Earth2Class Workshops for Teachers
State of Carbon Cycle in 2009 in the Eve of
the Copenhagen International Climate Conference:
Challenge to the Humanity
Taro Takahashi
Lamont-Doherty Earth Observatory of
Columbia University
November 21, 2009
Air CO2 at Mauna Loa and South Pole, 1957-2000
Global Carbon Cycle
Fossil Fuel Emissions: Actual vs. IPCC Scenarios
Global Fossil Fuel Emissions
10
International Energy Agency
-1
Fossil Fuel Emission (GtC y )
Carbon Dioxide Information Analysis Center
9
Projection
A1B
8
A1FI
Projection 2009
Emissions: -2.8%
GDP:
-1.1%
C intensity: -1.7%
A1T
A2
7
6
5
1990
B1
B2
3.4% per year
1 % per year
1995
2000
2005
2010
Raupach et al. 2007, PNAS, updated; Le Quéré et al. 2009, Nature-geoscience; International Monetary Fund 2009
2015
CO2 emissions (PgC y-1)
Annual Emission Rate of Carbon to the Atmosphere
5
55%
Annex B (Kyoto Protocol)
4
Developed Nation
3
45%
Developing Nations
2
Non-Annex B
1990
2000
Le Quéré et al. 2009, Nature-geoscience; CDIAC 2009
2010
Fossil Fuel Emissions: Top Emitters (>4% of Total)
Top Emitters (Countries) of Fossil Fuel Emissions
Carbon (tons x 1000)
2000
1600
USA
1200
China
800
Russian Fed.
400
Japan
India
0
1990 03
95
07
99
01
Time
Global Carbon Project 2009; Data: Gregg Marland, CDIAC 2009
03
05 2007
Components of FF Emissions
CO2 emissions (PgC y-1)
Components of Fossil Fuel Emissions
4
40%
Oil
3
36%
Coal
2
Gas
1
Cement
0
1990
2000
Le Quéré et al. 2009, Nature-geoscience
2010
Per Capita CO2 Emissions
Develop
countries
continue to
lead with the
highest
emission per
capita
1.3
(tC person-1 y-1)
Per Capita Emissions
Per Capita CO2 Emissions (World Mean)
1.2
1.1
1990
1995
2000
Le Quéré et al. 2009, Nature-geoscience; CDIAC 2009
2005
2010
Total Anthropogenic Carbon Emissions
CO2 emissions (PgC y-1)
Total Anthropogenic Carbon Emissions
10
8.7
8
Fossil fuel
6
9.9 PgC
4
Land use change
2
1960
1970
1980
1990
1.2
2000
Le Quéré et al. 2009, Nature-geoscience; Data: CDIAC, FAO, Woods Hole Research Center 2009
2010
12% of total
anthropogenic
emissions
Modeled Carbon Sink Rates for Land Biosphere and Oceans
Le Quéré et al. 2009, Nature-geoscience
Carbon Accumulation Rates in the Atmosphere
Evolution of the fraction of total emissions that remain in the atmosphere
CO2 Partitioning (PgC y-1)
Accumulation rates of CO2 in air
10
Total
CO2 emissions
8
(Estimated)
6
Atmosphere
4
(Measured)
2
1960
1970
1980
1990
Data: NOAA, CDIAC; Le Quéré et al. 2009, Nature-geoscience
2000
2010
CO2 EMISSIONS, SEA AND
LAND UPTAKE
1970
1980
1990
2000
All units are in Pg-C per year
(1 Peta-gram = 1015 grams
= 1 Giga tons)
Balance in recent years:
Industrial emissions ~ 8.5 Pg-C/yr
Land use change
~ 1.5 Pg-C/yr
TOTAL EMISSIONS ~ 10.0 Pg-C/yr
1970
1980
1990
2000
Atmospheric growth 4.5 Pg-C/yr
Land biota uptake
~ 4 Pg-C/yr
Ocean uptake
~ 2 Pg-C/yr
RESERVOIRS
~10.5 Pg-C/yr
RESIDUALS = (TOTAL EMISSIONS)
-(ATM.) – (LAND) – (OCEAN)
= ~ 0 on the average, but vary from
+3 to –3 Pg-C/yr from year to year.
Le Quere et al. (2009) Nature GS.
Airborne Fraction of Anthropogenic Carbon Emissions
Fraction of total CO2 emissions that remains in the atmosphere
(Amount of Carbon Increase each year)/(Annual Total Anthropogenic Emission)
1.0
Airborne Fraction
Trend: 0.27±0.2 % y-1 (p=0.9)
0.8
45%
40%
0.6
0.4
0.2
1960
1970
1980
1990
2000
2010
Are the natural carbon sinks weakening?
Le Quéré et al. 2009, Nature-geoscience; Canadell et al. 2007, PNAS; Raupach et al. 2008, Biogeosciences
Sea-Air CO2 Exchange and CO2 partial pressure
CO2 in seawater = {[CO2]aq + [H2CO3]}+[HCO3-] +[CO3=]
0.5 – 1 %
97%
2.5%
Sea exchanges CO2 molecules with air only through
[CO2]aq. Since [CO2]aq cannot be distinguished from [H2CO3],
they are commonly considered together.
Partial pressure of CO2 (pCO2) in seawater is a measure
of the exchangeable CO2 molecules, and may be considered as
“vapor” pressure of CO2.
When pCO2 in seawater is greater than that in the overlying
air, CO2 escapes from seawater to air. When pCO2 in
seawater is smaller than that in the overlying air, CO2 in air is
absorbed by seawater. pCO2 in seawater is sensitively affected
by temperature, photosynthesis and calcification.
