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Atmospheric Carbon Dioxide Observations and Climate
Change on Local to Global Scales
Britton Stephens
National Institute for Water and Atmospheric
Research, Wellington
Baring Head – Southerly Interval CO2 Record
Baring Head – Southerly Interval CO2 Record
Oceans and land plants have provided a
50% climate discount, but future is unclear
Outline:
1. Global climate change
current observations and future
risks
2. Carbon cycle observations
emission verification and process
understanding
3. Baring Head CO2 record
Southern Ocean carbon fluxes
4. HIPPO Global aircraft campaigns
Continental carbon fluxes
H2O
CO2
CH4
N2O
O3
CFCs
Without atmospheric greenhouse gases, the average
temperature of Earth would be -18 °C or 0 °F
The Global Carbon Cycle
The global carbon cycle for the 1990s, showing the main
annual fluxes in GtC yr –1. [IPCC, 2007]
How warm is it going to get?
Uncertainty due to
climate models
}
Uncertainty due to
trees and oceans
[IPCC, 2007]
Uncertainty
due to people
Stabilization Targets for Atmospheric
Greenhouse Gas Concentrations
U.S. National Research Council, 2010
Changes in the mean lead to changes in the extremes
Stabilization Targets for Atmospheric
Greenhouse Gas Concentrations
U.S. National Research Council, 2010
Observed changes: Global air temperatures
[IPCC, 2007 and
references therein]
Observed changes: New Zealand air temperatures
[http://www.niwa.co.nz
]
Observed changes: Spring snow
[IPCC, 2007 and references therein]
Observed changes: Arctic Sea-Ice
Arctic Sea Ice in September
[IPCC, 2007 and references therein]
[Stroeve, et al., GRL, 2007; NSIDC, 2008]
Observed changes: Sea-level
[US NRC, 2010]
Observed changes: Ocean Heat Content
[IPCC, 2007 and references therein]
[Murphy et al., JGR 2009]
Observed changes: Glacier Retreat
Glacier Bay, Alaska
1941
1988
[US NRC, 2010]
Photos: USGS
http://www.grid.unep.ch/glaciers/
Observed changes: Ice-sheet Mass
[Velicogna, GRL 2009]
Observed changes: Polar bear weights
[Stirling and Parkinson, Arctic, 2006]
Observed changes: Lizard Extinctions
Science 328, 894 (2010);
Barry Sinervo, et al.
Erosion of Lizard Diversity by
Climate Change and Altered
Thermal Niches
Observed changes: Spring bloom
[Amano, Proc. Roy. Soc., 2010]
Which of these will have the biggest impact, or will it
be a surprise?
[Nicholis and Cazenave, Science 2010]
What does 1 m sea-level rise look like?
What does 1 m sea-level rise look like?
[Wellington City Council, 2009]
Effects on New Zealand may have more to do with
events elsewhere
At risk coastal areas have: dense populations,
low elevations, appreciable rates of subsidence,
and/or inadequate adaptive capacity.
Stabilization Targets for Atmospheric
Greenhouse Gas Concentrations
U.S. National Research Council, 2010
Effects on New Zealand may have more to do with
events elsewhere
Summary 1: What should we do?
• Major decisions involve complex social,
economic, and political factors
• Nonetheless, many options/needs are
quite clear
• Conservation and energy efficiency
• Renewable energy sources
• CO2 capture and storage
• Education
• Prepare to adapt to climate changes
The scale of the challenge is enormous
Existing global infrastructure
As a visual aid, dry ice is
CO2 in solid form
One 40 liter tank of gas
produces 95 kg of CO2
Required emissions cuts well beyond current agreements
Our ability to verify emissions is inadequate to support
international treaties
National Emission Estimate Uncertainties
Source or Sink
Method
Present
5 Year Potential
Fossil‐Fuel Combustion
UNFCCC
< 10 to 25 %
< 10%
Atmospheric Obs. and Models
UNFCCC
50 to > 100 %
< 10 to 50 %
< 10 to 100 %
< 10 to 50 %
> 100 %
50 to > 100 %
10 to 100 %
10 ‐ 50 %
Agriculture, Forestry, Land‐use
Atmospheric Obs. and Models
Satellite Obs. and Models
Verifying Greenhouse Gas Emissions: Methods
to Support International Climate Agreements
U.S. National Research Council, 2010
Our understanding of processes is inadequate to support
prediction
[IPCC, 2007]
How well can we predict carbon-cycle feedbacks?
