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
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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
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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 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
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
Raupach et al. (2007) PNAS (submitted)
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
Raupach et al. (2007) PNAS (submitted)
Who contributes to fossil-fuel carbon?
u Depends on time scale (accumulation, current flux, current growth rate)
Raupach et al. (2007) PNAS (submitted)
Graph to
appear i
n PNAS
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
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
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
State of the Planet 2006-2007.
Island Press, Washington DC.
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
State of the Planet 2006-2007.
Island Press, Washington DC.
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