how many people can the earth support?

2007 Fall Lecture 6 SCIE 103 Life Sciences 1

How many people can the Earth support?

The World at Night


How many people can the Earth support?

North America at Night


Human Population Growth and Consumption Each year, about 90 million new people are added to the planet.

This rate of growth will swell our population from today’s 6.1 billion to about 8.5 billion by 2025. At present growth rates, global population will be 40 billion by 2100.

The United Nations estimates, however, that growth rates will drop and world population will be 11.2 billion by 2100. This is still more than double today’s total.

Asia and Africa are adding more people each year than other continents, even though the percentage of people they add is not as high as in some countries. The huge number of people currently living on these continents translates into a large number of people added even with relatively low growth rates.

For example, China’s annual growth rate is only 1.2 percent, but the country’s population base of 1.2 billion people means that there is a net increase in China’s population of 15 million people every year. Population growth in Asia and Africa puts tremendous pressure on wildlife habitat on those continents.


Country Capital Area Population No. People / km2

1 China Beijing 9,596,960 1,313,973,713 137

2 India New Delhi 3,287,590 1,095,351,995 333

3 United States Washington, D.C. 9,629,091 298,444,215 31

4 Indonesia Jakarta 1,919,440 245,452,739 128

5 Brazil Brasília 8,511,965 188,078,227 22

6 Pakistan Islamabad 803,940 165,803,560 206

7 Bangladesh Dhaka 144,000 147,365,352 1023

8 Russia Moscow 17,075,200 142,893,540 8

9 Nigeria Abuja 923,768 131,859,731 143

10 Japan Tokyo 377,835 127,463,611 337

11 Mexico Mexico City 1,972,550 107,449,525 54

12 Philippines Manila 300,000 89,468,677 298

13 Vietnam Hanoi 329,560 84,402,966 256

14 Germany Berlin 357,021 82,422,299 231

15 Egypt Cairo 1,001,450 78,887,007 79

16 Ethiopia Addis Ababa 1,127,127 74,777,981 66

17 Turkey Ankara 780,580 70,413,958 90

18 Iran Tehran 1,648,000 68,688,433 42

19 Thailand Bangkok 514,000 64,631,595 126


How many people can the Earth support? If the Earth is not over-populated and the population continues to

grow, how many people can it support? Lifestyles and Per Capita Consumption

Humanity’s impact on the natural world can be understood by looking at the relationships between population size, per capita consumption, and lifestyles.

Multiplying the number of people times their rate of consumption gives the total human impact on the Earth.

Lifestyles determine per capita consumption. Affluence and technology determine possible lifestyles.

As a result, per capita consumption varies dramatically between humans depending on their affluence, access to technology, and the lifestyle they either choose or are forced to live.


How many people can the Earth support? Impact = Population x Affluence x Technology The term ‘affluence’ demands a value judgement about what is

‘affluent’ and what is not. It implies that subsistence consumption has no impact on the environment, when in fact all levels of consumption, even of hunter-gatherers, have some impact.

Environmental impact = Population x Consumption per person x Impact per unit of consumption

Impact can refer to any one of our three main forms of interaction with the environment: our use of primary resources from minerals to water and land; our physical occupation of space; or our output of pollutants.

The formula makes it clear that, for any given level of consumption per person or technology, higher population means higher environmental impact. Fewer people mean lower total consumption and waste.


How many people can the Earth support? To assess what contribution population makes to increases in

environmental damage - to try to assign relative blame - we have to look at changes over time. What we need is some measure of the share of each of our three elements in overall impact. If all three are pushing upwards, we can simply express the change in each one in turn as a percentage of the total change. So here:

Population impact = (annual % change in population x 100) / (annual % change in use of resource or output of pollutant)

Sometimes one or more of the three factors may be tending to reduce environmental impact. We can distinguish between upward and downward pressures by ‘scoring’ the upward pressures out of +100%, and the downward pressures out of -100%.


How many people can the Earth support? Let’s take the case of the expansion of agricultural land. This is not

merely physical occupation of space and use of the land resource. It is a prime source of environmental damage, cutting down forests, draining wetlands, ploughing up natural grassland, replacing natural ecosystems of high species diversity with artificial ones of low diversity.

What share in the increase in farmland we can attribute to population growth?

Between 1961 and 1985, population expanded by 2.3% a year in developing countries. Agricultural production rose by 3.3%. So production per person, which we can take as our consumption factor, rose by 0.9%. Farmland, meanwhile, expanded by only 0.6% a year. The farmland used per unit of agricultural production - the impact per unit of consumption - actually declined by 2.6% annually, because yields were increasing. Technology in this case exerted a downward pressure on environmental impact, at least in terms of land used. Only population and consumption exerted upward pressure.