(PgCyr-1)
(PgCyr-1)
C4MIP Projections
[Friedlingstein, et al., J. Climate, 2006]
In 2050, combined offsets have a range of 2.5 to 15 PgC/yr
At $32/ton CO2, ± 6 PgC/yr = ± $700 Billion/yr
The Southern Ocean will play a key role in future
anthropogenic CO2 uptake, mediated by opposing
influences
[Gruber et al., GBC 2009]
Direction and magnitude of response to
increased circumpolar winds is uncertain
ORCA-PISCES-T
sea to air = positive
UVic-ESCM
[Zickfeld et al., Science 2008]
[Le Quéré et al., Science 2007]
Surface CO2 observations and knowledge of wind
patterns can be used to make flux estimates
Wealth of information in short-term variability
Baring Head CO2 from August 2002
5-minute
observations
Steady
Southerly
Interval
Steady intervals capture air from high-latitude Southern Ocean
Updated automated data-processing system
Summary 2
• Baring Head provides a valuable and
unique record of CO2 changes in the
Southern Hemisphere
• Recent changes with respect to MLO
and SPO are larger than expected
• Atmospheric transport, local
ocean fluxes, or unknown causes
• Possibly still driving inverse result
• Data during Northerlies may be
useful for verifying New Zealand
emissions
Inverse models disagree by billions of tons C
Dominant source of model error is vertical mixing
[figure courtesy of Scott Denning]
Observations are made primarily at the surface and by flasks
• PIs: Harvard, NCAR, Scripps, NOAA, others
• Global and seasonal survey of CO2, O2, CH4, CO,
N2O, H2, SF6, COS, CFCs, HCFCs, O3, H2O, CO2
isotopes, Ar, black carbon, and hydrocarbons
• NSF / NCAR Gulfstream V
• 5 campaigns over 4 years
• Continuous profiling from surface to 10 km, and to
15 km twice per flight
• hippo.ucar.edu (also Facebook, Twitter, YouTube)
Canterbury, New Zealand
Pago Pago, American Samoa
Brooks Range, Alaska
NSF/NCAR Gulfstream V Jet (GV)
(HIAPER = High-performance Instrumented
Airborne Platform for Environmental Research)
Aircraft Performance
Maximum Range¹
Maximum Cruise Altitude
Maximum Payload
6,500 nm
51,000 ft
6,500 lb
12,046 km
15,545 m
2,948 kg
HIPPO1 CO2 Slices, 2009
Early January
(southbound)
Late January (northbound)
HIPPO2 CO2 Slices, 2009
Early November
(southbound)
Late November
(northbound)
HIPPO3 CO2 Slices, 2010
Late March (southbound)
Early April (northbound)
NH Fall to Spring Build-up
Preliminary CO2 model comparisons for HIPPO1
Observed
ACTM
GEOS-CHEM
CarbonTracker – Jan. Mean
NZ
Other species provide key complementary information
O2
CH4
CO
SF6
Other species provide key complementary information
H2O
N2O
O3
Black Carbon
Summary 3
• HIPPO campaigns are defining large-scale
gradients in CO2 and other species, and
their progression through the seasons with
unprecedented resolution
• These observations have the potential to
resolve on the order of 5 billion of tons of
carbon flux uncertainty (20 billion tons CO2)
Looking ahead:
• Climate change is real, and
poses significant risks to
natural, economic, and
political systems
• Improved observations of
atmospheric CO2 and
improved models of
atmospheric transport are
necessary for prediction
and verification
• Baring Head measurements and analyses promise
valuable insights
• Additional New Zealand observing site(s) planned
• Two more HIPPO campaigns will complete seasonal
picture
Wind direction and strength determines variability
Lauder in-situ CO2
Measurements
BHD – LDR up
to 5 ppm during
peak growth [will
be presented by
V. Sherlock]
Where to site a third (or
fourth CO2 instrument?
Required
• Line power
• Shelter
• Tower above local sources
Highly desirable
• Internet access
• Local scientific staff
• Regular visits by NIWA
field team
• Ancillary meteorological or
ecosystem observations