Global Environmental & Global Environmental & Human Health IssuesHuman Health Issues

Molly Kile, ScDENVRE-115

Fall 2009

AnnouncementsAnnouncements

• More features added to the course website

http://isites.harvard.edu/icb/icb.do?keyword=k64179&pageid=icb.page286023

• Assessment of class participation will depend on in-class participation, live chat sessions, blog entries, and personal communications with teaching staff

• For book report can select texts from “Additional Books To Consider” in syllabus or one of your own choosing if given instructor approval.

• Pedagogical goal of assignments is to foster critical thinking which involves comparing, contrasting and synthesizing what one has learned which requires being open to new knowledge and actively reflecting on its meaning.– Homework #2 is due September 22– Use the drop box to submit your assignments. If you emailed in your

assignment you should go back and put it in the drop box.

Logistics of Distance EducationLogistics of Distance Education• Lecture is available as a live streaming feed during class period

and are also archived after processing (< 48 hrs)

• Chat room is monitored during class

• If you live outside of the New England area you must arrange for proctored midterm and final exam a minimum of two weeks prior to scheduled exam dates– http://www.extension.harvard.edu/2009-10/DistanceEd/how-it-

works/policy.jsp

Economic LiteracyEconomic Literacy

• There is no formal (only suggested) economics prerequisite for this course

• Check your economic literacy and review concepts by taking the “Economic Literacy Self Assessment” on the course website. You should be familiar with these terms and concepts before the lecture on October 13.

• If you need or want to review economic terminology you can use any undergraduate economics textbook or the “Guidelines for Preparing Economic Analyses” by the US EPA.– http://yosemite.epa.gov/ee/epa/eed.nsf/webpages/Guidelines.ht

ml

Agenda For TodayAgenda For Today

• Drivers of environmental issues

• Underlying Ecological Principles

• Demographic and Epidemiological Transition

• Linkage between human health and development

• Demographic dividend

Ecological Footprint ResultsEcological Footprint ResultsQuestion 5 If everyone lived like you, how many planets would we need?A. 1B. 2C. 3D. 4E. 5F. 6G. more than 6

Total

0% 5% 10% 15% 20% 25% 30%

   G.    F.    E.    D.    C.    B. A.

This means it takes 36 more months for the Earth’s ecosystems to regenerate what we are using in a single year.

Global Human FootprintGlobal Human FootprintAs of 2003, exceeded the Earth’s biocapacity by ~25% As of 2003, exceeded the Earth’s biocapacity by ~25%

(WWF)(WWF)

For how long can this go on?• Humanity’s demand will be twice the biosphere’s productive

capacity in 2050• A moderate business-as-usual scenario, based on United Nations

projections of slow, steady growth of economies and populations

Drivers of environmental Drivers of environmental issuesissues

POPULATION DRIVERPOPULATION DRIVERIn the past 200 years, the global population has increased exponentially

Math Behind Exponential Math Behind Exponential GrowthGrowth

Consider a country with 100 people, growing at 7% per year. In 10 years, the population will double to 200 people, in another 10 years it will double again to 400 people, etc (see graph)

How long will it take this country to reach 1 million?

0.00200,000.00400,000.00600,000.00800,000.00

1,000,000.001,200,000.001,400,000.001,600,000.001,800,000.00

0 20 40 60 80 100 120 140

Years

Pop

ulat

ion

t = ln [N(t)/N(0)] / r

t = ln (1,000,000/100)/0.07t = ln (10,000)/0.07t = 9.2103/0.07t = 131.5 years

Doubling Time (The Rule of 70)Doubling Time (The Rule of 70)

• The basic differential equation for exponential growth: dN/dt = rN, over the period from t=0 to t = the time period in question, where N is the quantity growing and r is the growth rate

• The integral of this equation is Nt = N0 x ert where N(t) is the size of a quantity after t intervals have elapsed, N(0) is the initial value of the quantity, e is the base of the natural logarithm, r is the average growth rate over the interval in question, and t is the number of intervals

