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

Transcription

1 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, march 2007, tsukuba, japan

2 Outline Carbon in the new planetary ecology Trends in CO 2 emissions Recent acceleration Global and regional patterns and drivers Land and ocean CO 2 sinks Future vulnerability Urbanisation Implications of the tragedy of the commons

3 Two nested ecologies 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 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

4 Carbon-climate-human system: forcing and response Records ( ) of: CO 2 emissions from fossil fuels Changing CO 2 concentrations in the atmosphere Changing global mean temperatures (from instrumental record with effects of urbanisation removed) FFemission to 2003 FFemission Global temperature CO CO now Marland, CDIAC Marland PersComm Jones et al, CRU LawDome 20yr MaunaLoa Temperature (deg C) Atmoapheric [CO2] (ppmv) Fossil Fuel Emission (GtC/y Emissions [CO2] 2 ppm/year Temperature 0.2 C/decade

5 Observed climate response Temperature For temperature and sea level, observed trends for 1990 to 2005 are at the upper edge of IPCC Third Assessment (2001) predictiions Sea level Rahmsdorf, Church et al. (2007) Science

6 Canadell, Le Quere, Raupach et al. (2007) PNAS (submitted) Global budget of atmospheric CO 2 Source from land use change Source from fossil-fuel emissions Ocean sink Atmospheric accumulation = F Foss + F LUC + F LandAir + F OceanAir : 45% of total emissions remain in atmosphere Land sink

7 Outline Carbon in the new planetary ecology Trends in CO 2 emissions Recent acceleration Global and regional patterns and drivers Land and ocean CO 2 sinks Future vulnerability Urbanisation Implications of the tragedy of the commons

8 Recent acceleration in CO 2 emissions Fossil-fuel CO 2 emissions in 2005: 7.9 PgC Growth rate in fossil-fuel CO 2 emissions (CDIAC): 1990 to 1999: ~1% per year 2000 to 2005: ~3% per year Canadell et al. (2007) PNAS (submitted) Raupach et al. (2007) PNAS (submitted)

9 CO 2 from fossil fuels: global trends Compare: actual emissions emissions scenarios stabilisation scenarios Scenarios underestimate actual emissions since 2000 Emissions growth has increased from 1% pa in 1990s to over 3% pa since 2000 Graph to appear in PNAS Raupach et al. (2007) PNAS (submitted)

10 Raupach et al. (2007) PNAS (submitted) CO 2 from fossil fuels: regional trends Graph to appear in PNAS

11 Drivers of emissions: population, energy, GDP Population (millions) Key to regions D3 D2 India China FSU D1 Japan EU USA GDP (market exchange rates) Graph to appear in PNAS Primary energy use [EJ/y]

12 Formalism Basic variables (extensive: proportional to size of a homogeneous region) F = fossil-fuel CO 2 emission P = population G = GDP E = primary energy use 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)

13 Raupach et al. (2007) PNAS (submitted) Drivers of global emissions Kaya Identity F G = P P Fossil-fuel CO 2 emission Population Per-capita GDP F G Carbon intensity of GDP World F (emissions) P (population) g = G/P h = F/G

14 Raupach et al. (2007) PNAS (submitted) Who contributes to fossil-fuel carbon? Depends on time scale (accumulation, current flux, current growth rate) Graph to appear in PNAS

15 Outline Carbon in the new planetary ecology Trends in CO 2 emissions Recent acceleration Global and regional patterns and drivers Land and ocean CO 2 sinks Future vulnerability Urbanisation Implications of the tragedy of the commons

16 Vulnerability of carbon pools NOW C 4 MIP = Coupled Climate Carbon Cycle Model Intercomparison Expt (Friedlingstein et al. 2006) Intercomparison of 11 coupled climate-carbon cycle models For all models, feedbacks => increased CO 2 more warming (by deg) higher AF (by ) Main carbon-climate feedbacks: ocean CO 2 uptake CO 2 fertilisation of land NPP climate effects on carbon release from land pools

