Atmosphere and Climate Changech.13

Why You Should Care:Popular Issue – interestingAffects federal policy, global policyAcademic StudyIt is a realityCan we do something about it?

Earth and Human Systems

Global Temperatures are Increasing

http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A2.gif

Carbon Dioxide Has Increased

http://www.esrl.noaa.gov/gmd/ccgg/trends/

Global Temperature Change Over Time

http://www.scotese.com/climate.htm

What is the difference between weather and climate?

Weather – is the state of the atmosphere at a particular place at a particular time

Climate – is the long-term prevailing weather conditions at a particular place based on records taken

What Factors Determine the Climate?

LatitudeAtmospheric circulation patterns

Oceanic patternsLocal geographySolar activityVolcanic activity

1. Latitude- the distance from the equator in degrees north or south.The amount of solar energy an area of Earth receives depends on its latitude

http://www2.gi.alaska.edu/alison/SNW_09B_SolarEnergy.html

2. Atmospheric CirculationCold Air sinks because it is denser.

As it sinks it compresses and warms.

Warm air rises. It expands and cools as it rises. Warm air can hold more water vapor than cold air can.

Solar energy heats the ground warm air rises cooler air moves in to replace it

This circulation pattern determines Earth’s precipitation pattern

Atmospheric circulation driven by uneven heating of the Earth by the Sun

Atmospheric circulation driven by uneven heating of the Earth by the Sun

http://earthguide.ucsd.edu/eoc/middle_school_t/teachers/earth/sp_atmosphere/p_atmo_circulation_explanation.html

Atmospheric Circulation, cont’dPrevailing winds – blow predominantly in

one direction, not directly northward or southward (because of Earth’s rotation)

Trade winds – blow b/w 30* North and 30* South

Westerlies – produced b/w 30*-60* North and South latitudes

Polar Easterlies – blow b/w 60* to poles both North and South

3. Oceanic CirculationThe ocean currents redistribute heat on the planet.

The Gulf Stream carries warm tropical waters to the polar regions

California current carries cooler polar waters towards the tropics

Ocean Circulation

Surface Currents that changeEl Nino – Southern Oscillation. 6-18 months.Winds in the western Pacific, which are usually weak,

strengthen and push warm water eastward.Effects:1. Increased rainfall west coast of S. America and S.

eastern U.S.2. Drought in Indonesia and Australia3. http://www.esrl.noaa.gov/psd/map/clim/sst_olr/el_nin

o_anim.shtml La Nina – water in the eastern Pacific is cooler than

usual. Pacific Decadal Oscillation – 20-30 yr. change in

location of warm and cold water masses in the Pacific Ocean

4. TopographyTemperatures fall by 11* F for every 1,000

m. increase in altitudeRain shadow - Rain on West side of

Mountain – dry on East.Water cools and warms faster than landhttp://www.newton.dep.anl.gov/askasci/env

99/env99395.htm

Rain Shadow

Other Influences on Earth’s ClimateSolar maximum – the sun emits an

increased amount of UV radiation which warms the ozone more hence warming the stratosphere.

Volcanic Eruptions – Sulfur dioxide gas reacts with the smaller amounts of water vapor and dust in the stratosphere forming a bright layer of haze than reflects enough sunlight to cause global temps. to decrease

Aerosols – cool the atmosphere

Seasonal Changes in ClimateSeasons are a result of the 23.5* tilt in

Earth’s axis.Because of the tilt, the sun’s rays hit the

Earth at different angles thus heating it unevenly.

During summer in the N. Hemisphere, the N. Hemisphere tilts toward the sun and receives direct sunlight

Seasonal Changes in Climate

POP QUIZ SEC. 1answer on ¼ sheet of paper and turn in

1.List one reason you should care about climate change.

2.What is the difference between weather and climate?

#3-5 List 3 factors that determine the climate

Sec. 2 The Ozone ShieldOzone – O3

The ozone layer is in the stratosphere and absorbs

harmful UV rays from the sun.

CFC’s – chloroflourocarbons – coolant in refridgerators

and air conditioners, and propellent in spray cans.

CFC’s break apart in the stratosphere and destroy

ozone

A single chlorine atom from CFC can destroy 100,000

ozone molecules

Ozone Hole – a thinning of the ozone layer that occurs over the poles during the spring.

http://www.atmos.pku.edu.cn/yhu/ozone.html

Ozone Formationhttp://www.theozonehole.com/twenty.htmEffects of ozone thinning on humans: UV damages DNA can cause skin cancerEffects of ozone thinning on plants and

animals: kills phytoplankton – provides most of the

oxygen on earthHarms amphibian eggs – amphibians are

indicators of healthy/unhealthy ecosystemInterferes with photosynthesis of plants

Protecting the Ozone Layer1987 Montreal Protocol – nations agreed to

put limit on CFC emissions

1992 – developed countries agreed to

eliminate all CFC’s by 1995

CFC’s remain active in stratosphere for 60-

120 years

Sec.3 Global Warmingan increase in the earth's average

atmospheric temperature that causes

corresponding changes in climate and that

may result from the greenhouse effect.

Exacerbated by the greenhouse effect- the

radiation of heat given by trapped gases in

the atmosphere.

Major greenhouse gases: water vapor,

carbon dioxide, chlorofluorocarbons,

methane, and nitrous oxide.

Measuring Carbon Dioxide in the atmosphereMeasured at Mauna Loa, Hawaii Most CO2 released is 1) dissolved in the

ocean 2) absorbed by plantsCO2 increases acidity in oceans – it

combines with water to make carbonic acidLong term measurements taken from ice

cores- shows that levels today are higher than the past 420,000 years.

Effects of a Warmer EarthRising sea levels

Cycles of plants and animals changing

Tropical diseases, insects and other organisms moving

northward

Change in ocean currents causing change in weather

patterns

Heat-related deaths

Drought

Food shortages

Prevention/SolutionsScientists use computer models to predict

changes in the climateIPCC – Intergovernmental Panel on Climate

Change – a network of 2,500 of the world’s leading climatologists from 70 countries that provide information on climate change, and make predictions on climate change

Kyoto Protocol – requires developed countries to decrease emissions of carbon dioxide and other greenhouse gases by an average of 5% below what it was in 1990’s by 2012.