• If one knows the final and initial values of N and the average growth rate, one can find the time it takes at that average growth rate for the quantity to grow from its initial value to the final value

t = ln [ N(t)/N(0) ] / r

• A special case is the doubling time, which is the time when N(t)/N(0) = 2. At that point rt = ln 2 = 0.69. If one knows the growth rate as a decimal fraction, then the Doubling Time = 0.69 / r.– This can be further simplified…the Rule of 70If the growth rate is given in percent, then 0.69 must be multiplied by

100, and the doubling time = 69/r. This can then be rounded up to 70. This simplifies to:

Amount of time for population to double = 70/rate expressed as a percentage

ExamplesExamples

1. How long would it take for a population to double if the growth rate is 3.5%?

Doubling Time

Time = 70/3.5 = 20 years

2. In a country where the GDP is growing at 4.5% per annum and the population is growing at 1.0 % per annum, how long will it take for the per capita GDP to double?

Doubling time = 70/(4.5%-1% ) = 70/3.5 = 20 years

3. In 1971, global population was 3.8 million and it is currently 6.8 million. What was the global population growth rate during this time frame?

Doubling Time

Time= 70/rate(%)36 years = 70/raterate = 70/36rate= 1.9%

AFFLUENCE & TECHNOLOGY AFFLUENCE & TECHNOLOGY DRIVERSDRIVERS

Global Income Distribution

Global distribution of income by economic Global distribution of income by economic classclass

Source: Sutcliffe, 2005. Department of Economic and Social Affairs.WP 2. United Nations

Influence of economic status on resource use

Consumer Preferences

• Increasing wealth changes pattern of demand and ability to afford reducing externalities

• Kuznets curve illustrates the relationship between economic development and environmental degradation

Economics & Environmental Economics & Environmental Degradation Degradation (Kuznet’s Curve)(Kuznet’s Curve)

Stage 1 Stage 2

Start ofindustrialdevelopment

Initiation ofemissionscontrol

Stabilizationof air quality

Stage 3 Stage 4

Improvement of air quality

High Technology applied

Low Level of development High

Development of air pollutionproblems in cities according to development status

WHO Guideline ornational standard

Stage 0

Relationship between air pollution problems in cities and the level of development. As a city experiences development, the air pollution problems in the city increase rapidly, before stabilizing and declining as air pollution controls are implemented (Source: Based on Haq et al, 2002; Peters 2003)

Examples of Kuznet’s CurveExamples of Kuznet’s Curve

Ehrlich Identity: I=PATEhrlich Identity: I=PAT

• Environmental Impact is a multiplicative product from small changes in Population, Affluence and Technology

• Mathematically represented as:

(I + ΔI) = (P + ΔP)(A + ΔA)(T + ΔT)

Divide through by the identity (1 + ΔI/I) = (1 + ΔP/P)(1 + ΔA/A)(1 + ΔT/T)

Where ΔI/I, ΔP/P, and ΔT/T is the percentage increase in impact, affluence and technology

Quantifying ImpactQuantifying Impact

• Example: Lead in gasoline from 1946 to 1968 in the US– Pop. increased 42%– Vehicle mile per capita doubled– Amount of lead per vehicle mile increased 81%

(I + ΔI/I) = (P + ΔP/P)(A + ΔA/A)(T + ΔT/T)

(1 + ΔI/I) = (1 + 0.42)(1 + 1.0)(1 + 0.81)

(1 + ΔI/I) = 5.14

ΔI/I = 5.14 – 1

=4.14

Or 414% increase in lead

Population Impact Depends on Underlying Distribution

6.0 millionMentally Deficient

6.0 millionMentally Gifted

Population Impact of Subclinical Lead Toxicity

9.4 millionMentally Deficient

2.4 millionMentally Gifted

57% Increase inMentally Deficient

Population

Underlying Ecological Underlying Ecological PrinciplesPrinciples

Carrying CapacityCarrying Capacity

• Ecological definition:– the number of individuals in a population that the

resource of a habitat can support

• Other definitions:– Point at which the birth rate equals the death rate– The number of individuals an environment can support

without significant negative impacts– The population size is constrained by whatever resource

is in shortest supply (Malthus)

Tragedy of the [Unregulated] Tragedy of the [Unregulated] CommonsCommons

Garrett HardinGarrett Hardin

“Picture a pasture open to all. It is to be expected that each herdsman will try to keep as many cattle as possible on the commons. Such an arrangement may work reasonably satisfactorily for centuries because tribal wars, poaching, and disease keep the numbers of both man and beast well below the carrying capacity of the land.”

