urbanisation and the global carbon cycle: links, …urbanisation and the global carbon cycle: links,...

Urbanisation and the global carbon cycle: links, drivers and implications

Michael Raupach, Pep Canadell and Shobhakar Dhakal

Global Carbon Project (IGBP-IHDP-WCRP-Diversitas)

International GCP workshop on Urbanization, development pathways and carbon implications, 28-30 march 2007, tsukuba, japan

Outline

u Carbon in the new planetary ecology

u Trends in CO2 emissions

• Recent acceleration

• Global and regional patterns and drivers

u Land and ocean CO2 sinks

• Future vulnerability

u Urbanisation

• Implications of the tragedy of the commons

Two nested ecologies

u Ecology of the biosphere

• Life is a complex adaptive system (CAS)

• Imports (solar) energy, exports entropy, stores information

• Evolves by sieving information (genome) about organisms (phenome)

• Genomes and phenomes are both carbon-based

u Ecology of the anthroposphere

• New evolutionary trick: use of exogenous (non-biotic) energy

• Easiest energy source: detrital carbon from the biosphere

• CAS with biological, technological, social, cultural levels

Carbon-climate-human system: forcing and response

Records (1850-2005) of:

u CO2 emissions from fossil fuels

u Changing CO2 concentrations in the atmosphere

u Changing global mean temperatures (from instrumental record with effects of urbanisation removed)

0

1

2

3

4

5

6

7

8

9

1850 1870 1890 1910 1930 1950 1970 1990 2010

Fo

ssil

Fu

el

Em

issio

n (

GtC

/y)

Emissions

280

300

320

340

360

380

400

1850 1870 1890 1910 1930 1950 1970 1990 2010

Atm

oap

heri

c [

CO

2]

(pp

mv) [CO2]

2 ppm/year

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1850 1870 1890 1910 1930 1950 1970 1990 2010

Tem

pera

ture

(d

eg

C)

Temperature 0.2 C/decade

FFemission to 2003 Marland, CDIAC

FFemission 2004-05 Marland PersComm

Global temperature Jones et al, CRU

CO2 1832-1958 LawDome 20yr

CO2 1959-now MaunaLoa

u For temperature and sea level, observed trends for 1990 to 2005 are at the upper edge of IPCC Third Assessment (2001) predictiions

Temperature

Sea level

Observed climate

response

Rahmsdorf, Church et al. (2007) Science

Canadell, Le Quere, Raupach et al. (2007)

PNAS (submitted)

Global budget of atmospheric CO2

Source from

land use change

Source from

fossil-fuel emissions

Ocean sink

Land sink

1960-2005:

45% of total emissions remain in

atmosphereAtmospheric accumulation =

FFoss + FLUC + FLandAir + FOceanAir

Outline







u Urbanisation


u Fossil-fuel CO2 emissions in 2005: 7.9 PgC

u Growth rate in fossil-fuel CO2 emissions (CDIAC):

• 1990 to 1999: ~1% per year

• 2000 to 2005: ~3% per year

Recent acceleration in CO2 emissions

Canadell et al. (2007) PNAS (submitted)Raupach et al. (2007) PNAS (submitted)

Compare:• actual emissions• emissions scenarios• stabilisation scenarios

u Scenarios underestimate actual emissions since 2000

u Emissions growth has increased from 1% pa in 1990s to over 3% pa since 2000

CO2 from fossil fuels:

global trends

Raupach et al. (2007) PNAS (submitted)

Graph to

appear i

n PNAS

CO2 from fossil fuels: regional trends


Graph to

appear i

n PNAS

Drivers of emissions:

population, energy, GDP

D3D2IndiaChinaFSUD1JapanEUUSA

u Key to regions

Primary energy use [EJ/y]

Population (millions)

GDP (market exchange rates)

Graph to

appear i

n PNAS

Formalism

u Basic variables (extensive: proportional to size of a homogeneous region)

• F = fossil-fuel CO2 emission

P = population

G = GDP

E = primary energy use

u Kaya identity (Nakicenovic 2004)

• F = P * (G/P) * (E/G) * (F/E)

= P * (G/P) * (F/G)

[Impact = Population * Affluence * Technology]

• or F = Pgef = Pgh

• where g = G/P = percapita GDP (Affluence)

e = E/G = energy intensity of GDP

f = F/E = carbon intensity of energy

h = F/G = carbon intensity of GDP (h = ef)

j = F/P = percapita FF emission (j = gh)

