14.3 & 14.4 Notes

14.3 & 14.4 Notes

Climate Changes & Human Factors

Main Idea 1:

Earth’s early atmosphere was far differentthan it is today!

Early Atmosphere Conditions

• Describe origin of Earth’s early gases: -Hydrogen & Helium dominated!!-Volcanoes produced CO2 & H2O.-Methane & Ammonia formed from early chemical reactions.

Changes caused by Bacteria

Explain: Ancient Cyanobacteria photosynthesized to produce Oxygen & Ozone.

O2 helped animals to respire.

03 helped protect Earth against solar UV radiation.

Evidence: Fossil records from Australian rocks.

Main Idea #2

Changes in oceanic & atmospheric currentscan have drastic effects on weather.

Normal ConditionsWestern Pacific: Typically very warm, rainy due to Easterly Trade Winds that bring warmth & push ocean waters westerly.

• Pressure: LOWER

Normal Conditions

Eastern Pacific: Air is cooler b/c winds blow away the warmth; also upwelling of cool, nutrient-rich ocean water.

Pressure: HIGH

• Diagram:

El “Warmo” Nino/Southern Oscillation

Define: The wind-driven movement of warm waterin the Pacific shifts “backwards”; causes extreme global weather disruptions .

Changes in Pacific Pressure: W. Pacific get high pressure, & E. Pacific gets low pressure (just opposite of “normal”).

El Nino/Southern Oscillation

Effects on trade winds: They get weakened & blow backwards, from W to E.

Weather effects: E. Pacific gets WARMER & rainier, & it loses its upwelling of rich nutrients (CRASHES THE FISHERIES!!).

W. Pacific gets cooler & drier.

El nino/Southern Oscillation

Cycle duration: Every 3-7 yrs; last about 1.5 yrs.

Diagram:

La “Dramatic” Nina

Describe: Pressure & trade winds reverse DRAMATICALLY

Upwelling in Eastern Pacific: GETS way too COLD!

Western Pacific Conditions: Gets WETTER than normal!

Eastern Pacific Conditions: GETs DRIER than normal!!

Cycle duration: 9-12 months.

NOAA National Oceanic& Atmospheric Administration

Measures: Water temp, currents, wind speeds

Tools Include: Satellites, drifting buoys, moored buoys, ROV’s

Main Idea #3: Climate changes naturally over time, but some evidence suggests that human activities may be augmentingthese changes.

Define: The ozone layer is a belt of naturally occurring ozone (O3) gas that is 9-19 miles above Earth. Itacts as a shield from harmful UV-B radiation from the sun.

Uses for Humans: We use CFC’s in air conditioning, old refrigerators, & solvents as some examples.

Ozone depletion(caused by CFC’s)

Atmospheric effects:

The chlorine from the CFCWill react with the ozone,And causes it to breakDown into Cl-O and O2.

This reduces the “shieldEffect”

Human effects: Humans contribute to ozonedepletion by using things that emit CFC’s.

These CFC’s inadvertently cause moreUV-B radiation resulting in humans being afflicted by skin damage; ie skin aging & cancer.

Air Pollution:

Common causes: Cars, factories, burningOf farmland for example. And all of theseGive off CO2 & other “harmful” gases.

Greenhouse Effect (caused by Carbon Dioxide):

Describe: The atmosphere close to Earth naturally contains CO2. This “blanket” of CO2causes heat that is reflected off Earth’s surfacesto bounce (reflect back) down to Earth.

As humans use more cars, burn fires, etc.. Theseactivities increase the amount of CO2, thus moreheat can get “trapped” near Earth.