What are the consequences of adding one more animal to my herd?

• “The population problem has no technical solution; it requires a fundamental extension in morality.”

Science 1968

OvershootOvershoot

• A rapidly growing population can exceed (overshoot) the ecological carrying capacity due to the “momentum” of its growth.

• Indicators of Overshoot– Deterioration in renewable resources – Rising levels of pollution– Growing demands by military and

industry to secure resources– Investment in human capital

postponed to meet immediate consumption demands

– Rising debt– Eroding goals for health and

environment – Growing instability in natural

ecosystems– Growing gap between rich and poor

Ecological EvidenceEcological Evidence

In 1944, 29 reindeer were introduced to St. Matthew Island.

In 1963, there were 6,000. One winter later, there were less

than 50. By 1980, there were none.

Klein, 1968

Human Population GrowthHuman Population Growth

Factors that influence human population growth:

• Fertility

• Age structure of population

• Mortality

FertilityFertility

• Birth rate is defined as the number of live births per 1,000 women aged 15-49 in a given year

• Replacement level fertility– Net reproduction rate of 1

• Every woman of childbearing age has 1 daughter

– Total fertility rate of 2.1• Every woman of childbearing age has 2.1 children

Fertility Rates Are Fertility Rates Are DecliningDeclining

Average number of children per woman

5.75.25.4

6.46.4

8.5

5.3

3.3

6.2

3.1

2.4 2.1

4.3

2.5

Egypt India Indonesia Iran Pakistan Turkey Yemen

1970-1975 2000-2005Source: United Nations, World Population Prospects: The 2004 Revision, 2005.

Four factors that influence Four factors that influence fertilityfertility

1. The proportion of women of childbearing age who are married or in a sexual union

2. The percent of women using contraception and the level of abortion

3. The proportion of women of childbearing age who currently are unable to conceive a child (usually from postpartum infecundity from breastfeeding)

4. Educational attainment of girls and women

Association Between Fertility and Association Between Fertility and Education of GirlsEducation of Girls

0

20

40

60

80

100

120

0 1 2 3 4 5 6 7 8

Percent of Girls Enrolled in Secondary School

Source: Population Reference Bureau, Population & Economic Development Linkages 2007 Data Sheet.

Total Fertility Rate

Association Between Fertility and Association Between Fertility and Female Labor Force ParticipationFemale Labor Force Participation

0

20

40

60

80

100

0 1 2 3 4 5 6 7 8

Female Labor Force Participation Rate 2004

Source: United Nations, World Population Prospects: The 2004 Revision, 2005; International Labor Organization, Yearbook of Labor Statistics 2006.

Total Fertility Rate 2000-2004

Association between fertility and Association between fertility and wealthwealth

6.4

4.9

4.1

4.9

3.2

2.42.8

2.4

1.4

Ghana 2003 Cambodia 2005 Colombia 2005

Poorest Quintile Middle Quintile Richest Quintile

Average Number of Children Born to a Woman During Her Lifetime

Source: ORC Macro, Demographic and Health Surveys.

2. Age Structure of a 2. Age Structure of a PopulationPopulation

• A large proportion of young people guarantees that population will continue to grow even with declining fertility

• Takes two or three generations (70-100 years) before each new birth is offset by a death

• Referred to as population momentum

Population MomentumPopulation MomentumThere is a growing population of women in their childbearing

years that will contribute to future world population growth even if fertility continues to decline

0.6

0.9

1.82.0 2.0

1.3

0

1

2

3

1950-1955 1970-1975 1990-1995 2010-2015 2030-2035 2045-2050

Bill

ion

s

0

1

2

3

4

5

6

Ch

ildre

n p

er

wo

ma

n

Women 15 to 49 Average number of children per woman

Source: United Nations, World Population Prospects: The 2004 Revision (medium scenario), 2005.

