Global Climate Change

The Greenhouse Effect,Carbon Dioxide Emissions

&Possible Effects?

Gases of the Atmosphere• Earth’s atmosphere

consists of nitrogen (78%) and oxygen (21%) gases– Sunlight (and thus heat)

passes right through gases.

• However, other gases such as water vapor, carbon dioxide, nitrous oxide, ozone, methane, and CFCs absorb heat from the sun (greenhouse gases)

Warming Processes:The Greenhouse Effect

• A natural phenomenon that keeps Earth warm

• Without it, no life would exist on Earth (Good Thing)

• It would actually be about 33°C (60°F) colder than it is now

• Water vapor is the most abundant greenhouse gas (about 2/3)

How a Greenhouse Works?• Light passes through the glass• Some of the energy is absorbed

by the soil, plants, and glass • As the soil & plants warm they

give off heat, which is absorbed by the glass, warming the inside of the greenhouse

• The glass gives off heat (inside and outside)

• This is why greenhouses are warm when it’s cold outside

• Same principle also applies to your car

Earth’s Greenhouse Effect

Cooling Processes

• Earth has ways of cooling itself

• Albedo effect describes the amount of light reflected by the planet (Earth)– SNOW/ICE– Clouds– Water – Land

Effect of Human Activities• Other gases also absorb heat and contribute to the

greenhouse effect. Human activity can increase the amount of those gases in the atmosphere.

Human Contributions to the Greenhouse Effect

• Increased levels of carbon dioxide are due to – burning of fossil fuels (also

increases nitrous oxide levels)– slash and burn agriculture– automobiles.

• Methane comes from anaerobic breakdown of organic material in swamps, rice paddies, landfills, intestinal tracts (farts), natural gas leaks

• Chlorofluorocarbons (CFCs) come from aerosols, refrigerants, styrofoam (but is currently being phased out)

Trends in CO2 Concentration

Greenhouse Effect:

• methane (CH4)

•nitrous oxide (N2O)

Greenhouse Gases Affect on Climate

Affect of Activities on Climate

Global Warming (aka Global Climate Change) PLEASE KEEP AN OPEN MIND!!!!

• Global warming is the increase in Earth surface temperature due to an introduction of high levels of greenhouse gases because of human activities

• Global warming is NOT a good thing

YAY!!!!!• The oceans are able to

absorb a lot of the CO2 that we produce

• There are limits to what the oceans can absorb– Absorb about half

of all man made CO2

– But CO2 makes oceans more acidic

What is the Connection Between CO2 Emissions and Global Warming?

• The Earth experiences a huge range of temperature variations (hot and cold)

• We really have no idea if the changes we are observing are really due to emission of greenhouse gases by human activity.

• We have an idea about how greenhouse gases affect the temperature balance of the Earth

CO2 Emissions and Global

Temperatures

Some Ways to Reduce Greenhouse Gases

• Reduce CO2 emissions

• Charge carbon taxes/polluter pays

• Switch fuel types

• Halt deforestation

• Support reforestation

• Globally ban CFCs (we are in the process of doing this)

THE OZONE LAYER

What is Ozone?• An ozone molecule is a

temporary association of three oxygen atoms

• Energy from lightning or ultraviolet radiation from the sun breaks apart O2 molecules.

• The single atoms can combine with O2

molecules to form O3.

Ozone Layer• The ozone layer is a slight

concentration of ozone gas in the upper atmosphere (GOOD)

• It shields us from the harmful effects of the Sun’s ultraviolet (UV) radiation– Causes melanoma (skin

cancer) and cataracts.• Without the ozone layer,

life would be restricted to the oceans

Ozone in the Lower Atmosphere

• In the lower atmosphere, ozone functions as a greenhouse gas (BAD)

• It is considered poisonous, and is a component of smog. Automobile exhaust produces the majority of ozone in the lower atmosphere.

• IN THE UPPER ATMOSPHERE OZONE IS GOOD. IN THE LOWER ATMOSPHERE IT IS BAD!

Human Activities and Ozone

• Chlorofluorocarbons (CFCs) produced made their way into the upper atmosphere where it has been destroying the ozone layer

• CFCs come from refrigerators and air conditioners (freon) – there is no natural source of CFCs

• It takes 50 to 100 years for CFCs to break down.

The Hole in the Ozone Layer

• The thinning (40-70%) of the ozone layer over Antarctica

• In the Antarctic winter, the formation of icy clouds provides sites for CFCs to react and produce chlorine atoms

• These atoms then stay attached to the clouds until spring

• In spring, the ice crystals melt, releasing the Cl atoms to the air which react to remove ozone

• The Ozone Layer hole is greatest during the Antarctic spring

• STARTING TO GET SMALLER!!

The Good News!

• CFC production fell 77% between 1988 and 1995.

• Chlorine levels should be back to safe levels by 2045.

• Good example that the world can act quickly and effectively when needed.

VERY IMPORTANT!!!!!!!!!

• Even though ozone acts as a greenhouse gas in the LOWER ATMOSHPERE (BAD), the hole in the ozone layer (UPPER ATMOSPHERE) HAS NOTHING TO DO WITH GLOBAL WARMING!