Earth 2

Thursday, April 20, 1999
Announcements:

Lecture notes:

Stratospheric Ozone

• This is what protects us from UV.
• However, normal ozone selectively absorbs incoming UV.

CO2-Global Warming

• The only thing that we are virtually certain of is that the stratosphere will cool--this is because Cl2 formed ice crystals on polar stratospheric clouds, which cools the stratosphere down to about -80 degrees Celsius.

Tropospheric Ozone

• At the surface, ozone is a toxic irritant

• Photochemical Smog is what comes from CO & NO put up into the atmosphere in the morning then reacting with the sunlight in the afternoon.

Deforestation

• Deforestation usually occurs in areas between 5 degrees North Latitude and 5 degrees South Latitude.
• There are high rates of precipitation (up to 2000 mL) per season.
• There is lots of diversity in these areas.
• Many interdependencies between life occur here.

Nutrient Paradox

• Huge productivity.
• The surface waters have large amounts of nutrients--this is because plants are very good at recycling nutrients (b/c of their root systems and fungi)...COMPLEX ADAPTATION
• The soil has very few nutrients.
• The streams also have a very low nutrient count.

Reasons for Deforestation

1. Logging--selectively remove trees to sell to various buyers

2. Cattle--forests are cleared for cattle by burning down the trees

3. Farms--much of the deforested land is later used as farm land

Effects

1. Nutrients

• Very nutrient-poor soil leads to a high failure rate with crops

2. Regrowth is Difficult

• It is very hard for the earth to re-establish itself

3. Precipitation

• 50% of the rainfall is recycled through things like evapotranspiration

4. Erosion

• No root system is active keeping the soil in place
• This loss of soil causes more nutrients to be ripped off
• Streams also become quite turbid

5. Loss of Life

6. CO2

• The burning and combusting of organic matter produces CO2
• 8-10% of the increase in CO2 is a result of forest burning

Global Effects

1. CO2 causes an increase in global warming

2. Hadley Circulation--teleconnection

• The weakened Hadley Circulation influences the mid-latitudes causing less defined deserts and less precipitation

FORESTS...

• low albedo (.06)
• "cool"
• cause the earth to be cool b/c of evapotranspiration

NO FORESTS...

• high albedo (.20)
• "hot"