Drivers of global emissions

u Kaya Identity

G

GP

FF

P= × ×

Fossil-fuel CO2

emission

Population

Per-capita GDP

Carbon intensity of GDP

World

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1980 1985 1990 1995 2000 2005

F (emissions)

P (population)

g = G/P

h = F/G


Who contributes to fossil-fuel carbon?

u Depends on time scale (accumulation, current flux, current growth rate)


Graph to

appear i

n PNAS

Outline







u Urbanisation


Vulnerability of

carbon pools

u C4MIP = Coupled Climate Carbon Cycle Model Intercomparison Expt(Friedlingstein et al. 2006)

u Intercomparison of 11 coupled climate-carbon cycle models

u For all models, feedbacks =>• increased CO2

• more warming (by 0.1-1.5 deg)• higher AF (by 0.02-0.22)

u Main carbon-climate feedbacks:• ocean CO2 uptake• CO2 fertilisation of land NPP• climate effects on carbon

release from land pools

NOW

Processes influencing global land-air C fluxes

Drivers:

A: atmospheric

composition

B: physical

climate

C: land use

and land mgment

u In C4MIP

Process Driver Sign of land-to-air flux

(+,−) = (source, sink)

A1 CO2 fertilisation A −

A2 Nutrient constraints on CO2 fertilisation A +

A3 Fertilisation by nitrogen deposition A −

A4 Effects of pollution (eg acid rain, ozone, …) A +

B1 Response of respiration to warming and moisture B + (warming); ± (moisture)

B2 Response of NPP to warming and moisture B − (warming); ± (moisture)

B3 Radiation effects (eg direct/diffuse partition) B −

B4 Biome shifts B ±

B5 Permafrost thawing B +

B6 Changes in wildfire regime B + (rapid), − (slow)

B7 Changes in herbivore (eg insect) ecology B, C +

C1 Changes in managed fire regime C + (rapid), − (slow)

C2 Managed reforestation and afforestation C −

C3 Unmanaged forest regrowth (after cropland

abandonment)

C −

C4 Woody encroachment / woody thickening C −

C5 Deforestation and land clearing (eg forest to

savannah)

C +

C6 Peatland and wetland drainage C +

C7 Agricultural practices C ±

Vulnerability to release of frozen carbon

u CF0 = 900 PgC (from permafrost area and

permafrost soil C data)

u kFT = 0.001 [y-1 K-1] (Anisimov et al 1999:

warming of 2 degC over 100 y decreases

permafrost by 25%)

u Raupach, M.R. and Canadell, J.G. (2006).

Observing a vulnerable carbon cycle. In: Observing the Continental Scale

Greenhouse Gas Balance of Europe (eds.

H. Dolman, R. Valentini, A. Freibauer).

(Springer). (In press)

1750 1800 1850 1900 1950 2000 2050 2100

300

400

500

600

700

800

900

1000

CA

(pp

m)

1750 1800 1850 1900 1950 2000 2050 2100

300

400

500

600

700

800

900

1000

CA

(pp

m)

100 ppm

TA

(de

gC

)

1850 1900 1950 2000 2050 2100

0

1

2

3

4

5

TA

(de

gC

)

1850 1900 1950 2000 2050 2100

0

1

2

3

4

5

A1 without frozen-C feedback

A1 with frozen-C feedback

0.8 degC

u Response of CO2

u Response of temperature

Outline







u Urbanisation


Global trends in urbanisation 1950-2015

World

0

1000

2000

3000

4000

5000

6000

7000

8000

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015

Po

pu

lati

on

(m

illio

n)

Urban > 10M

Urban 5M to 10M

Urban 1M to 5M

Urban 0.5M to 1M

Urban < 0.5M

Rural

More Developed

0

500

1000

1500

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015Less Developed

0

1000

2000

3000

4000

5000

6000

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015Least Developed

0

500

1000

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015

UN Development Program data (August 2006)http://esa.un.org/unup/index.asp?panel=3

Populations of largest urban regions and cities

u 100 largest urban regions

1: Tokyo (35.2M)

100: Casablanca (3.1M)

--------------------------------

Total: 693M (10.7% of global)

u 60 largest cities1: Mumbai (12.78M)

60: Pune (3.06M)

-----------------------------

Total: 351M (5.4% of global)

u We are talking about urban

settlements of all sizes!

http://en.wikipedia.org/wiki/List_of_metropolitan_areas_by_populationAugust 2006

Populations of largest

urban regions and cities (2005)

0

2

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100

Rank

Po

pu

lati

on

(M

)

Urban RegionsCities

Tokyo region

(35M)

Affluence and consumption per unit area

u NASA Earthlights composite

Urban and rural

incomes: China

u Per capita income of urban and rural households in China, 1978 - 1997

u Heilig, G.K. (1999) Can China feed itself? A system for

evaluation of policy options. IIASA.