Long-term Changes
BERMUDA TIME SERIES (N. R. BATES, JGR, 2007)
1984-2004 MEAN RATE = 1.80±0.013 matm/yr for ocean, 1.80 matm/yr for air
1989-2007 HAWAII TIME SERIES (HOT), Dore et al. PNAS, 2009
Air pCO2 change rate
= 1.68 ± 0.03 matm/yr
Ocean pCO2 change rate
= 1.88 ± 0.16 matm/yr
Ocean pH change rate
= -0.0019 ± 0.0002 /yr
DISTRIBUTION OF SURFACE WATER PCO2, TEMPERATURE AND SALINITY
IN THE U.S. WEST COAST, JUNE-AUGUST, 2002; AND 1997-2005 TIME SERIES
OF SURFACE WATER PCO2 IN THE MONTREY BAY (F. CHAVEZ, MBARI)
Observed Rate of Change in the Sea-Air pCO2 Difference
Zero = Ocean pCO2 increase rate is same as the atmospheric pCO2
Red = Ocean pCO2 increase rate is faster than the atmospheric pCO2
Blue = Ocean pCO2 increase rate is slower than the atmospheric pCO2
1981-2007
matm per year
Ocean
outgas
uptake
Le Quéré et al. 2009, Nature-geoscience
CHANGE IN WINTER TIME SURFACE WATER pCO2
IN THE ICE-FREE ZONE (POOZ) OF THE SOUTHERN OCEAN
1.50°C < SST < 2.50°C; Day of year, 172 to 326 (late June – mid-Nov)
pCO2
@ SST
(uatm)
Year
SUMMARY AND CONCLUSIONS
1) The anthropogenic emissions of CO2 are rapidly increasing at the
fastest rate anticipated by IPCC (3.4% per year) as a result of
increases in “per capita carbon production rates” and human
population. 2008 is an exception due to the economic recession.
2) While the carbon emissions from the Developed Countries
increased only modestly, those from Developing Countries
(China and India) increased very rapidly. The Developing
Countries exported manufactured goods as they increased
“Carbon emissions”.
3) The carbon cycle in the modern world is broadly understood in
the decadal scale, but not in the annual scale satisfactorily.
4) The ocean CO2 sinks may be weakening for the past decades,
while the land biota sink appears to be holding steady.
5) Unless the CO2 emissions are reduced substantially, the
atmospheric CO2 concentrations would double the pre-industrial
level by 2030. The presumed “tipping point” for the global
warming of 4°F may be exceeded then.
CLIMATOLOGICAL MEAN SEA-AIR pCO2 DIFFERENCES
FEBRUARY,
2000
AUGUST,
2000
Mean Annual Rate of Net Sea-Air CO2 Flux
Takahashi et al. (Deep Sea Res., 2009)
ATMOSPHERIC CO2 – MARINE PHOTOSYNTHESIS - CALCIFIERS
CaCO3 + CO2 + H2O
SHELLS
FORAMINIFERA
COCCOLITHS
CORALS
AIR/SEA
OCEAN
= Ca++ + 2 HCO3DISSOLVED
Increase in atmospheric CO2 causes dissolution of CaCO3.
(The reaction goes to right)
Increase in the photosynthetic utilization of CO2 encourages
The growth of CaCO3. (The reaction goes to left.)
Precipitation of CaCO3 causes seawater to lose CO2 to air.
(The reaction goes to left.)
pCO2 and Coral Growth Rate
Volume of Liquid CO2 Emissions and Sequestration Capacity
Global CO2 Emissions
~ 6 Gigatons-C/yr
(1 Gigaton = 1 billion tons = 1015 grams)
Volume as liquid CO2 ~ 30 ft x 50 miles x 50 miles
U. S. Emissions
~1.3 Gigatons-C/yr
Volume as liquid CO2 ~ 30 ft x 10 miles x 10 miles
(3600 x Giant Stadium)
-----------------------------------------------------------------Depleted gas reservoirs
0.5 – 170 Gigaton-C
“Depleted” oil reservoirs
3 – 80 Gigatons-C
Land aquifers
50 – 14,000 Gigatons-C
Juan de Fuca Ridge
Deep ocean rocks
250 Gigaton-C
Very large ?
Growth Rate of Emissions from Coal Burning, 2006 to 2008
2006-2008
CO2 emissions (TgC y-1)
300
250
90% of growth
200
150
100
50
0
China
India
US
-50
CDIAC 2009; Global Carbon Project 2009
World
Net CO2 Emissions from LUC in Tropical Countries
Net C Emissions from Land Utility Changes in Tropical Countries
2000-2005
CO2 emissions (TgC y-1)
600
500
400
60%
Brazil
Indonesia
300
200
Cameroon
Venezuela
Peru
Rep.Dem.Congo
100
Colombia
Nicaragua
India
Nigeria
Philippines
Nepal
0
4-2%
2-1%
RA Houghton 2009, unpublished; Based on FAO land use change statistics
<1%
Summary of Carbon Budget, 2000-2008
2000-2008
PgC
Source
7.7
Exo-tropics
Tropics
deforestation
atmospheric CO2
Sink
CO2 flux (PgC y-1)
fossil fuel emissions
land
ocean
Time (y)
Global Carbon Project 2009; Le Quéré et al. 2009, Nature-geoscience
1.4
4.1
3.0 (5 models)
2.3 (4 models)
0.3 Residual