SNCD0 – Climate Change. Components of our Climate System Earths climate system is composed of four major parts that interact with one another Atmosphere.

The Global Climate System and The

Greenhouse Effect

SNCD0 – Climate Change

Components of our Climate SystemEarth’s climate system is composed of four major

parts that interact with one anotherAtmosphere

AirHydrosphere

WaterLithosphere

LandLiving Organisms

AtmosphereThe atmosphere is a layer of gases

surrounding the planetThese gases reach more than 100 km above

Earth’s surfaceAfter this height the gases are very diffuse,

and eventually there are no gases at all (more than 600 km)

Atmospheric LayersTroposphereStratosphereMesosphereThermosphereExosphere

Atmospheric ContentsThe atmosphere contains several gases

~78% nitrogen~21% oxygen~1% is made of several gases: argon, carbon dioxide,

water, ozone (O3), helium, hydrogen, methane, etc...

The proportions of gases are slightly different at different altitudes

Ozone LayerIn the stratosphere, there is a high ozone content

This ozone is very efficient at absorbing UV radiationThe ozone layer protects us from UV lightUV light can cause cancer and can damage living

organisms

Our ozone layer has sustained damage and is now much thinner than it was a century agoAreas over the Arctic and the Antarctic have very thin

ozone layers

This damage has been shown to be from the use of chlorofluorocarbons

Ozone LayerThe blue regions show areas where the ozone layer is

thin

ChlorofluorocarbonsCFCs are carbon based molecules containing fluorine

and chlorine bonded to the carbon

CFCs have been used for several things in the past;RefrigerantDry-cleaning solutionIn Spray cansIn air-conditioners

C F

Cl

Cl

Cl

ChlorofluorocarbonsCFCs break down when reacted with UV light

The free chlorine atoms react with ozone

The chlorine atoms get recreated and are able to go and react with more ozone!Because of this, small quantities of CFCs can continually

destroy large portions of the ozone layer, and take decades to leave the atmosphere

UV →𝐶𝐹𝐶𝑙2(𝑔)+𝐶𝑙(𝑔)

Very Reactive!!

Montreal ProtocolIn 1987, governments around the world agreed to

halt all use and production of CFCs for several usesCertain CFCs are still used, but significantly less

The ozone layer should rebuild itself over timeIt is estimated to take another 50 years to get back to

normal

HydrosphereIncludes all water on Earth

Lakes, Oceans, water vapour, and ice

Water absorbs sunlight and heats up the air around itIt takes longer to heat up and cool down than landThis allows it to keep the temperature of surrounding

areas moderateAlso adds to the precipitation in surrounding areas

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IceIce is very reflective

This is part of the reason why the poles are so cold

2% of the Earths water is frozen

Increasing the temperature of the Earth causes more ice to meltWhich worsens the problem of global warming

LithosphereThe Earth’s crust

Includes solid rock, soil, and mineralsOn land and below oceans

Land formations have a large effect on temperature

AltitudeAs altitude increases, the air pressure and temperature

drops

Mountain EffectAs warm, humid air rises

up it cools

The cool air forms clouds, and eventually precipitation

This leaves cool, dry air moving overtop of the mountain

This is the reason why the prairies are so dry

Living ThingsLiving things excrete gases into the atmosphere and

change its compositionCarbon dioxide, methane, oxygen

Carbon dioxide and methane are “heat sinks”This means they are really good at absorbing light and

trapping it in the atmosphere as heatThey contribute greatly to the “greenhouse effect”

Greenhouse EffectGases in the atmosphere absorb light from the sun

They can also absorb light that is reflected from the surface of the EarthThis light is absorbed, heating up the airIt can be re-emitted by the gases in the atmosphere and

spread throughout the atmosphere

This effectively traps heat in the atmosphere for a long period before it is lost to space as infrared radiation

Greenhouse GasesCarbon dioxide

~ 0.0385% of the atmosphereCauses ~25% of the natural greenhouse effect on Earth

Carbon dioxide is released into the atmosphere naturallyCellular respirationForest firesDecomposition of previously living organisms

Carbon dioxide is also released through human activitiesCombustion of fossil fuels and garbage

Carbon SinksThere are several things that trap carbon

And thus remove carbon dioxide from the atmosphereThey are called carbon sinks

Carbon sinksPlants – photosynthesisLiving organisms – mainly composed of carbonMarine life – Shells Rocks and sediment

Losing carbon sinks increases the amount of CO2 in the atmosphere

Water VapourWater vapour accounts for ~ 66% of the greenhouse

effect on Earth

The amount of water vapour in the atmosphere depends on the temperature of the airRanges from trace amounts (less than 0.1%) to 4% of air

Warm air holds more water vapour than cold air

This generates a feedback loopA process where the result influences the original

process

Water Vapour Feedback Loop

Warm air holds more water

Water vapour retains heat, and heats up the air

This is a positive feedback loop, where the result of the process increases the effect

MethaneMethane (CH4) is about 23 times better at retaining

heat than carbon dioxideBut there is very little in the atmosphere

The concentration of methane has steadily increased since the industrial agePre-industry = 0.7 ppm (0.7 molecules in every million air

particles)Modern day = 1.785 ppm (~ 1.8 molecule in every

million air particles)It has more than doubled!

Methane is produced in plant decomposition and through animal digestion

Ozone and Nitrous OxideOzone O3

Found in the stratosphere mainlyCan be formed in the troposphere when car emissions

react with UV light producing smog (ozone one part of smog)

Nitrous Oxide N2OAlmost 300 times as effective as carbon dioxide at

retaining heatVery little in the atmosphereProduced by bacteria in soil and water and also in

combustionPre-industry = 270 ppbModern-day = 321 ppb

How do Gases trap Infrared Radiation?When molecules absorb light it causes the atoms to

vibrate back and forthThus heating them up

The more atoms, the more energy can be absorbed

Vibration Videos

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Homework

Climate System pg 335 #1 – 7

Greenhouse Effect pg 342 #1 – 7