In this case we can say that population growth accounted for +72% of the growth of farmland, and increase in consumption per person for +28%. Technology gets a score of -100%, since it was the only one of the three factors pushing towards lower use of farmland.


How many people can the Earth support? How much do we consume now?

“Human beings use 40 percent of annual terrestrial plant growth,

60 percent of accessible freshwater runoff, and 35 percent of the ocean’s continental shelf

productivity.” [from Stuart Pimm’s The World According to Pimm: a

scientist audits the Earth (2001)]


Consumption Support Consumption as measured by our “ecological footprint” which

represents the productive area of the Earth required to support the lifestyle of one individual in a given population: U.S.A. 30.2 acres per person (1 acre ~ 4000 m2) Germany 15.5 Brazil 6.4 Indonesia 3.7 Nigeria 3.2 India 2.6

In other words, on average, each American consumes ~10 times more of the worlds resources than an average person in India.

Population is not the only determinant of impact on the environment. The rate at which people consume resources is critical. The United States has a particularly heavy impact on resources because of its high consumption rate, even though its population is relatively low. For example, the environmental impact of a human baby born in the United States is 35 times that of one born in India, and 140 times that of a baby born in Bangladesh.


Sustainable Consumption

The use of services and related products which respond to basic needs and bring a better quality of life while minimizing the use of natural resources and toxic materials as well as the emissions of waste and pollutants over the life-cycle of the service or product so as not to jeopardize the needs of future generations.



The importance of the social element of sustainable consumption has been increasingly emphasised over the last few years. UNDP (United Nations Development Programme) formulated the following principles for what consumption should be: “shared (ensuring basic needs for all), strengthening (building

human capabilities), socially responsible (the consumption of some should not compromise the wellbeing of others) and sustainable (without mortgaging the choices of future generations)”.

And UNEP (United Nations Economic Programme) observed that “ … it is becoming more and more evident that consumers are

increasingly interested in the “world behind” the product they buy: they want to know how and where and by whom the product has been produced”.



Options available for individual consumers to cut down their impact on the environment can simply be listed as follows: purchase and use fewer resources (for instance energy

and water saving); purchase and use more eco-efficient resources (for

instance solar electricity); purchase and use fewer products (for instance one

television set in stead of three); purchase and use more eco-efficient products and services

(for instance public transport); produce less waste (avoid packaging and contribute to

recycling schemes).



The category “producers” includes local or national governments as well – in so far these supply infrastructure, public transport and other public goods - and non-governmental organisations, for instance offering access to national parks. Over-arching role for governments is to design and implement policies in such a way that both consumers and producers act accordingly.


Sustainable ConsumptionACTOR ACTION

POLICY INSTRUMENT

EXAMPLE

CONSUMERSUse fewer resources

Economic Energy tax

Regulatory Speed limits in air polluted areas

Social Water saving campaign

Other policy influences Public health campaigns

CONSUMERSUse better resources

Economic Solar power subsidy

RegulatoryTemporary bans on using drinking water for gardens

Social Green electricity schemes

Other policy influences Physical planning regulations for local windmills

CONSUMERSUse fewer goods

Economic Motor vehicle tax

Regulatory Free motorway zones for car sharing

Social Promotion of library

Other policy influences Tax incentives influencing household size

CONSUMERSUse better goods

Economic Leaded-petrol taxes

RegulatoryEnvironmental standards in car maintenance schemes

Social Promotion campaigns for fair trade coffee

Other policy influencesAgricultural policies promoting industrial food products



POLICY INSTRUMENT

EXAMPLE

CONSUMERS Produce less waste

Economic Recycle premiums

RegulatoryLocal waste separation regulations

SocialAwareness campaigns on avoiding packaging

Other policy influences Safety and hygiene regulations

PRODUCERS Improve production process

Economic Tradable permits

Regulatory Emission standards

Social Codes of conduct

Other policy influences Social legislation

PRODUCERSSupply better goods and info

Economic Research grants

RegulatoryConstruction standards for e-efficient houses

Social Voluntary Reporting Initiatives

Other policy influencesInformation technology leading to greater transparency

PRODUCERSSupply new goods or services

Economic Taxes/subsidies

Regulatory Product standards

Social Network building of pioneers

Other policy influences Labour cost policies



ACTOR ACTIONPOLICY INSTRUMENT

EXAMPLE

RETAILERSPractice good housekeeping (water, energy, waste)

Economic Taxes/subsidies

Regulatory Waste regulations

SocialVoluntary initiative (for instance green supermarkets)

Other policy influences Physical planning

RETAILERSSupply better goods and info

Economic Added value tax exceptions

Regulatory Information standards

SocialVoluntary initiatives for subscription schemes for organic food

Other policy influences Media policies

RETAILERSProvide facilities for recycling &repair services

Economic Local subsidies

Regulatory N/A

SocialPromotional events such as local “recycling” weeks

Other policy influences National labour cost policies



POLICY INSTRUMENT

EXAMPLE

PUBLIC AUTHORITIES

Green procurement (The selection by an organization of products and services that have reducedenvironmental impacts.)

