Environmental Science: Toward a Sustainable Future Richard T. Wright

The Atmosphere: Climate, Climate Change, and Ozone Depletion

PPT by Clark E. Adams

Chapter 20

El Niño: What Happened?

Jet streams shifted from normal course

Cause unknown

April May

June

The El Niño Effects: Fig. 20-1

Landslides on the California coast Mildest hurricane season in many years Rain five times normal in an East Africa

drought region Record crop harvests in India, Australia,

and Argentina

La Niña: What Happened?

Easterly trade winds reestablished with greater intensity

Upwelling of colder water from ocean depths

Jet streams are weakened Global patterns in moisture and

evaporation return to “normal”

Atmospheric Structure

Weather: Solar Energy Balance

Most solar energy absorbed by atmosphere, oceans, and land

Weather: Convection Cell

Tornadoes

Cold low-pressure air mass collides with a warm high-pressure air mass

http://www.photolib.noaa.gov/nssl/nssl0065.htm

Fujita Scale Measures the Intensity of Tornadoes F-0: 40–72 mph, chimney damage, tree

branches broken F-1: 73–112 mph, mobile homes pushed off

foundations or overturned F-2: 113–157 mph, considerable damage,

mobile homes demolished, trees uprooted

Fujita Scale Measures the Intensity of Tornadoes F-3: 158–205 mph, roofs and walls torn down,

trains overturned, cars thrown F-4: 207–260 mph, well-constructed walls

leveled F-5: 261–318 mph, homes lifted off foundation

and carried considerable distances, autos thrown as far as 100 meters

Climates in the Past

Ocean and Atmosphere

Covers 75% of the Earth’s surface Major source of water to hydrologic cycle Major source of heat to atmosphere Stores and conveys heat

The Ocean Conveyor System

The Earth as a Greenhouse

Factors Affecting Global Temperatures

Cloud cover: cooling Changes in Sun’s intensity: cooling or

warming Volcanic activity: cooling Sulfate aerosols: cooling

Atmospheric CO2 Concentrations

Global Surface Temperatures

Global Carbon Cycle

Impacts of Global Warming

Melting of polar ice caps Flooding of coastal areas Massive migrations of people

inland

Evidences of Climatic Change

17 of the hottest years on record have occurred since 1980 (Fig. 20-5)

Wide-scale recession of glaciers Sea level rising

Predicted mean global temperature changeby 2100 is between 1.5 and 4.5oC

Responses to Climate Change

Response 1: mitigation = reduce CO2 emissions

Response 2: adaptation = accepting and learning to live with the consequences of climate change

Framework Convention on Climate Change (FCC) Relied on voluntary approach to reduce

CO2 emissions Developing countries continue toward

developed nation status using fossil fuels

Framework Convention on Climate Change (FCC) To achieve a 7% reduction by 2010

requires a 25% reduction of present use By 2010 CO2 emissions will have

increased by 30%

Framework Convention on Climate Change (FCC)

Bottom line: need 60% reduction (144 ppm) in CO2 emission worldwide NOW to stabilize greenhouse gas concentrations at today’s levels

Depletion of Ozone Layer

Radiation and importance of the shield Formation and breakdown of the shield Coming to grips with ozone depletion

Good Ozone!

Bad Ozone!

Electromagnetic Spectrum

Formation of the Ozone Shield

Reaction #1: UV light + O2 O + O

Reaction #2: Free O + O2 O3

Reaction #3: Free O + O3 O2 + O2

Reaction #4: UV light + O3O + O2

Breakdown of Ozone Shield

Reaction #5: CFCl3 + UV Cl + CFCl2

Reaction #6: Cl + O3 ClO + O2

Reaction #7: ClO + ClO 2 Cl + O2

Which reaction releases Cl from CFCs?Which reaction generates more Cl?

Chlorine is a catalyst that destroys the production of ________?

Montreal Protocol

1987 – scale back CFC production by 50% by 2000

Coming to Grips with Ozone Depletion: Montreal Protocol

1990 – amendment to completely phase out ozone-destroying chemicals by 2000

1992 – amendment to completely phase out ozone-destroying chemicals by 1996

Why the rush?

Ozone Hole: 11 million sq.mi.

The Clean Air Act of 1990: Title IV

Restricts production, use, emissions, and disposal of ozone-depleting chemicals

Regulates the servicing of refrigeration and air-conditioning units

“Protecting Stratospheric Ozone”

Greenhouse Gases Ozone

Where

Type of Light

Chemicals

What’s the big deal?

Major Law

How do we fix it?

End of Chapter 20