Download Bates_2004 - Bowdoin College

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 Grim
Ka’imimoana
Samoa
Barrow
Sable
Macquarie
Princeton
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 – 1997
Land 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?
Heat
Biology
O2 = Land biota + Industry + Ocean
CO2 = Land biota + Industry + Ocean
Longer records from more sites…
Longer records from more sites
+
Solubility correction
+
Stratification correction

Ocean uptake = 1.7 ± 0.5
Net 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 + Industry
CO2 = Land biota + Industry + Ocean
fland & focean > 0 for carbon storage by land and ocean
Measurements of O2 and CO2
O2 = Land biota + Industry
CO2 = 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 + Industry
CO2 = 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 composition
at observing stations
fluxes of CO2 and O2
atmospheric transport
atmospheric composition
at observing stations
APO measurements + good flux estimates

rigorous test of atmospheric transport
Is this different from other models?