17 Processes influencing global land-air C fluxes Drivers: A: atmospheric composition B: physical climate C: land use and land mgment In C4MIP Process Driver Sign of land-to-air flux (+, ) = (source, sink) A1 CO2 fertilisation A A2 Nutrient constraints on CO 2 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) C4 Woody encroachment / woody thickening C C5 Deforestation and land clearing (eg forest to savannah) C C + C6 Peatland and wetland drainage C + C7 Agricultural practices C ±

18 Vulnerability to release of frozen carbon A1 without frozen-c feedback A1 with frozen-c feedback 100 ppm Response of CO 2 C A (ppm) Response of temperature degc C F0 = 900 PgC (from permafrost area and permafrost soil C data) k FT = [y -1 K -1 ] (Anisimov et al 1999: warming of 2 degc over 100 y decreases permafrost by 25%) 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) T A (degc)

19 Outline Carbon in the new planetary ecology Trends in CO 2 emissions Recent acceleration Global and regional patterns and drivers Land and ocean CO 2 sinks Future vulnerability Urbanisation Implications of the tragedy of the commons

20 Global trends in urbanisation UN Development Program data (August 2006) World 1500 More Developed Population (million) Urban > 10M Urban 5M to 10M Urban 1M to 5M Urban 0.5M to 1M Urban < 0.5M Rural Less Developed Least Developed

21 August 2006 Populations of largest urban regions and cities 100 largest urban regions 1: Tokyo (35.2M) 100: Casablanca (3.1M) Total: 693M (10.7% of global) 60 largest cities 1: Mumbai (12.78M) 60: Pune (3.06M) Total: 351M (5.4% of global) Population (M) Tokyo region (35M) Populations of largest urban regions and cities (2005) Urban Regions Cities 2 We are talking about urban settlements of all sizes! Rank

22 Affluence and consumption per unit area NASA Earthlights composite

23 Urban and rural incomes: China Per capita income of urban and rural households in China, Heilig, G.K. (1999) Can China feed itself? A system for evaluation of policy options. IIASA. ( 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. Source: China Statistical Yearbook, Beijing, 1998 (p.325) Note: Constant prices.

24 The tragedy of the commons (Garrett Hardin, 1968) On a pasture open to all, each herdsman tries to maximise his gain by keeping as many cattle as possible on the commons. Eventually the commons become overgrazed. 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. So he adds one more animal. And so on, for each herdsman... "Freedom in a commons brings ruin to all". Hardin G (1968) The tragedy of the commons. Science 162, Reprinted in Kennedy D et al. (2006) Science Magazine's State of the Planet Island Press, Washington DC.

25 The tragedy of the commons (Garrett Hardin, 1968) "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) Hardin's examples: Exploitation of common resources (fish, forests,...) Population Pollution Hardin G (1968) The tragedy of the commons. Science 162, Reprinted in Kennedy D et al. (2006) Science Magazine's State of the Planet Island Press, Washington DC. Hardin's solution: Mutual coercion, mutually agreed upon by the majority of people affected

26 Beyond the tragedy of the commons: Two ways forward 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 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 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 Island Press, Washington DC.

27 Climate change as a tragedy of the commons Danger is well known: emissions of CO 2 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) "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) This is true of everyone, including any Australia-size part of China! After over 15 years of climate change awareness, we have: No agreed global emissions caps No agreed global regulatory institution, either collaborative or coercive Exploitation of individual commons benefit (atmosphere as a free waste dump) continues unabated, despite years of awareness of common threat

28 Four response dimensions Technical Broad portfolio: renewables, cleaner FF, conservation... A workable transition pathway that starts now Economic Market drivers: GH accounting, trading mechanisms 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 Cultural and social: building social capital Global: protection of the commons as a global ethical imperative Local: decoupling quality of life from consumption

29 Conclusion: Three turning points The Crossroads of Gaia The Earth System is fragile Humans are now major participants The Crossroads of Kyoto Our first, flawed effort to build global social capital The Crossroads of Robert Johnson Unmaking the devil's bargain with our Gaian inheritance of detrital carbon World F (emissions) P (population) g = G/P h = F/G

30 Hilary Talbot