Temperate marginal seas(just a few examples)

Syntheses ‐ they are a sink e.g.‐ Cai, 2006: ‐1.9 molC m‐2 y‐1

‐ Borges, 2005:  ‐0.73 molC m‐2 y‐1  

(included estuaries)

‐ Laurelle, 2010: ‐0.80 molC m‐2 y‐1

Liverpool Bay pCO2 (Litt, Hardman – Mountford et al)annual flux = ‐4.0 mol m‐2 y‐1

North SeaThomas et al., 2005

Annual flux (molC m‐2 y‐1)North  ‐1.64South  0.22Total   ‐1.32

Scotian Shelf Canada:  Shadwick et al., 2010Annual flux (molC m‐2 y‐1) =  +1.4

Air‐sea flux dpCO2 controls

Gulf of MaineVandemark et al., 2011

Annual fluxes (molC m‐2 y‐1)= +0.38 (a weak source)

winter    0.2spring     ‐3.0summer 0.5

` fall 3.6

Degrandpre et al., 2002Mid  Atlantic Bight

Annual flux (molC m‐2 y‐1)~‐1.0

South Atlantic BightJaing et al., 2009

Annual flux (molC m‐2 y‐1)= 0.48 ± 0.21

Same shape as MAB, but much warmer

Site SurveyCoastal Polar Seas: A sink with changes on the horizon

Annual flux ‐5.4 to +3.2 mol m‐2 y‐1

It’s cold

It’s seasonally productive But Arctic receives ~10% of land flux

Bates et al., 2007Chuckchi Sea

Annual flux-1.88 molC m-2 y-1

Shadwick et al., 2011Beaufort Sea

Annual flux-1.2 molC m-2 y-1

Else et al., 2008Hudson Bay (-0.2 molC m-2 d-1)Measured daily fluxes less “sinky” likely terrestrial and FW influence

Antarctic Shelves (only one study?)

Carillo and Karl., 1999-2.2 molC m-2 d-1, for Summer only

Coastal upwelling regions Consensus is that the intergral = CO2 source

Cai, 2006: 0.70 molC m‐2 y‐1

Borges, 2005:  1.09 molC m‐2 y‐1

Laurelle, 2010: 0.91 molC m‐2 y‐1

Denitrification matters regionally!

Variability in  pCO2 offshore from Monterey CA USA (Chavez and Friedrich)

Distance offshore (km)

Air sea flux (molC m‐2 y-1) from (Friedrichs et al., 2002)

-0.5 during El Niño+1.9 during La Niña

Variability in Coastal Upwelling (California coast) 

Friedrich et al., 2008Peruvian upwelling

Annual flux+5.7 molC m‐2 y-1

Sea-Air CO2 fluxes from ICON (D338, 2009) in the Mauritanian Upwelling• Lagrangian tracking of filaments using SF6 and surface drifters

-1

-0.5

0

0.5

1

1.5

2

2.5

12/04 17/04 22/04 27/04 02/05 07/05 12/05 17/05 22/05 27/05

mm

ol C

O2

m-2

h-1

Lagrangian filament 1 = 3.65 mol CO2 m-2 y-1

Lagrangian filament 2 = 6.03 mol CO2 m-2 y-1

-1

-0.5

0

0.5

1

1.5

2

2.5

12/04 17/04 22/04 27/04 02/05 07/05 12/05 17/05 22/05 27/05

mm

ol C

O2

m-2

h-1

Lagrangian filament 1 = 3.65 mol CO2 m-2 y-1

Lagrangian filament 2 = 6.03 mol CO2 m-2 y-1

Hardman-Mountford et al., in prep. (2011)

Borges and Frankignoulle, 2003 Galacian upwellingAnnual flux -3.5 to -7.0 molC m‐2 y-1

But coastal upwelling regions can be sinks too!

Hales et al., 2007Oregon coastal upwelling region

Annual flux-7.3 molC m‐2 y-1 !!

Evans et al., 2011 Oregon coastal upwelling:Still a sink but now only −0.3 mol m−2 yr−1

Hales et al., missed some of this

Air sea exchange in plumes:

‐ Connectivity to the land can extend way beyond the shelf

‐Big terrestrial fluxes including buoyancy and heat

‐Variable DIC and buffering

Subramanium et al., 2008

Takahashi et al., 1993

dpCO2 < -150, measured by a very young R. Wanninkoff

Kortzinger et al, 2003

Sub atmospheric pCO2 (right)“Sink” Map (below)

From Cooley et al., 2007

The plume is a sink over the whole year-0.9 molC m‐2 y-1

In the Gulf of Mexico Lohrenz et al, 2010Mississippi plume (mmolC m‐2 d-1):

April and Oct -2.96 to -1.38August +4.20 to +5.31

Gao et al, 2007Yangzte estuary -plume

6.9 molC m‐2 y-1

But note the activity at the distal edge(250 uatm)!!

