Pierluigi Crescenzi PRO
Professor at GSSI, L'Aquila
Living on a
finite earth
Pierluigi Crescenzi
Gran Sasso Science Institute
July 4, 2023
What can a computer
scientist do?
Joint work with Emanuele Natale, Paulo Bruno De Sousa Serafim, Hicham Lesfari, and Aurora Rossi
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
Living on a finite earth
World 2
AEF Web-conference
July 4, 2023
- Jay Forrester, World dynamics, 1971
- Application of system dynamics analytical framework
- Framework developed in the fifties
- Basically, systems of ordinary differential and algebraic equations
- Application of system dynamics analytical framework
- World 2 model
- It models the interrelationships between world population, industrial production, pollution, natural resources, agriculture and quality of life
- The objective is not to model each sector exactly, but to understand the effects of the evolution of all the variables on certain "key" variables
Population
Pollution
Agriculture
Resources
Quality of life
Capital
Living on a finite earth
World 2
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
Living on a finite earth
World 2
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
- Why model the world?
- We don't expect the model to predict the values of all variables exactly, but we do expect to see the main trends
- More importantly, we can see the effects of a specific policy on these trends
Living on a finite earth
World 3
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
- Donella Meadows et al, The limits to growth, 1972
- Dennis Meadows et al, Dynamic of growth in a finite world, 1974
- World 3 model
- Evolution of the World 2 model
- Described very precisely in the second book
- All DYNAMO code listed, commented and explained
- Updated and tested many times over the past 50 years
- Gaya Herrington, Update to limits to growth: Comparing the World3 model with empirical data, 2021
- World 3 model
Living on a finite earth
World 3
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
Living on a finite earth
World 3
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
Living on a finite earth
World 3
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
Living on a finite earth
World 3
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
"To stabilize the population, the desired completed family size is reduced to 2 children per family in 1975. The growth in industrial capital is reduced in 1990 by reinvesting only enough industrial output to keep industrial output per capita at a constant level. In addition, new recycling and pollution control technologies are developed, capital lifetimes are increased, and social choices of output forms are shifted toward a preference for food and services." (Meadows, 1974)
- Sandrine Dixson-Declève et al, Earth for All. A Survival Guide for Humanity, 2022
- Jorgen Randers and David Collste, The Earth4All model of human wellbeing on a finite planet towards 2100, 2022
- Earth4All model
- Evolved in fifteen years
- Not precisely described in the second book
- Code Vensim and Stella available
- Both Vensim and Stella are proprietary software
- Earth4All model
Living on a finite earth
Earth for all
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
- Focus on the average well-being index
- Worker disposable income per person – after tax
- Public spending per person
- The level of inequality
- Observed global warming
- Perceived progress
Living on a finite earth
Earth for all
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
Living on a finite earth
Earth for all
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
Living on a finite earth
Earth for all
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
- The Giant Leap
- Eliminate global poverty
- Use new growth models: more plan less market
- Stop climate change
- Replace fossils with wind and sun, efficiency, and CCS
- Halt biodiversity decline
- Introduce regenerative agriculture to protect remaining forests
- Stop population growth
- More education, health, contraception and opportunity to women
- Reduce inequality
- Make the rich pay for higher wellbeing for the working majority
- Eliminate global poverty
Living on a finite earth
Earth for all
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
Living on a finite earth
Earth for all
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
Dynamique du monde
WorldDynamics.jl
- Julia package in collaboration with Paulo De Sousa Serafim, Hicham Lesfari, Emanuele Natale, Aurora Rossi
- Open-source for integrated assessment modeling
- Implements all the models described
- Main objectives
- Transparency
- Modularity
- Documentation
- Ability to use all the firepower of the Julia community
- Scientific computing
- Data and graph mining
- Machine learning
- https://github.com/worlddynamics/WorldDynamics.jl
What can a computer scientist do?
