1. Human Impact on Ecosystems
Chapter 16

2. 16.1 Human Population Growth and Natural Resources

3. A. Earth’s human population continues to grow.
1. Earth’s carrying capacity
How many people can Earth support??
Recall that carrying capacity is the maximum population size an environment can constantly support.
Thomas Malthus wrote an essay in the 1700s claiming the human population was growing faster than Earth’s resources could support.
In Malthus’s lifetime the human population was around 1 billion.

4. Today the human population is more than 6 billion.
It took all of human history to reach 1 billion, a little over a 100 years to reach 2 billion, only 30 years to reach 3 billion, an d 15 years to reach 4 billion
What is the limit?

5. 2. Technology and human population
Recall that carrying capacity can change as a result of the environment.
Humans have modified their environment through agriculture, transportation, medical advances and sanitation.
The carrying capacity of Earth has increased.

6. B. Pressures on Earth’s Natural Resources
There are two types of natural resources:
Nonrenewable- resources are used up faster than they can form
(example- oil and coal)
Renewable- resources that cannot be used up. These resources renew themselves over time
(example solar and wind energy)

7. Nonrenewable Resources
Two resources, oil and coal currently support the majority of our countries energy use.
It takes MILLIONS of years for the natural process of transforming dead organic matter into the concentrated carbon substance we use today
In 2006, the human population was using oil at a rate of 77 million barrels per day!!

8. Renewable Resources
Renewable resources can become nonrenewable if they are not used carefully..
A good example is drinking water. Because of pollution and overuse, our fresh water supplies are threatened.
Groundwater is also being extracted from aquifers faster than it is being replaced

9. The United States uses more resources and produces more waste than any other country on Earth.
Each year, The U.S. generates about 230 million tons of garbage. (4.2 pounds per day, per person- or almost a ton a year per person!)

11. C. Managing Earth's Resources
Management of Earth's resources affect both current and future generations….

12. Ecological Footprint
The amount of land necessary to produce and maintain enough food and water, shelter, energy and waste is known as an ecological footprint
The size of an ecological footprint depends on:
The amount and efficiency of resource use
The amount and toxicity of waste produced

14. 16.2 Air Quality

15. Fossil fuels Fossil fuels are important part of our world
Ancient organisms absorbed the sun’s energy and stored this energy in their biomass
Today, humans burn these fuels in the form of gas and oil
This in turn pollutes our atmosphere

16. A. Pollutants Accumulate
Each year humans add synthetic chemicals and materials to the Earth
Many of these can not be integrated into normal ecosystem functions
Pollution describes any desirable factor, or pollutant, that is added to the air, water or soil

17. Pollution can take the form of microscopic air particles or waste products from factories and sewers, or household chemicals that are pored down the sink!
The harmful effects from pollution can be immediate or delayed, and they may ADD UP over time

18. Smog and Ozone Most common Comes from burning fossil fuels
Smog is a type of air pollution that comes from the interaction of sunlight and pollutants produced from fossil fuel emissions
Components of smog include particulates (microscopic bits of dust, metal, and unburned fuel) and ground level ozone

20. Acid Rain
Burning fossil fuel creates nitrogen oxides and sulfur oxides which in turn create acid rain (pH > 7)
Acid rain in turn decreases the pH of lakes and streams and threatens our water supply and species habitat
Acid rain can also cause growth rate to decline and cause trees to become more at risk for disease

22. B. Air Pollution and Biosphere
Our atmosphere naturally includes molecules of CO2 that help keep the biosphere at a temperature to support life
The levels of CO2 naturally rise and fall.
Higher levels of CO2 are typically in warmer periods, lower levels are associated with cooler climates

24. 1. Greenhouse effect

25. Global Warming
Over the past 100 years the average temperatures have risen 0.6 °C ( 1.2 °F)
Increased levels of greenhouse gases have caused this change (CO2, water vapor and methane)
Ecological disasters such as increased flooding, stronger tropical storms, and loss of biodiversity are a few threats that may be caused by global warming
Polar ice caps are melting
By 2100 scientists estimate temps to increase
2.2 – 10 °F

27. 16.3 Water Pollution

28. A. Effects on Ecosystems
Pollution has a major impact on water ecosystems
Raw sewage, trash, chemical pollutants etc. end up in our rivers, aquifers all over the word
One way scientists determine the health of an ecosystem is through indicator species (bioindicator)
Indicator species provide a sign of the quality of an ecosystem’s environmental condition.
Frogs and tadpoles are often used because their skin can be permeated by water- thus extra arms and legs can indicate direct contact with pollution

31. B. Biomagnification
Occurs when fat soluble pollutants move from one organism to another up the food chain accumulating in higher concentrations in the bodies of predators
Measured in ppb
Pesticides are a good example