3.7Limits to Growth

Carrying Capacity The number of people (organisms) that

can be supported by a given ecosystem, based on their consumption of natural resources.

Each species has requirements for survival and reproduction water food space shelter

REVIEW!! Label the following growth curve:

Difficult to Calculate for Humans

We use a much wider range of resources than other species

Technology changes the amount and type of resources required. (No other animals have value in uranium for nuclear power)

Humans can substitute one resource for another when the 1st resource becomes limited.

Lifestyle differences among humans mean different populations at different places and times have different needs. (Maasai tribe vs. New York banker.)

Humans have developed transportation for bringing resources in from other ecosystems, (artificially increases local carrying capacity…does not change

the global carrying capacity).

The 3 R’s

Reduce: Use fewer resources Use less paper, food, water…

Reuse: Use more than once Use water bottle multiple times

Recycle: Use objects material again to manufacture a new product Plastic bags plastic poles for gardens

Reducing Resources Activity

Activity: How would changes in the following impact human carrying capacity? Where would the reductions come from (i.e. how could we accomplish them)? ▪ energy use▪ material use▪ reuse of materials ▪ (can’t reuse energy - why?)

▪ recycling materials▪ What are the positives and Negatives of each?

3.8 Environmental Demands of Human Populations

Ecological Footprint

The area of land that would be required to provide a population with all resources and process all its wastes.

Also a quantitative estimate of carrying capacity (land area instead of population)

Calculate Eco. Footprint

Calculate your Ecological Footprint

www.footprintnetwork.org/en/index.php/GFN/page/calculators/

www.bestfootforward.com/footprintlife.htm

www.myfootprint.org/1.489 × 1010 hectares on the

Earth7.023 x 10 9 People live on EarthCalculate the hectares per capita

if everyone lived like you. 1 Hectare is about the size of a

soccer field

Per Capita Hectares

Sample Calculation of hectares per capita

Global Ecological Footprint

Who has bigger feet? MEDC vs. LEDC

MEDC : Large 2x energy in

their diet (animal products)

Higher CO2 Production

LEDC: Small Less animal

consumed = lower grain consumption

Policies that affect population growth

Economic Welfare: Improve economy and birth rates will come down on their own

Education: Promotes birth control/ economic independence of women

Domestic development: Improve sanitation, agriculture…) Decrease death rate, increase birth

Technology and Carrying Capacity

If technology increases, many argue that carrying capacity could continue to increase. If technology allows us to use

energy/material twice as efficiently, in theory the population could now double