WorldDynamics.jl
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
Dynamique du monde
WorldDynamics.jl
- Transparency
- All code is open-source
- Not only the model implementation
- Also the differential equation system solver
- All used functions
- In the case of Vensim, we could not know the source code of one function
- Still unknown...
- Work in progress: Vensim to WorldDynamics.jl translator
What can a computer scientist do?
WorldDynamics.jl
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
Dynamique du monde
WorldDynamics.jl
- Modularity
- ModelingToolkit.jl
- A composable graph transformation system for equation-based modeling
- ModelingToolkit.jl
What can a computer scientist do?
WorldDynamics.jl
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
ODE system \(1\)
ODE system \(2\)
ODE system \(k\)
...
Composition
Global ODE system
- It allows to work on one sub-model independently of the others
- Connection between variables can be done automatically
Dynamique du monde
WorldDynamics.jl
- Documentation
What can a computer scientist do?
WorldDynamics.jl
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
Dynamique du monde
WorldDynamics.jl
- Graph mining example
- Dependency graph
- Nodes: variables
- Arcs \((v_1,v_2)\) if \(v_2\) is in right-hand side of \(v_1\)
- 484 nodes, 810 arcs
- Density: 0.0035
- Largest strongly connected component
- 355 nodes (contains all variables of plots)
- Node with maximum indegree (20): Population
- 55 with indegree 0 (output variables)
- Node with maximum outdegree (7): Government net income
- 38 with outdegree 0 (input variables)
- Dependency graph
What can a computer scientist do?
WorldDynamics.jl
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
Dynamique du monde
WorldDynamics.jl
- Machine learning
- Universal differential equations
- Mixing scientific models with data-driven machine learning approaches
- Wide variety of applications can be phrased and efficiently handled through the UDE
- Example: automatically discovering biological mechanisms
- Universal differential equations
What can a computer scientist do?
WorldDynamics.jl
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
Pierluigi Crescenzi
Réunion Hosigra/Tempogral
AEF Web-conference
July 4, 2023
- Jay W. Forrester, World dynamics, Pegasus Communications, 1971
- Donella H. Meadows, Dennis L. Meadows, Jørgen Randers, William W. Behrens Ill, The limits to growth, Potomac Associates, 1972
- Dennis L. Meadows, William W. Behrens Ill, Donella H. Meadows, Jørgen Randers, Erich K.O. Zahn, Dynamics of world in a finite world, Wright-Allen Press , 1974
- Alexander L. Pugh, DYNAMO user's manual, Hassell Street Press, 2021
- Gaya Herrington, Update to limits to growth: Comparing the World3 model with empirical data. Journal of Industrial Ecology, 25, 614–626, 2021
- Sandrine Dixson-Decleve, Owen Gaffney, Jayati Ghosh, Jørgen Randers, Johan Rockstrom, Per Espen Stoknes, Earth for All: A Survival Guide for Humanity, New Society Publishers, 2022
- Jørgen Randers, David Collste, The Earth4All model of human wellbeing
on a finite planet towards 2100, 2022 - Yingbo Ma, Shashi Gowda, Ranjan Anantharaman, Chris Laughman, Viral B. Shah, Christopher Rackauckas, ModelingToolkit: A composable graph transformation system for equation-based nodeling, CoRR abs/2103.05244, 2021
- Christopher Rackauckas, Yingbo Ma, Julius Martensen, Collin Warner, Kirill Zubov, Rohit Supekar, Dominic Skinner, Ali Jasim Ramadhan, Universal differential equations for scientific machine learning, CoRR abs/2001.04385, 2020
- All plots produced by using the WorldDynamics.jl package
- https://vensim.com/software/
- https://www.iseesystems.com/store/products/stella-architect.aspx
- https://julialang.org/
- https://github.com/JuliaGraphs/Graphs.jl
References
Living on a finite earth
By Pierluigi Crescenzi
Private
Living on a finite earth
What can a computer scientist do?