1 / 32

The country level: sustainability and age structure

The country level: sustainability and age structure. The most important issue that links age structure to potential problems of sustainability is the pension system

brandyl
Télécharger la présentation

The country level: sustainability and age structure

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The country level:sustainability and age structure • The most important issue that links age structure to potential problems of sustainability is the pension system • The equilibrium of a pay-as-you-go pension system depends on the fact that the total amount of contributions is equal to the total amount of pensions paid in any given year

  2. The country level:sustainability and age structure • Demographically, this depends on the stability of the ratio between population in working age and population in retirement age • ‘Support ratio’: how many persons aged 15-64 are there for a person aged 65 and over?

  3. ‘Support ratio’ Italy, Germany, Spain,UN projections 2002

  4. The country level:sustainability and age structure • If the support ratio decreases, solutions: • Increase retirement age • Increase labour force participation (i.e. of women) • Decrease level of pensions • Increase level of contributions • At the level seen, the development is not sustainable

  5. The country level:sustainability and age structure • The main reason is the decrease in fertility • Second reason the increase in longevity

  6. TFR (number of children per woman) Italy, Germany, Spain

  7. Life expectancy at age 65 Italy, Spain (women)

  8. The country level:sustainability and age structure • “Lowest-low” fertility, defined when the average number of children per woman in a year (“period” TFR) drops below 1.3 has emerged in Europe in the 1990s (Kohler, Billari, Ortega, 2002) • Forerunners: Italy & Spain. Then Central & Eastern Europe, Former USSR

  9. The country level:sustainability and age structure • Long-term sustainable solution: • Increase in fertility combined with • Increase in immigration • To be in equilibrium, TFR should be close to 2.1 (e.g. 1.8) and immigration compensate for the difference (close to U.K., U.S. solution) • Of course, in the meanwhile medium- short-term solutions

  10. Net migration rate (% of the population) Italy, Spain

  11. The global level • World’s population is at a level that has never been reached in the past • Today’s counts are pretty close to 6.4 billion individuals (U.S. Census Bureau World Population Clock) • Is population a “bomb”?

  12. The global level Billions 12 11 2100 10 9 Modern Age Old 8 Iron Middle Bronze Stone Age New Stone Age Ages Age Age 7 Future 6 2000 5 4 1975 3 1950 2 1900 1 1800 Black Death — The Plague 2000 1+ million 7000 6000 5000 3000 1000 A.D. 4000 A.D. A.D. A.D. A.D. A.D. years B.C. B.C. B.C. B.C. B.C. B.C. B.C. 1 1000 2000 3000 4000 5000

  13. The global level • Maybe pure growth problems are not the most relevant ones for the future • The demographer Wolfgang Lutz and colleagues in 2001 (‘Nature’) proclaimed ‘The end of world population growth’

  14. The global level

  15. Modeling population dynamics • Population dynamics can be modeled in simple but meaningful and didactical ways • Exponential growth • Logistic growth • Logistic growth with time-varying carrying capacity

  16. Exponential growth • T.R. Malthus (1766-1834) • 1798: An Essay on the Principle of Population • “…the human species would increase in the ratio of -- 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, etc. and subsistence as -- 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.”

  17. Exponential growth • The “Population Bomb”

  18. Exponential growth

  19. Logistic growth • Back to Malthus (a different reading): • “…That population cannot increase without the means of subsistence is a proposition so evident that it needs no illustration...” • Pierre Verhulst (1845): logistic growth. Population cannot grow above a certain level (‘carrying capacity’)

  20. Logistic growth (discrete time) • Explicit modeling of the carrying capacity (K) • Limits to growth • K is an asymptote • Note: potential chaotic dynamics (Robert May, ‘Nature’, 1976)

  21. Logistic growth (discrete time)

  22. Logistic growth with time-varyingcarrying capacity • The realism of the model can be improved, including ‘demographic transitions’ • K may vary over time because e.g. of innovation

  23. Logistic growth with time-varyingcarrying capacity

  24. Deevey’s (1960) graph(Scientific American – note the log scale)

  25. …real data on the log, log scale

  26. Modeling environmental impact and population • Paul Ehrlich and John Holdren (1971), “Impact of Population Growth”, Science; also Barry Commoner • IPAT Model

  27. I=PAT • Environmental impact (I) is a function of: • Population (P) • Affluence (A) • Technology (T) • In fact, • A is usually expressed as production per capita (Y/P) • T is usually expressed as impact per unit of production (I/Y)

  28. I=PAT • This model can be used to decompose the role of the three factors (P, A, T) in shaping environmental impact • E.g. Energy use • Technology (& technology transfers) are the keys to reduce environmental impact!

  29. I=PAT (McKellar et al., 1995)

  30. Bibliography • Joseph A. McFalls Jr., 2003, Population: a lively introduction, Population Bulletin, 58, 3, Population Reference Bureau, Washington D.C. • Massimo Livi Bacci, 2001, A Concise History of World Population, Blackwell Publishing, Malden • World Commission on Environment and Development, 1987, Our Common Future, Oxford University Press, Oxford • Luis Rosero-Bixby & Alberto Palloni, 1998, Population and Deforestation in Costa Rica, Population and Environment, 20: 149-185 • Richard Jackson & Neil Howe, 2003, The 2003 Aging Vulnerability Index, Center for Strategic and International Studies and Watson Wyatt Worldwide, Washington, D.C.

  31. Bibliography • Kohler, Hans-Peter, Francesco C. Billari & José Antonio Ortega, 2002, The Emergence of Lowest-Low Fertility in Europe During the 1990s, Population and Development Review 28: 641-680 • Wolfgang Lutz, Warren Sanderson & Sergei Scherbov, 2001, The end of world population growth, Nature 412: 543-545 • Robert May, 1976, Simple mathematical models with very complicated dynamics, Nature 261: 459-467 • Edward S. Deevey Jr., 1960, The Human Population, Scientific American 203: 194-204 • Paul R. Ehrlich & John P. Holdren, 1971, Impact of population growth, Science 171: 1212-1217 • F. Landis MacKellar, Wolfgang Lutz, Christopher Prinz & Anne Goujon, 1995, Population, Households and CO2 Emissions, Population and Development Review 21: 849-865

More Related