Pg. 70What is climate? - The general atmosphere conditions

of a country or region.a.) temperatureb.) windsc.) moistured.) duration of seasons

What creates climate?1) amount of solar radiation (insolation) received and/or retained on planet Earth.

Remember the weather unit?

Pg. 70HOW CAN SOLAR RADIATION BE AFFECTED1.) Volcanic Activity - Ben Franklin realized could affect

weather (1784)!

a.) Ash and dust block sun

b.) Gas sulfur dioxide reacts to form sulfuric acid in atmosphere block sun OR CO2 can….

ADD c.) Paradox/conundrum Add to Greenhousegases/effect. Is it possible that volcanic activity canhave two effects?

Three biggie eruptions:Tambora 1815, El Chichon 1982, Mt. Pinatubo 1991

Pg. 70HOW CAN SOLAR RADIATION BE AFFECTED(CONTINUED)

2) Impact – dust and debris block incoming sunenergy (insolation)

Pg. 70HOW CAN SOLAR RADIATION BE AFFECTED(CONTINUED)

3) Orbital Variations - Milankovitch SUPPLEMENTAL

How much solar radiation reaches earthand at what lat. and seasona) Eccentricity -changing from circular to

more elliptical

1.) more elliptical=less insolation

2.) 100,000 year cycle: which seems to match glacial advance and retreat times based on oxygen isotope record in the ice sheets.

Pg. 70HOW CAN SOLAR RADIATION BE AFFECTED(CONTINUED)

3) Orbital Variations – Milankovitch SUPPLEMENTAL

b) Tilt- varies from 21.5 to 24.5 degrees1.) 41,000 year cycle.2.) during great tilt angles increased

seasonal extremes. This would include greater snow

melt=less ice3.) Lower tilt=warmer winter=more

precip. to form more snow/ice. BUT the summer would be cooler when most melting would occur.

Pg. 70HOW CAN SOLAR RADIATION BE AFFECTED(CONTINUED)

3) Orbital Variations – Milankovitch SUPPLEMENTALc) Wobble (Precession)- spinning top analogy: tilt is the same but it wobbles.19,000-23,000 year cycle.

1.) Currently the wobble has Earth closer to sun during winter=mild winter compared to southern hemisphere

2.) If pointing away (winter) while a long ways away super cold then pointing toward (summer) while close. BIG seasonal contrast. Conundrum?

ADD SUMMARY

Like precession, axial tilt could cause warmer winters, thatrelate to more moisture available (more snowfall), and cooler summers, more snow/ice lasts through the summer months.

Pg. 70HOW CAN SOLAR RADIATION BE AFFECTED(CONTINUED)

BUT WAIT!!!!!!! Milankovitch problems?

These orbital variations seem to effect the hemispheres differently (sometimes at least). So…….

The idea is that if there is more heat in the system (Earth) the oceans and atmosphere will distribute this for a net increase in temps. on Earth.

This theory is highly substantiated by oxygen isotope record.

Pg. 70-71HOW CAN SOLAR RADIATION BE AFFECTED(CONTINUED)

4)Ocean/atmosphere system - Generally warm watermoves to poles and cold water to EQ

a.) Tectonics affect by moving continents

b.) Ocean currents (thermohyline conveyor) can also change by changing salinity of water (St. Lawrence)

DRAWING FOR ST. LAWRENCE EXAMPLERESULTS???

El Nino (short term change)= warm water makes it to coast of Peru and Ecuador kills fish creates lots of rainfall which results in flooding and mass wasting

Pg. 71HOW CAN SOLAR RADIATION BE AFFECTED(CONTINUED)

5) GREEN HOUSE - HUMAN AFFECTIncoming sunlight is short wavelength (UV) and CANpenetrate the atmosphere. Earth’s surface emitslong wavelength energy (infrared) and CANNOT penetrate the atmosphere.

Pg. 71HOW CAN SOLAR RADIATION BE AFFECTED(CONTINUED)

5) GREEN HOUSE Greenhouse Gases (continued)Carbon Dioxide -the biggie. Methane - cows and swamp gas (organic

decay)melting of methane hydrates on ocean

floor?Ozone - forms in upper atmosphere.