(http://www.iiasa.ac.at/Research/LUC/ChinaFood/index_h

.htm)

u Caption: This chart partly explains the attraction of cities

and towns for China's rural population. Whereas average

household income has risen significantly in rural areas, incomes in urban areas have increased even more. The

gap between urban and rural income has remained

almost unchanged.

u Source: China Statistical Yearbook, Beijing, 1998 (p.325)

u Note: Constant prices.

The tragedy of the commons

(Garrett Hardin, 1968)

u On a pasture open to all, each herdsman tries to maximise his gain by keeping as many cattle as possible on the commons.

u Eventually the commons become overgrazed.

u At that point, the utility to the herdsman of adding one more animal to his herd has a positive and a negative component:

• Positive component: nearly +1 animal

• Negative component: small fraction of -1, because all bear the cost of the incremental addition to overgrazing.

u So he adds one more animal. And so on, for each herdsman ...

u "Freedom in a commons brings ruin to all".

Hardin G (1968) The tragedy

of the commons. Science 162, 1243.

Reprinted in Kennedy D et al. (2006) Science Magazine's

State of the Planet 2006-2007.

Island Press, Washington DC.

The tragedy of the commons

(Garrett Hardin, 1968)

u "The essence of dramatic tragedy is not unhappiness. It resides in the solemnity of the remorseless working of things." (A.N. Whitehead, 1948, quoted by Hardin 1968)

u Hardin's examples:

• Exploitation of common resources (fish, forests, ...)

• Population

• Pollution

u Hardin's solution:

• Mutual coercion, mutually agreed upon by the majority of people affected

Hardin G (1968) The tragedy

of the commons. Science 162, 1243.

Reprinted in Kennedy D et al. (2006) Science Magazine's



Beyond the tragedy of the commons:

Two ways forward

u Critique by Dietz et al. (2003)

• State coercion and and private property are not the only institutions available to regulate commons

• Resource users are able to create solutions

u Adaptive governance in complex systems(Dietz et al. 2003)

• Emerges by evolution, if there are ways to:• Provide information• Deal with conflict• Induce rule compliance• Provide infrastructure• Be ready for change

u Social capital as a tool for collective resource management (Pretty 2003)

• natural, social, human, physical, financial capital

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



Climate change as a tragedy of the commons

u Danger is well known: emissions of CO2 and other greenhouse gases must be drastically reduced (by more than half) by 2050, to avoid dangerous climate change (> 2 degC global warming)(IPCC 2007; Hansen et al. 2007)

u "If Australia stopped all its greenhouse gas emissions, the benefit would be wiped out by growth of Chinese emissions in just 9 months" (Australian Prime Minister, J. W. Howard, 2006)

u This is true of everyone, including any Australia-size part of China!

u After over 15 years of climate change awareness, we have:

• No agreed global emissions caps

• No agreed global regulatory institution, either collaborative or coercive

u Exploitation of individual commons benefit (atmosphere as a free waste dump) continues unabated, despite years of awareness of common threat

Four response dimensions

u Technical

• Broad portfolio: renewables, cleaner FF, conservation ...

• A workable transition pathway that starts now

u Economic

• Market drivers: GH accounting, trading mechanisms

u Policy

• Emissions cap

• Price signals: policies to make greenhouse costs visible to the market

• Support for innovation (technical, economic, policy, socio-cultural)

• Removing perverse incentives

u Cultural and social: building social capital

• Global: protection of the commons as a global ethical imperative

• Local: decoupling quality of life from consumption

Conclusion: Three turning points

u The Crossroads of Gaia

• The Earth System is fragile

• Humans are now major participants

u The Crossroads of Kyoto

• Our first, flawed effort to build global social capital

u The Crossroads of Robert Johnson

• Unmaking the devil's bargain with our Gaian inheritance of detritalcarbon

World

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1980 1985 1990 1995 2000 2005

F (emissions)

P (population)

g = G/P

h = F/G

Hilary Talbot

urbanisation and the global carbon cycle: links, …urbanisation and the global carbon cycle: links,...

Documents