3. Mortality3. Mortality

• Death is the ultimate determinant of population growth

• Falling mortality precedes a decline in fertility

Death rate

Population growth rate

Birth rate

Time

Rat

e

How To Shift Causes of How To Shift Causes of MortalityMortality

• Improved sanitation and drinking water supplies

• Medical advances (vaccination, antibiotics)

• Social advances (improved nutrition, access to health care)

• Occupational Health & Safety (injury prevention, chemical safety)

• Infrastructure Improvements (roadways, housing, energy)

• Consumer Safety (injury prevention, chemical safety)

• Economic growth

Demographic TransitionDemographic Transition

Human HealthHuman HealthAnd DevelopmentAnd Development

Epidemiological TransitionEpidemiological Transitionthe study of factors affecting the health and illness of

populations • Conceptually describes the interaction

between causes of mortality, life expectancy and development

Mor

talit

y Ra

tes

Infectiousdiseases

Epidemiological Transition

Non-communicablediseases

Systematic Shift in Disease

Systematic Shift In DiseaseSystematic Shift In DiseaseM

orta

lity

Rate

s

Infectiousdiseases

Socio-Economic Development

Trauma

Type 2Diabetes

CHDCancers

PremisePremise

• Fertility has a fixed upper limit but not mortality so mortality is the fundamental factor that controls population dynamics

• Diseases and injuries control mortality

• Investment in public health shifts the causes of death (Epidemiological Transition) and this will influence population structure where women and children benefit the most

• During the late phase of the demographic transition when fertility and dependency rates fall countries can harness the demographic dividend when output per capita rises

Stages in Epidemiological Stages in Epidemiological TransitionTransition

1. The Age of Pestilence and Famine– Mortality is high and fluctuating no sustained

population growth– Life expectancy between 20-40 years

2. The Age of Receding Pandemics– Epidemics less frequent high population growth– Life expectancy between 30-50 years

3. The Age of Degenerative and Man-Made diseases– Mortality declines and stabilizes at a low level

fertility rate determines population growth– Life expectancy exceeds 50 years

Influence of Municipal Water on Influence of Municipal Water on MortalityMortality

Sewer system built & expanded

Reservoir/Aqueduct expansionsProtected watersheds

Public Health Benefits From Municipal Water Public Health Benefits From Municipal Water SupplySupply

• US from 1900-1940– Cholera and Typhoid Fever eliminated– Total mortality 140 to 20 per 100,000– Child mortality

130 to 60 per 1,000 live births – Life expectancy

16 years

• Cost-benefit analysis conducted by Cutler & Miller, 2005– 1:23 cost-benefit ratio – Every life saved cost $500* resulting in $11,500

gain* 2002 US$

The Age of Receding PandemicsThe Age of Receding Pandemics

Morbidity and mortality associated with level of developmentMorbidity and mortality associated with level of development

http://www.nytimes.com/2007/11/26/nyregion/26manhole.html

Age of Degenerative & Man-Made diseasesAge of Degenerative & Man-Made diseases

LEADING CAUSES OF DEATH, US 20021. Heart disease 28.5%2. Cancer 22.8%3. Stroke 6.7%4. COPD 5.1%5. Accidental injury 4.4%6. Diabetes

3.0%7. Influenza/Pneumonia

3.7%8. Alzheimer’s disease

2.4%9. Kidney disease 1.7%

The Changing Built Environment•Rapid population growth•Urbanization•Sprawl•Traffic•Sedentary life style•Changing diet

Less Density = More Driving Less Density = More Driving

Miles per capita– more than Miles per capita– more than doubled in one generationdoubled in one generation

Miles per Capita: 1960 to 1995 From 4000 to 9200 VMT per person

Obesity* Trends Among U.S. AdultsObesity* Trends Among U.S. AdultsBRFSS, 2003BRFSS, 2003

