6-4 charting a course for the futuretaubitz.weebly.com/uploads/1/0/4/9/10498079/chapter06...surface,...

of 30

Copyright Pearson Prentice Hall

6-4 Charting a Course

for the Future

6-4 Charting a Course for the Future

Slide

2 of 30


6-4 Charting a Course

for the Future

Researchers are gathering data to monitor and evaluate the effects of human activities on important systems in the biosphere. Two of these systems are:

• the ozone layer high in the atmosphere

• the global climate system


Slide

3 of 30


Ozone Depletion

Ozone Depletion

Between 20 and 50 kilometers above Earth's

surface, the atmosphere contains a relatively high

concentration of ozone gas. This layer of the

atmosphere is called the ozone layer.

The ozone layer absorbs a good deal of harmful

ultraviolet, or UV, radiation from sunlight before it

reaches Earth's surface.


Slide

4 of 30


Ozone Depletion

Exposure to UV can:

• cause cancer

• damage eyes

• decrease organisms' resistance to disease

• damage plant leaf tissue and phytoplankton in the

oceans


Slide

5 of 30


Ozone Depletion

Early Evidence

In the 1970s, scientists discovered a hole in the

ozone layer over Antarctica.

After it was first discovered, the ozone hole grew

larger.

A similar ozone hole also appeared over the Arctic.

In 1974, a research team published data showing

that gases called chlorofluorocarbons, or CFCs,

could damage the ozone layer.


Slide

6 of 30


Ozone Depletion

One Solution

CFCs were once widely used:

• as propellants in aerosol cans

• as coolant in refrigerators, freezers, and air

conditioners

• in the production of plastic foams

The U.S. and other nations began reducing the use of

CFCs in 1987, and eventually banned them.


Slide

7 of 30


Ozone Depletion

Since the ban, the level of CFCs in the atmosphere

has decreased, indicating that the ban will have

positive, long-term effects on the global environment.

Current data predict that the ozone holes should

shrink and disappear within 50 years.

Global Climate Change

All life on Earth depends on climate conditions

such as temperature and rainfall.

Many ecologists are concerned about strong

evidence that climate is changing.


Slide

8 of 30



Since the late 19th century, average temperatures

have risen about 0.6 Celsius degrees.

Data indicate that since 1980, average temperatures

have risen between 0.2 and 0.3 Celsius degrees.

The term used to describe the increase in the

average temperature of the biosphere is global

warming.

One sign of global warming is melting polar ice.


Slide

9 of 30




Slide

10 of 30



Evidence of Global Warming

The geological record shows that Earth’s climate

has changed repeatedly during its history.

Researchers must determine whether the current

warming trend is part of a larger, natural cycle of

climate change, or whether it is caused by human

activity.


Slide

11 of 30



A widely accepted hypothesis is that current warming

is related, in part, to human activities that add carbon

dioxide and other greenhouse gases to the

atmosphere.

The burning of fossil fuels, along with the cutting and

burning of forests, adds carbon dioxide to the

atmosphere faster than the carbon cycle removes it.


Slide

12 of 30



Data show that concentrations of carbon dioxide in

the atmosphere have been rising for 200 years.

As a result, the atmosphere’s natural greenhouse

effect is intensified, causing the atmosphere to retain

more heat.


Slide

13 of 30



Possible Effects of Global Warming

Most recent computer models suggest that

average global surface temperatures will increase

by 1 to 2 Celsius degrees by the year 2050.

Sea levels may rise enough to flood coastal areas,

affecting coastal ecosystems as well as human

communities.

Parts of North America may experience more

droughts during the summer growing season.


Slide

14 of 30



New organisms may be able to live in places where

they once could not.

Other organisms may become threatened or extinct

in areas where they once thrived.

The Value of a Healthy Biosphere

Ecosystems provide many goods and

services, such as water purification and

waste recycling.

Ecosystems are also a reservoir of

organisms that may one day provide

humans with new medicines and new crops.


Slide

15 of 30


The Value of a Healthy

Biosphere


Slide

16 of 30



Biosphere


Slide

17 of 30



Biosphere

People can make wise choices in the use and conservation of resources.

• Avoid using more water than necessary.

• Plant trees to replace those that have been cut down.

• Recycle and reuse trash and other wastes.

• Safely remove hazardous materials.

- or -

Continue to: Click to Launch:

Slide

18 of 30


6-4

Resources/ch06_sectn04_quiz.qtb





of 30


6-4

An increase in the average temperature of the

biosphere is called

a. the greenhouse effect.

b. global warming.

c. ozone depletion.

d. climate control.

of 30


6-4

The geological record indicates that Earth’s

climate has

a. remained essentially the same throughout

history.

b. been constant until humans have influenced

the environment.

c. changed dramatically every 150 years.

d. repeatedly changed over its history.

of 30


6-4

A possible effect of global warming is

a. extinction of organisms in areas where they

once thrived.

b. an increase in global surface temperature of

20 Celsius degrees.

c. a sharp decrease in the temperature of the

waters off the coast of California.

d. complete elimination of the protective ozone

layer in the atmosphere.

of 30


6-4

Depletion of Earth’s protective ozone layer

results in

a. a decrease in the amount of heat that

reaches the surface.

b. a decrease in the amount of UV radiation

that reaches the surface.

c. an increase in the amount of rainfall.

d. an increase in the amount of UV radiation

that reaches the surface.

of 30


6-4

The most likely cause of ozone depletion is the

a. addition of carbon dioxide to the atmosphere.

b. increase in UV radiation from the sun.

c. addition of chemicals developed for use in refrigeration and aerosol cans.

d. increase in the amount of smog produced by automobiles.

6-4 charting a course for the futuretaubitz.weebly.com/uploads/1/0/4/9/10498079/chapter06...surface,...

Documents