Where has all the Carbon Gone?

Atmospheric oxygen, carbon fluxes and the

implications for climate change.

Mark Battle (Bowdoin College)

Michael Bender (Princeton)Ralph Keeling (Scripps Institute of

Oceanography) Pieter Tans (NOAA/CMDL)

Jesse Bastide, Carrie Simonds, Blake Sturtevant, Becca Perry

Bates College, 12/3/2004

Funding from: NSF, EPA, NOAA GCRP, BP-Amoco, Bowdoin College

Organizing Principle:

1 topic superficially

Organizing Principle:

1 topic superficially

Several topics with vanishing content

Outline:

• Context:– Climate Change

– CO2 as an agent of change

• Where does the CO2 go?

• How does O2 tell us this?

• The basic answer• A more refined answer• Related work in progress

Why should we care about climate change?

“An increasing body of observations gives a collective picture of a warming world…”

“…most of the warming observed over the last 50 years is attributable to human activities.”

“ Anthropogenic climate change will persist for many centuries.”

“Emissions of greenhouse gases… continue to alter the atmosphere in ways that are expected to affect the climate.”

IPCC, 2001

Why CO2?

IPCC, 2001

Why CO2?

“ The atmospheric concentration of CO2 has increased by 31% since 1750. The present CO2 concentration has not been exceeded during the past 420,000 years and likely not during the past 20 million years. The current rate of increase is unprecedented during at least the past 20,000 years.”

IPCC, 2001

Where does anthropogenic CO2 end up?

Recap:

• The planet is warming• Human activities are to blame

• CO2 is the primary culprit

• Future buildup depends on Atm vs. Land vs. Ocean

• Land/Ocean partition is tough to measure

The link between O2 and CO2

CO2 = Land biota + Industry + Ocean O2 = Land biota + Industry

O2/N2 changes are small

O2/N2 per meg (O2/N2sa – O2/N2st)/(O2/N2st) x106

1 per meg = 0.0001%

1 GtC = 109 metric tons C = 1015 g C

1 GtC from FF 3.2 per meg O2/N2

Graphically…

Graphically…

Graphically…

Graphically…

Graphically…

The Princeton cooperative flask sampling network

Ships of opportunity

Research Vessels

Automatic Air Recovery Device Version ARK-5

In use at:

Cape GrimKa’imimoanaSamoaBarrowSableMacquariePrinceton

Our measurement technique:

• IRMS (Finnigan Delta+XL) 32/28 and 40/28 (as well as 44/28 and 29/28)

• Custom dual-inlet system• Indirect comparison with standards

For more details: Bender et al., In review

Battle et al., Science 2000

1991 – 1997Land sink = 1.4 ± 0.8 GtC/yr

Ocean sink = 2.0 ± 0.6 GtC/yr

Battle et al. Science 2000 (2467-2470)

Is it really that simple?

O2 = Land biota + Industry + OceanCO2 = Land biota + Industry + Ocean

Heat Biology

Longer records from more sites…

Longer records from more sites+

Solubility correction+

Stratification correction

Ocean uptake = 1.7 ± 0.5Net Land uptake = 1.0 ± 0.6

(1994 – 2002)

Bender et al. In review

Summary

• The climate is changing

• Anthropogenic CO2 is to blame

• O2 can tell us about the fate of CO2

• The O2-CO2 linkage isn’t trivial

• We find a substantial terrestrial sink (volatile?)

But the story doesn’t end here…

Measurements of O2 and CO2

O2 = Land biota + IndustryCO2 = Land biota + Industry +

Ocean

fland & focean > 0 for carbon storage by land and ocean

Measurements of O2 and CO2

O2 = Land biota + IndustryCO2 = Land biota + Industry +

Ocean

fland & focean > 0 for carbon storage by land and ocean

Determining the O2:CO2 stoichiometry for the

land biota

What else might we learn?

O2 = Land biota + IndustryCO2 = Land biota + Industry +

Ocean

fland & focean > 0 for carbon storage by land and ocean

APO: an ocean-only “tracer”

APO O2observed + 1.1 CO2observed

(I have ignored units)

APO: an ocean-only “tracer”

APO O2observed + 1.1 CO2observed

(I have ignored units)

So what?

Ocean biology and circulation

Ocean biology and circulation

fluxes of CO2 and O2

Ocean biology and circulation

fluxes of CO2 and O2

atmospheric transport

Ocean biology and circulation

fluxes of CO2 and O2

atmospheric transport

atmospheric compositionat observing stations

fluxes of CO2 and O2

atmospheric transport

atmospheric compositionat observing stations

APO measurements + good flux estimates

rigorous test of atmospheric transport

Is this different from other models?