Post on 28-Mar-2015
The carbon cycle and the Anthropocene
Michael Raupach1,2
1Centre for Atmospheric, Weather and Climate Research, CSIRO Marine and Atmospheric Research, Canberra, Australia
2ESSP Global Carbon Project
Thanks: Pep Canadell, Philippe Ciais, Ian Enting, John Finnigan, Pierre Friedlingstein, Corinne Le Quéré, David Newth, Glen Peters, Peter Rayner, Cathy Trudinger,
and many more GCP and CSIRO colleagues
"Earth System Science 2010: Global Change, Climate and People", 10-13 May 2010, Edinburgh, UK
Outline
The carbon cycle as a progenitor of the Anthropcene
The contemporary carbon cycle
• CO2 emissions trajectories
• Partitioning anthropogenic CO2 to air, land and ocean
Stabilising the carbon-climate-human system
• sharing a cumulative global quota on CO2 emissions
The carbon cycle as a progenitor of the Anthropocene
The biosphere
• A complex adaptive system based on carbon
• Evolving for 3.5 billion years
The anthroposphere
• One species finds a new evolutionary trick: use of exosomatic energy
• Easiest energy source: detrital carbon from the biosphere
• Evolving for tens of thousands of years
• Biologically based, with extra technological, social, cultural levels
A phase transition in human ecology
Since 1800, global per-capita wealth and resource use have doubled every 45 years
Growth rates (1860-2010)
• Population: 1.3 %/y
• GWP: 2.8 %/y
• GWP/Pop: 1.5 %/y
This exponential growth is the dominant instability in the earth system
Angus Maddison (http://www.ggdc.net/maddison/)
Global population and GDP
100
1000
10000
100000
0 500 1000 1500 2000
PopulationGDPpppPopulation (million)GWP (billion Y2000 $US / y)
Global per capita GDP
100
1000
10000
0 500 1000 1500 2000
doubling time = 45 y
GWP per capita(Y2000 $US / person / y)
AD 0 500 1000 1500 2000
Outline
The carbon cycle as a progenitor of the Anthropcene
The contemporary carbon cycle
• CO2 emissions trajectories
• Partitioning anthropogenic CO2 to air, land and ocean
Stabilising the carbon-climate-human system
• sharing a cumulative global quota on CO2 emissions
The carbon cycle since 1850
7.7
1.4
4.1
3.0 (5 models)
0.3 Residual
2.3 (4 models)
2000-2008(PgC y−1)
atmospheric CO2
ocean
land
fossil fuel emissions
deforestation
CO
2fl
ux
(P
gC
y−
1 )
8
6
4
2
0
−2
−4
−6
−8
1850 1900 1950 2000
other industrial emissions
tropicalnontropical
7.7
1.4
4.1
3.0 (5 models)
0.3 Residual
2.3 (4 models)
2000-2008(PgC y−1)
atmospheric CO2
ocean
land
fossil fuel emissions
deforestation
CO
2fl
ux
(P
gC
y−
1 )
8
6
4
2
0
−2
−4
−6
−8
1850 1900 1950 2000
other industrial emissions
tropicalnontropical
Le Quere et al. (2007) Nature Geoscience
0
5
10
15
20
25
30
1850 1900 1950 2000 2050 2100
Fo
ssil
Fu
el E
mis
sio
n (
GtC
/y)
CDIACIEAall
A1B(Av)A1FI(Av)A1T(Av)A2(Av)
B1(Av)B2(Av) Fossil fuels:
• 2007 emission 8.5 PgC
• 2008 emission 8.7 PgC
• 2000-08 growth: 3.4 % y1
Land use change:
• 2007 emission ~1.5 PgC
• 2000-07 growth: ~0 % y1
Without extra change in C intensity, GFC will "save" about 0.25 ppm CO2 increase
Global CO2 emissions
5
5.5
6
6.5
7
7.5
8
8.5
9
9.5
10
1990 1995 2000 2005 2010 2015
Fo
ssil
Fu
el E
mis
sio
n (
GtC
/y)
CDIACIEAallA1B(Av)A1FI(Av)A1T(Av)A2(Av)B1(Av)B2(Av)Projection
Graphs: Raupach et al. (2007) PNAS, with updated data: CDIAC to 2007, IEA to 2006
-4
-3
-2
-1
0
1
2
3
4
1990 2010 2030 2050 2070 2090
Gro
wth
rate
of f
ossi
l-fue
l CO
2 em
issi
on (%
/y)
A1B AIM (*)A1B ASFA1B IMAGEA1B MESSAGEA1B MINICAMA1B MARIAA1B SRES AverageA1FI AIMA1FI ASFA1FI IMAGEA1FI MESSAGEA1FI M INICAM (*)A1FI MARIAA1FI SRES AverageA1T AIMA1T ASFA1T IMAGEA1T MESSAGE (*)A1T MINICAMA1T MARIAA1T SRES AverageA2 AIMA2 ASF (*)A2 IMAGEA2 MESSAGEA2 MINICAMA2 MARIAA2 SRES AverageB1 AIMB1 ASFB1 IMAGE (*)B1 MESSAGEB1 MINICAMB1 MARIAB1 SRES AverageB2 AIMB2 ASFB2 IMAGEB2 MESSAGE (*)B2 MINICAMB2 MARIAB2 SRES Average1990-992000-052000-072000-10
a
bc
d
Observed growth ratesa: 1990-99b: 2000-05c: 2000-07d: 2000-10
-4
-3
-2
-1
0
1
2
3
4
1990 2010 2030 2050 2070 2090
Gro
wth
rate
of f
ossi
l-fue
l CO
2 em
issi
on (%
/y)
A1B AIM (*)A1B ASFA1B IMAGEA1B MESSAGEA1B MINICAMA1B MARIAA1B SRES AverageA1FI AIMA1FI ASFA1FI IMAGEA1FI MESSAGEA1FI M INICAM (*)A1FI MARIAA1FI SRES AverageA1T AIMA1T ASFA1T IMAGEA1T MESSAGE (*)A1T MINICAMA1T MARIAA1T SRES AverageA2 AIMA2 ASF (*)A2 IMAGEA2 MESSAGEA2 MINICAMA2 MARIAA2 SRES AverageB1 AIMB1 ASFB1 IMAGE (*)B1 MESSAGEB1 MINICAMB1 MARIAB1 SRES AverageB2 AIMB2 ASFB2 IMAGEB2 MESSAGE (*)B2 MINICAMB2 MARIAB2 SRES Average1990-992000-052000-072000-10