(*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person)

No Data <10% 10%–14% 15%–19% 20%–24% ≥25%

Case Study: People’s Case Study: People’s Republic of ChinaRepublic of China

Harnessing a Demographic DividendHarnessing a Demographic Dividend

• China began investing in social development projects including education and health care under Maoist Government

– 1952-1982: Invested in rural health through network of clinics and ‘barefoot’ doctors

• Infant mortality decreased from 200 to 34/1000 live births• Life expectancy rose from 35 years to 68 years• Fertility rates declined from 6 births/woman (1970) to 3

birth/woman(1979) to “one child” policy in 1980• Universal primary education

– 1980s saw major economic reform characterized by deregulation and liberalization opened up their economies to international trade and attracted foreign investment.

• People born in the 1965 cohort with improved health care and education are now in their 40’s and in their productivity peak

• Harnessed demographic dividend due to low ratio of dependents to adults below 65

• 2005 GDP growth was 9%

• 1/3 of income growth per capita in SE Asia (about 2 percentage points) during 1965-90 is attributable to the independent influence of changes in age structure Cover from the book by David Cork and Susan Lightstone:

The Pig and the Python, How to Prosper from the Aging Baby Boom

http://www.iiasa.ac.at/Research/LUC/ChinaFood/data/anim/pop_ani.htm

Period of Potential Demographic BonusPeriod of Potential Demographic Bonus

• Countries with increasing numbers of working-age adults relative to dependent elderly and children have an opportunity to increase employment, investment, and savings

• Whether or not the demographic bonus is realized depends on economic policies and economic opportunities

1989 2011

1980 2008

1986 2050

1964 2024

1974 2047

1965 2014

1969 2037

1965 2013

2005 2050

1985 2048

2014 2050

1950 1975 2000 2025 2050

Chad

Ghana

Malawi

China

India

South Korea

Bolivia

Brazil

Guatemala

Czech Republic

Poland

Source: Population Reference Bureau, Population & Economic Development Linkages 2007 Data Sheet.

SummarySummary

• Environmental Impact is a multiplicative function of population, affluence and technology. These drivers can have a neutral, positive or negative impact on the environment.

• Population growth is a central issue in sustainable development due to concerns about ecological carrying capacity of species and it is considered a problem with a non-technical solution

• Fertility has a fixed upper limit (and is controlled effectively by education of girls/women) but not mortality so mortality ultimately controls population growth and demographics

• Causes of mortality are associated with level of development

• Investment in public health shifts the causes of death (Epidemiological Transition) and this will influence population structure (Demographic Transition) where women and children benefit the most

• When fertility and dependency rates fall countries can harness the demographic dividend when output per capita rises

Terminology and Concepts To Terminology and Concepts To ConsiderConsider

1. Erhlich Identity

2. Kuznet’s Curve

3. Tragedy of the Commons

4. Carrying Capacity

5. Overshoot and Population Momentum

6. Demographic Transition

7. How patterns of disease influence demographics (Epidemiological Transition)

8. Role of fertility, age structure and mortality in population growth

9. Population momentum can lead to demographic dividend

ResourcesResources

• “Improving the health of the world's poor” BMJ No 7107 Volume 315– http://www.bmj.com/archive/7107/7107e1.htm

• Population health in transition by John Caldwell– http://whqlibdoc.who.int/bulletin/2001/issue2/79(2)159-170.pdf

• World Health Reports– http://www.who.int/whr/en/

• Preventing disease through healthy environments: Towards an estimate of the environmental burden of disease– http://www.who.int/quantifying_ehimpacts/publications/preventingdiseas

e.pdf• Health and Economic Growth: Findings and Policy Implications.

Edited by G. López-Casasnovas, B. Rivera and L. Currais. MIT Press– http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=10711

• Why Has China’s Economy Taken Off Faster than India’s? David E. Bloom, David Canning, Linlin Hu, Yuanli Liu, Ajay Mahal, and Winnie Yip– http://www.hsph.harvard.edu/pgda/Bloom_Canning_China_India.pdf