EconomicTemporary economic incentives for “buying green”

Regulatory Procurement standards

Social Awareness campaigns

Other policy influencesInternational harmonisation and competition policies

PUBLIC AUTHORITIES

Supply better infrastructure and information

EconomicBudget grants for innovative projects

RegulatoryEnvironmental standards for use of materials

Social Consumer lobbying

Other policy influences General budget policies

NGO’S, RESEARCHERS

Information and advice, lobbying, research

Economic Subsistence subsidies

Regulatory N/A

Social Research pioneers networks

Other policy influences Curricula development



Producers can choose to: supply the same products with less environmental damage

incorporated (by means of process oriented measures such as good house keeping, pollution control, waste management);

supply improved and more eco-efficient products (eco-design, eco-labelling activities);

supply new (combinations of) products and services, satisfying underlying needs and eco-efficiency (demand-driven innovation). This includes two categories:1. Supplying services directly aimed at reducing the environmental

impact (for instance recycling services, deposit/refund schemes); and2. supplying new services that meet the need that the product fulfilled

but using less material and generating more added value to the company (a strategy that is not necessarily only provoked by the environmental agenda).


Hunger Horn of Africa

Nearly 16 million people in the Horn of Africa are threatened with starvation, according to the United Nations. Over the past two years drought has scorched crops and killed livestock across the region.

And while drought is the primary cause of the food crisis, the UN says conflict and insecurity have exacerbated the situation.


Hunger Horn of AfricaEthiopia Scores of children in Ethiopia have

already diedThe food shortages are most severe in Ethiopia, where more than eight million are at risk of famine.

The country is in the middle of a protracted war with neighbouring Eritrea, which is severely complicating relief efforts.

There is also instability in the south-east of the country, with frequent reports of banditry and rebel incursions from Somalia and Sudan. Some international aid agencies have pulled their workers out because of the danger.



Eritrea Some 367,000 people are threatened by drought and food

shortages in Eritrea.Djibouti Drought is affecting an estimated 100,000 people in this tiny

country, which is highly dependent on imported food and foreign aid.

Kenya In northern Kenya nearly 2.7 million people are facing severe

food shortages, making it the second most severely hit country after Ethiopia.

Somalia Crop failure and fighting between rival militias have left between

1.2 and 1.5 million people at risk in Somalia. Food stocks are being sent to the country in anticipation of a major emergency.



Sudan The UN estimates that 1.7m people in Sudan will need food aid this

year, with 75,000 of them at immediate risk.Uganda Drought and crop failure in north-east Uganda has caused severe food

shortages for an estimated 220,000 people.Further south The UN Food and Agriculture organisation has warned that the food

crisis could spread south to central Africa's great lakes region, where conflict, large population movements and erratic weather have created another food shortage.

The situation is particularly grave for nearly 800,000 people living in camps for displaced people in Burundi.

They are mainly Hutu peasant farmers, who are now unable to gather in their crops.

And in Tanzania, drought has affected an estimated 1m people.


The central questions

Can we sustain this level of consumption or are we degrading the Earth’s ability to support even this current level of consumption? It is estimated that humanity uses one-third more

resources than nature can sustainably replenish. By this measure, the world is already overpopulated. The estimate is that 2 to 3 billion humans could be supported sustainably at the level of consumption of Americans.


The central questions

How much will we consume fifty years from now when our population reaches 9 billion?


How many people can the Earth support? The answer to how many people can the Earth

support depends on the lifestyle we choose, and answer to the question, what do we want?

Do we want as many people as possible on the Earth at one time?

Or do we want a sustainable world where, over the history of humanity’s tenure on Earth, the greatest number of lives could be lived?

Do we want a certain level of quality to our lives? And if so, what increases the quality of our lives?


How many people can the Earth support? The answer to the carrying capacity debate is dependent

upon the choices we make about our personal reproduction, our lifestyles and consumption, and our political, economic, and social priorities.

As Paul and Anne Ehrlich noted in The Stork and the Plow: “Earth can support a larger population of cooperative, far-sighted, vegetarian pacifist saints than of competitive, myopic, meat-eating, war-making typical human beings.

All else being equal, Earth can hold more people if they have relatively equal access to the requisites of a decent life than if the few are able to monopolize resources and the many must largely do without.

The problems of population, social and economic inequity, and environmental deterioration are thus completely intertwined.”

http://www.unep-wcmc.org/

how many people can the earth support?

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