a probabilistic approach to exploring global dynamics nicky grigg, fabio boschetti, markus brede,...

A probabilistic approach to exploring global dynamics

Nicky Grigg, Fabio Boschetti, Markus Brede, John Finnigan

CSIRO, Australia

AIMES Open Science Conference, Edinburgh

11 May 2010

CSIRO. A probabilistic approach to exploring global dynamics

What, how and why?

• What:• Interactions: population, carbon emissions, economy

• How:• Low dimensional dynamic model

• Rates estimated from probability distributions fitted to UN datasets

• Ensembles of model runs to capture uncertainty and variability

• Why:• Trial probabilistic approach

• Qualitative insights, informed by quantitative dynamics

Model overview

CSIRO. A probabilistic approach to exploring global dynamics

Cumulative emissions

Population GDP

birthrate

deathrate

energy use per capita

GDP per capita

intrinsic growth rate

Peak temperature change

carbon intensity of energy use

Damagerate

State variables

CSIRO. A probabilistic approach to exploring global dynamics

Cumulative emissions

Population GDP

birthrate

deathrate

energy use per capita

GDP per capita

intrinsic growth rate

Peak temperature change

carbon intensity of energy use

Damagerate

Rates inferred from probability distributions

CSIRO. A probabilistic approach to exploring global dynamics

Cumulative emissions

Population GDP

birthrate

deathrate

energy use per capita

GDP per capita

intrinsic growth rate

Peak temperature change

carbon intensity of energy use

Damagerate

Derived quantities

CSIRO. A probabilistic approach to exploring global dynamics

Cumulative emissions

Population GDP

birthrate

deathrate

energy use per capita

GDP per capita

intrinsic growth rate

Peak temperature change

carbon intensity of energy use

Damagerate

Scenarios

CSIRO. A probabilistic approach to exploring global dynamics

Cumulative emissions

Population GDP

birthrate

deathrate

energy use per capita

GDP per capita

intrinsic growth rate

Peak temperature change

carbon intensity of energy use

Damagerate

Model overview

CSIRO. A probabilistic approach to exploring global dynamics

Cumulative emissions

Population GDP

birthrate

deathrate

energy use per capita

GDP per capita

intrinsic growth rate

Peak temperature change

carbon intensity of energy use

Damagerate

CSIRO. A probabilistic approach to exploring global dynamics

Birth rate vs GDP per capita

Data from http://unstats.un.org and http://data.un.org

CSIRO. A probabilistic approach to exploring global dynamics

Birth rate vs GDP per capita

CSIRO. A probabilistic approach to exploring global dynamics

Death rate vs GDP per capita

Data from http://unstats.un.org and http://data.un.org

CSIRO. A probabilistic approach to exploring global dynamics

Death rate vs GDP per capita

CSIRO. A probabilistic approach to exploring global dynamics

Energy use per capita vs GDP per capita

Data from http://unstats.un.org and http://data.un.org

CSIRO. A probabilistic approach to exploring global dynamics

Energy use per capita vs GDP per capita

Modelled historical distributions: population

CSIRO. A probabilistic approach to exploring global dynamics

* World population

Modelled historical distributions: cumulative emissions

CSIRO. A probabilistic approach to exploring global dynamics

* World cumulative emissions

Modelled historical distributions: world GDP

CSIRO. A probabilistic approach to exploring global dynamics

* World GDP

Mitigation

CSIRO. A probabilistic approach to exploring global dynamics

CSIRO. A probabilistic approach to exploring global dynamics

Climate damages

076.2

9.6211ln

ETpeak

Committed peak temperature change due to cumulative emissions:

(Raupach et al, 2010)

Climate damages

CSIRO. A probabilistic approach to exploring global dynamics

Relationship between damage rate and Tpeak:

Climate damages

CSIRO. A probabilistic approach to exploring global dynamics

Relationship between damage rate and Tpeak:

Proportion of runs with Tpeak < 2˚C

CSIRO. A probabilistic approach to exploring global dynamics

Mitigation completed sooner

Steeper onsetof damages

Proportion of runs with Tpeak < 2˚C

CSIRO. A probabilistic approach to exploring global dynamics

Mitigation completed sooner

Steeper onsetof damages

CSIRO. A probabilistic approach to exploring global dynamics

Proportion of runs with rising GDP per capita

Gentler onsetof damages

Mitigation completed sooner

CSIRO. A probabilistic approach to exploring global dynamics

Proportion of runs with rising GDP per capita

Gentler onsetof damages

Mitigation completed sooner

CSIRO. A probabilistic approach to exploring global dynamics

Proportion of runs withTpeak < 2˚C AND rising GDP per capita

Gentler onsetof damages

Mitigation completed sooner

Population <10 billion only

CSIRO. A probabilistic approach to exploring global dynamics

Gentler onsetof damages

Mitigation completed sooner

Max allowable energy use per capita

CSIRO. A probabilistic approach to exploring global dynamics

Gentler onsetof damages

Mitigation completed sooner

CSIRO. A probabilistic approach to exploring global dynamics

Energy use per capita vs GDP per capita

Data from http://unstats.un.org and http://data.un.org

Conclusions

• Data-driven probabilistic approach:• Uses more of the information inherent in datasets

• Allows propagation of variability and uncertainty

• Forward model to 2100 generates distributions of trajectories consistent with system evolving under realistic rates

• Probability distributions are more informative than single trajectories.

• Qualitative dynamics:• Surfaces in mitigation-damage space: steep boundary between

‘poverty trap’ and ‘good life’.

• Population-energy patterns within mitigation-damage scenario.

• Applicability more broadly• Framework suitable for studying other systems in which

environmental limits interact with population and economy.

CSIRO. A probabilistic approach to exploring global dynamics

Contact UsPhone: 1300 363 400 or +61 3 9545 2176

Email: enquiries@csiro.au Web: www.csiro.au

Thank you

CSIRO Land and WaterDr Nicky Grigg

Phone: +61 2 6246 5569Email: nicky.grigg@csiro.au

Model assumptions

• Population (P):• birth and death rates.

• Cumulative carbon dioxide emissions since1751 (E)• population size

• energy use per capita

• carbon intensity of energy supply.

• GDP (A):• Endogenous and population-related growth rates

• Climate feedback on GDP:• Global peak temperature change is a function of cumulative carbon

dioxide emissions.

• Temperature changes damage the economy.

CSIRO. A probabilistic approach to exploring global dynamics

CSIRO. A probabilistic approach to exploring global dynamics

Model equations: population

PkPkdt

dPdeathbirth

Population (P)

births/year deaths/year

kbirth is the birth rate per capita (births/person/year)kdeath is the death rate per capita (births/person/year)

Birth and death rates change over time and are a function of GDP per capita

CSIRO. A probabilistic approach to exploring global dynamics

Model equations: cumulative emissions

Pckdt

dEenergy

Cumulative emissions since 1751 (E)

c is the carbon intensity of energy (gC/MJ)kenergy is the rate of energy use per capita (MJ/person/year)P is the population

Energy use per capita varies over time and is a function of GDP per capita.Carbon intensity per MJ changes over time as an exogenously prescribed mitigation trajectory

CSIRO. A probabilistic approach to exploring global dynamics

Model equations: GDP

AkAkAkt

AAP damage2A2Ad

d

Climate-related damage rate

GDP (A)

Population-related GDP growth rate

Intrinsic GDP growth rate

t

P

Pk AP d

d2

= 0 : no population impact on GDP growth

= 1 : population impact on GDP growth rate