Earth as an Island

¨       Earth is similar to as island because all the organisms that live on Earth share a limited resource base and depend on it for their long-term survival.

Human Activities

¨       Humans participate in food webs and chemical cycles which provide breathable air, drinkable water, and fertile soil.

¨       Ecosystem processes provide us with “services” such as storage and recycling of nutrients.

¨       If we don’t get these “goods and services” from the environment, we will need to spend money to produce them

¨       The human activities that affect the biosphere are:

Ø       Hunting and gathering

Ø       Agriculture

Ø       Industry

Ø       Urban development

Hunting and Gathering

¨       Our ancestors obtained food by hunting and gathering.

¨       This practice caused a mass extinction of animals in North America about 12,000 years ago.

¨       Today, groups of people scattered around the world still follow the hunter-gatherer way of life to some degree.

¨       Most of them use some form of technology, such as guns, snowmobiles, or manufactured tools.

Agriculture

¨       By the end of the last ice age-about 11,000 years ago, humans began the practice of farming, or agriculture.

¨       The development of agriculture also included raising animals.

¨       The spread of agriculture was among the most important developments in human history.

¨       It provides a dependable supply of food that can be produced in large quantity and stored for later use.

¨       This lead to large settlements and stable communities.

From Traditional to Modern Agriculture

¨       Farmers eventually acquired machinery to help with cultivation.

¨       World exploration led to an exchange of crops around the globe.

¨       Advances in technology also lead to large scale irrigation in dry areas such as the western United States allowing deserts to become breadbaskets.

¨       Agricultural scientists developed new varieties of crops that produce higher yields.

¨       These crops were grown using monoculture in which large fields are planted with a single variety year after year.

¨       Chemical fertilizers boosted plant growth and pesticides controlled crop-damaging insects.

The Green Revolution

¨       The green revolution greatly increased the world’s food supply.

¨       Plant breeder’s developed highly productive “miracle strains” of wheat and rice.

¨       Modern techniques were also introduced to countries that were suffering from food shortages.

v      Mexican farmers increased their wheat production ten times in 20 years.

v      India and China produced enough food to feed their own people for the first time in years.

¨       The green revolution has helped world food production double.

Challenges for the Future

¨       Modern agriculture has created ecological challenges.

Ø       Insect pests and diseases cause farmers to increase the use of pesticides which:

ü       Contaminate water supplies

ü       Damage beneficial insects

ü       Accumulate in the environment

Ø       Finding enough water for irrigation

ü       The West and Midwest depend on the Ogallala aquifer (underground water deposit).

ü       It is expected to run dry within 20 to 40 years.

¨       Ecologists conclude we need to maintain the benefits of modern agriculture while developing new approaches to protect natural resources.

Industrial Growth and Urban Development

¨       The Industrial Revolution transformed human society by adding machines and factories during the 1800’s.

¨       Mass-produced farm machinery makes efficient, large-scale agriculture possible.

¨       Automobiles give us mobility.

¨       Energy is produced from fossil fuels-coal, oil, and natural gas.

¨       Certain kinds of industrial processes pollute air, water, and soil.

¨       Dense human communities produce wastes that must be disposed of.

¨       Suburban growth consumes farmland and natural habitats placing stress on plant and animal populations.