3 oxygens hooked together. Absorb long wavelength.

Nitrous Oxide – agriculture-fertilizers and fossil

fuel combustion

Pg. 71HOW CAN SOLAR RADIATION BE AFFECTED(CONTINUED)

LET’S FOCUS ON CARBON DIOXIDE

SINKS – where CO2 is stored

Organic material: lots stored in permafrostRocks: Coal and limestoneOcean: Water and sediments

Pg. 71HOW CAN SOLAR RADIATION BE AFFECTED(CONTINUED)

LET’S FOCUS ON CARBON DIOXIDESOURCES

Volcanoes, ocean water and organicsBurning Fossil fuels significant source Weathering of Limestone

Other organics: warm up permafrost = melting=increase in decomposition of organics=release of carbon dioxide and methane RESEARCH LINK ON PERMAFROST AND CARBON SEQUESTERINGCreates positive feedbackCARBON CYCLE LINK

Pg. 72

**Today we produce an unnatural abundance of CO2 andmethane by burning fossil fuels and weathering(increasing temps increases weathering rates)of limestone

ADDIsn’t this part of the carbon cycle?The problem is what???

And that leads to….

Add more to atmosphere THAN CAN BE TAKEN OUT BYNATURAL PROCESSES and will let solar radiation inbut not out!=warming

Pg. 72IS GLOBAL WARMING REAL???

MANY SAY YES Some say No WE CAN MEASURE IT- are measurements accurate

and representative???

a.) Earth’s average surface temperature > 1 degree F in past 100 years But….ND pg. 295 Fig. 10.39

b.) Models suggest an increase in warming in past 20 years is attributed to human activities

Pg. 72IS GLOBAL WARMING REAL???

MANY SAY YES Some say No CONTINUED

c.) In the 20th century the 10 warmest years

were between 1985-2000! But….

d.) Since industrial revolution 30%> ingreenhouse gases

ADD CALCULATIONS/MODELS1.) Suggest human activity caused a +0.4C global temp. change

2.) Only a small increase in greenhouse gases could “tip the scales” toward disaster. Why beg the issue?

Pg. 73HAS THE EARTH WARMED AND COOLED IN THE PAST??YES - HOW DO WE KNOW???Use the geologic record stored in rocks, sediment,

fossils, and topography

1)Topography = shorelines record changes in sea level

a.) lake shorelines record changes in climate patternsb.) Dune fields in Nebraska now stabilizedc.) Glacial topography and evidence in areas where none

exist today (NY and Midwest)

Pg. 73HOW DO WE KNOW??? continued2) Sediment = ocean sediment record change (fossils)

a.) Lake and bog sediment record vegetationchanges (pollen).

b.) Gives a pretty detailed account ofclimatic changes

c.) plants are sensitive to climatic change BUT remember they are robust in terms of extinction

Pg. 73HOW DO WE KNOW??? continued

3)Fossils - cool weather fossils found in warmedlocation etc. dinos in Arctic

Pg. 73HOW DO WE KNOW??? continued4) Rocks - Tell story of changes in the past

a.) Tillite and Coal very important

b.) Limestone and reefs

c.) Halite and Gypsum

ADD EACH ARE EVIDENCE OF WHAT???? LOCAL EXAMPLESa.) ?????

b.) ?????

c.) ?????

Pg. 73HOW DO WE KNOW??? continued

5)Last 1,000 years historic records provide a uniquelook at past climate

1) grain and grape crops (tax records)2) advance and retreat of mountain glaciers in Europe 3) paintings – frozen canals etc.4) sea ice records from around Iceland

ADD HOW COULD EACH OF THE ABOVE HELP???1.)2.)3.)4.)

Pg. 74From 1000 - 1300

a.) Medieval Maximum (Optimum) -times are goodand warm.

b.) Iceland and Greenland were settled (farming)

Pg. 74From 1400-1900

a.) Little Ice Age

b.) Cold in Europe – reduced crops = famine

c.) Iceland and Greenland abandoned

d.) Canada had build up of snow fields and thebeginnings of icesheets

Pg. 74From 1645-1715

a.) Maunder Minimum – especially cold!b.) Usually attributed to decreased sunspot

activity.