Humans and the Biosphere

Hawaii• Story of Hawaii in 1600 and the self –sufficient

Polynesians• New settlers of 1700s changed the landscape even

farther • Hawaii is very different from the islands the

Polynesians settled

I. Earth as an Island• A. In a sense we must think of Earth as an island just

like Hawaii– 1. All living organisms share limited resources that affect

our long-term survival

• B. In order to protect these much need resources we need to understand not only the natural ecological processes that sustain these materials but how we affect them as well

II. Human Activities• A. Like all organisms humans participate in food

webs and chemical cycles• B. We depend on Ecological life-support– 1. For drinkable water, breathable air, fertile soil, and

storage/recycling of nutrients• B. Ecologists call these necessities “ecosystem

goods and services” since they have so much value to us

• C. We need to be aware that human activities are changing local & global environments

II. Human Activities

• D. Among human activities that affect the biosphere are – 1. Hunting and gathering– 2. Agriculture – 3. Industry– 4. Urban development.

• E. Humans have become the most important source of environmental change on the planet

III. Hunting & Gathering

• A. For most of Human history, our ancestors obtained food by hunting & gathering– 1. Even though they made relatively few demands on

the environment, scientists hypothesize that early humans changed the N. American environment greatly causing mass extinction

• B. Today groups are found throughout the world and still follow the hunter-gather way. – Most of them use some form of technology today

IV. Agriculture

• A. Began about 11,000 years ago after the Ice age.– 1. Gave humans a dependable food supply that could

be produced in large quantities and stored – 2. Allowed the growth of stable communities– 3. Practiced monoculture – planted only one crop year

to year– 4. Flourished after the invention of harvesting tools

(green revolution)

V. Industrial Growth & Urban Development

• A. Industrial Revolution in the 1800s added machines & factories to our biosphere– 1. Provides us with the convenience of todays modern

life• B. Growth of Suburbs and Urban centers

increased standard of living• C. With all these new machines, we needed an

energy source– 1. Fossil fuels (coal, oil, natural gas) provided this

energy

VI. Controlling Effects of Human Activities

Tragedy of the Commons

Scientists worry about any resource that is “free”

VI. Controlling Effects of Human Activities

• A. Use of different resources:– 1. Renewable resource – can regenerate if they are alive

and can be replenished by biogeochemical cycles if they are non living (not unlimited)• Ex: trees, fresh water

– 2. Nonrenewable resource – cannot be replenished by natural processes• Ex: fossil fuels

VII. Charting a Course for the Future

• A. Researchers are gathering data to monitor and evaluate the effects of human activities on important systems in the biosphere

• B. 2 systems they are concentrating on now are the – Ozone Layer– Global Climate System