Synthesis of  all coastal systems Author Flux molC m‐2 y‐1 Flux Pg y‐1

Tsungoni et al., 1999 ‐3.33 ‐1.00

Thomas et al., 2004 ‐1.33 ‐0.40

Borges, 2005 ‐1.23 ‐0.37

Borges et al., 2005 ‐1.50 ‐0.45

Cai et al., 2006 ‐0.73 ‐0.22

Chen and Borges, 2009 ‐1.13 ‐0.34

Cai., 2011 ‐0.79 ‐0.21

Laurelle et al, 2011 ‐0.70 ‐0.24

Converging ?

Converging at ~0.25 Pg y-1?

Carbon cycling and air sea carbon exchange in coastal waters:

Feedbacks and Issues

Borges et al., 2011 Feedbacks affecting net CO2 uptake in coastal regions

1) Changes in coastal physics2) Changes from the land (constituent fluxes and hydrology)3) Changes to carbonate chemistry

Take home message is that the coastal regions may get sinkier:

N flux from land >>  (benthic calcification + dissolution)

ALSO – we need better models to evaluate feedback scenarios.

Issues:

Sampling issues

time/ space / depth

Sampling issues:  depth of ship’s intake can miss a rain lenses, a thin plume, or a hot surface layer 

Turk et al., 2010

Temporal sampling: A stormy period tweaks the annual budget!

Gulf of Maine (2007), ~20% of annual source term in ~3 weeks

Issues -We’re still learning: Recent Revisions/ Questions

Gulf of Maine: - 0.20 (Salisbury et al, 2009)+0.38 (Vandemark et al., 2011)

South Atlantic Bight +2.50 (Cai et al., 2003)+0.48 (Jaing et al., 2009)

Northwest Upwelling -7.30 (Hales et al, 2007)-0.30 (Evans et al., 2011)

Yangtze Plume +6.9 (Gao et al. 2007)??? (include distal plume)

Estuaries versus estuary-plume systems versus marsh-estuary-plume systems

Salinity

Issue: Are we counting plumes correctly????

Left: Salisbury et al., 2011Below Right: NASA SeaWiFSBelow left: KORDI GOCI

Plume Issue: Vigorous autotrophic uptake in plumes, but where are the nutrient vectors?

Issue:  Know thy land fluxes (carbonate system, nutrients, buoyancy, light attenuation, heat)

Spatially variable and….they are changing!

e.g. Omega from Salisbury et al., 2008

Issue: Understanding that ubiquitous pCO2depression under low nutrient conditions 

a) Carbon over consumption

a) Variable seasonal buffering

b) The effects of precipitation

Cai et al., 2010, Science

ISSUES: The Arctic‐ Impact of Changing Ice Cover (may not be a big sink as thought)

A (atmospheric invasion) B (Biological uptake) C (Cooling)R (River Input) I (Ice melt) W (warming)

Conclusions:

1.We’re converging on global numbers (0.2 –0.4 Pg y-1), but internal consistency of sampling and definition of the coast still needs work.

2.Likely non linear changes in store as dTerrestrial fluxes and dClimate conspire.

3.Time series are still needed: Everywhere, but especially where climate and fluxes are changing rapidly.

Thanks!

Extra slides

Plume Issue: Vigorous autotrophic uptake, but where are the nutrient vectors?

Possibilities

1.Nitrogen fixation (Subramanium et al., 2008)

2.Remineralization of DON (Morrell and Corredor, 2001)

3.Eddy pumping (Longhurst, 1995)

Potential Feedbacks (Borges, 2011)

Take home message is that the coastal regions may get sinkier:

N flux from land >>  (benthic calcification + dissolution)

ALSO – we need better models to evaluate feedback scenarios.

Goyet et al., 1995Arabian Peninsula upwelling region

Annual flux+0.46 molC m2 y-1

In a nutshell redux: Laurelle et al., 2010Net coastal a‐s flux ‐0.7 molC m2 y‐1

Potential Feedbacks (Borges, 2011)

Gao et al, 2009Pearl River Estuary-Plume6.9 molC m2 y-1

Salisbury et al., (submitted)   Controls on dpCO2 (big signals, but little net flux)

Coastal CO2 fluxes: A survey, syntheses, issues

1. An cursory survey of CO2 flux work in coastal waters

2. Syntheses

3. Potential future feedbacks and Issues

Ternon et al, 2000

The Amazon Plume is a Sink!

Issue:Where is the coast? What do we include in our analyses?Examples:

1.Marsh : Estuary : Plume =Autotrophic: Heterotrophic: Autotrophic

2. The Amazon Plume can have 2x106 km2

over the shelf. That’s > 7% of the coastal surface area.

Southern North Sea: Gypens et al, 2011

Annual flux (molC m2 y‐1)range:‐ 0.8 Seine plume+1.8 Thames plume

AlsoSchiettecatte et al., 2007 −0.65

Laurelle et al., 2010 (Small area, but big, positive fluxes)

Site Surveys: Estuaries

From +17.3 to +28.5 molC m2 y-1

Cooley et al, 2007

If I did the math correctly this is averages to -0.9 molC m2 y-1

Simulation of Low and High NAO: Previdi et al., 2009 East coast, USA

Differences attributable to: North (SST and NEP)South (Wind speed)

Low NAO (1985)(much sinkier!!)

Why?GOM (SST and NEP)MAB (Wind speed)

High NAO (1990)