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