a
bc
d
Observed growth ratesa: 1990-99b: 2000-05c: 2000-07d: 2000-10
Raupach and Canadell (2010) COSUST
Emissions growth rates:SRES and observations
SRES scenariosdashed = marker
solid = family average
0
5
10
15
20
25
30
1850 1900 1950 2000 2050 2100
CDIACIEAall
A1B(Av)A1FI(Av)A1T(Av)A2(Av)
B1(Av)B2(Av)
Drivers of global emissions
Raupach et al. (2007) PNASUpdated with IEA data to 2006
World
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1980 1990 2000 2010
F (emissions)P (population)g = G/Ph = F/G
Kaya Identity
G
GP
FF
P
Fossil-fuel CO2 emission
Population
Per-capita GDP
Carbon intensity of GDP
Outline
The carbon cycle as a progenitor of the Anthropcene
The contemporary carbon cycle
• CO2 emissions trajectories
• Partitioning anthropogenic CO2 to air, land and ocean
Stabilising the carbon-climate-human system
• sharing a cumulative global quota on CO2 emissions
Cumulative CO2 emissionsas a measure of climate forcing
Allen et al. (2009, Nature)
Past FF reserves Unconventional
5301500-2000 >3000?
Pea
k w
arm
ing
fro
m p
rein
du
stri
al (
deg
C) A1FIA2
A1T
A1B
B2
B1
0 1000 2000 3000 4000 5000Q = cumulative CO2 emissions from preindustrial (PgC)
Trajectories of CO2 and T
Plot against time
Peaks in emissions, CO2 and temperature occur progressively later
CO
2 [p
pm
]Δ
T [
deg
K]
Time [years]
Total emissions quota Q(∞) [PgC]
1000
3000
1500
2000
2500
Emissions
CO2
Temperature
Trajectories of CO2 and T
Plot against Q(t)= cumulative emissions to time t)
Peak T is a nearly linear function of Q to time of peak
"Committed warming" becomes the warming between times of peak emissions and peak temperature
Cumulative emission Q(t) [PgC]
CO
2 [p
pm
]Δ
T [
deg
K]
Total emissions quota Q(∞) [PgC]
1000
3000
1500
2000
2500
1000
3000
1500
2000
2500
NOW
Cumulative emission targets and climate risk
Cumulative emissions (billion tonnes C)
Pea
k w
arm
ing
ab
ove
pre
ind
ust
rial
(oC
)
Probability of avoiding peak
warming
0.5
0.60.70.8
0.9
Past emissions Conventional fossil C reserves Unconventional reserves
After Allen et al. (2009, Nature)
The tragedy of the commons and beyond
Hardin (1968) - parable and lack of technical fix
Pretty (2003):
• social capital as a prerequisite for collective resource management
• 5 kinds of capital:natural, physical, financial, human, social
Dietz, Ostrom and Stern (2003):
• Adaptive governance in complex systems
• Emerges if there are ways to:• Provide information• Deal with conflict• Induce rule compliance• Provide infrastructure• Be ready for change
Hardin G (1968) The tragedy of the commons. Science 162, 1243.
Dietz T, Ostrom E, Stern PC (2003) The struggle to govern the commons. Science 302.
Pretty J (2003) Social capital and the collective mangement of resources. Science 302.
Reprinted in Kennedy D et al. (2006) Science Magazine's State of the Planet 2006-2007. Island Press, Washington DC.
√xxxx
Trajectories for capped CO2 emissions
Emissions trajectory is specified by long-term exponential decay at specified mitigation rate m
OR specified cap on all-time cumulative emissions Q∞:
There is a 1:1 mapping between m and Q∞
530 PgC to 2008 (FF+LUC)
Total emissions quota Q∞ [PgC]
1000
3000
Emission[PgC/y]
15002000
2500
LUC
FF
all
time
Q F t dt
m
Q∞
Summary
The carbon cycle as a progenitor of the Anthropcene
• A key enabler of the Anthropocene is the use of exosomatic energy
• The primary energy source was, and remains, detrital biotic carbon
The contemporary carbon cycle
• Fossil-fuel CO2 emissions have accelerated
• Partition fractions of anthropogenic CO2 to air, land and ocean have been nearly constant, because emissions have grown nearly exponentially and the C cycle has been nearly linear
• The total CO2 sink rate is decreasing, mainly through the ocean sink
Stabilising the carbon-climate-human system
• The task is to share a cumulative global quota on CO2 emissions
• Full equity (population sharing) is not possibleAttribution of historic emissions is not possible
• The most achievable sharing rule common to all major nations goes about 70% towards full equity