global change - unit 9

Troposphere

Lowest atmospheric layer where weather occurs; temperature and pressure decrease with altitude

Stratosphere

Layer containing ozone layer; temperature increases due to UV absorption

Mesosphere

Layer above stratosphere

Thermosphere

Upper atmospheric layer with very high temperatures

Exosphere

Outermost atmospheric layer

Ozone Layer Function

Blocks about 95% of harmful UV radiation

Importance of Ozone Layer

Protects life and supports evolution on Earth

Ozone Depletion Location

Most severe above the poles

Ozone Depletion Cause

Caused mainly by CFCs

CFC Definition

Chlorofluorocarbons used in industrial applications

CFC Discovery

Discovered by Thomas Midgley Jr. in 1930

CFC Uses

Refrigerants, aerosols, cleaning agents, insulation

CFC Properties

Stable, nonreactive, odorless, nonflammable

Rowland and Molina

Scientists who linked CFCs to ozone depletion in 1974

CFC Behavior

Remain stable in troposphere and act as greenhouse gases

CFC Movement

Rise to stratosphere over time

CFC Breakdown

UV radiation breaks them releasing chlorine

Ozone Destruction

Chlorine breaks O3 into O2 and O

CFC Lifespan

65–385 years

Ozone Damage Scale

One chlorine atom destroys many ozone molecules

Reaction Step 1

Cl + O3 → ClO + O2

Reaction Step 2

ClO + O → Cl + O2

Natural Ozone Factor

Ice crystals release trapped chemicals in Antarctica

Antarctic Ozone Hole

Caused by release of ozone-depleting chemicals

UV Effects on Humans

Skin cancer, cataracts, sunburns

UV Effects on Environment

Reduced crops, forest damage, aquatic harm

Ozone Solution

Replace CFCs with alternatives

CFC Alternatives

HCFCs and HFCs

Alternative Problem

Still greenhouse gases

Other Ozone Chemicals

Halons and methyl bromide

Montreal Protocol

1987 agreement to reduce CFCs

Montreal Goal

Reduce emissions by 35%

Copenhagen Amendment

Accelerated phaseout of ODCs

Montreal Success

CFC production mostly eliminated

Greenhouse Effect

Natural warming of Earth by trapped heat

Greenhouse Importance

Keeps Earth warm enough for life

Average Temperature

About 15°C

Ocean Role

Stores heat and CO2

Cooling Processes

Evaporation and photosynthesis remove heat and CO2

Greenhouse Gases

CO2, CH4, N2O, water vapor, CFCs

CO2 GWP

1

Methane GWP

About 85

Nitrous Oxide GWP

About 265

CFC GWP

About 7000

Water Vapor Note

Short residence time so less impact

Climate Change Cause

Excess greenhouse gases

Sea Level Rise

From melting ice and expansion

Storm Impact

More severe storms

Disease Spread

Tropical diseases move poleward

Ocean Issue

Acidification increases

Climate Evidence

Ice cores and CO2 data

Climate Effects

Warming, melting ice, rising seas

Population Impact

Coastal displacement

Marine Ecosystem Change

Affected by sea level rise

Positive Marine Effect

New habitats form

Negative Marine Effect

Less light reduces productivity

Wind Circulation

Moves heat around Earth

Wind Change

Climate alters jet stream and circulation

Ocean Conveyor Belt

Global current system

Ocean Current Impact

Affects climate and coasts

ENSO

Affects global weather patterns

Soil Impact

Temperature and rainfall changes affect soil

Erosion Risk

Can increase with climate change

Cooling Feedback

Ice reflects sunlight

Warming Feedback

Melting increases heat absorption

Permafrost Thaw

Releases methane

Methane Impact

Strong greenhouse gas

Polar Impact

Habitat loss for species

Ocean Warming

Caused by greenhouse gases

Ocean as Sink

Absorbs CO2

Coral Bleaching

Loss of algae causes whitening

Coral Sensitivity

Narrow tolerance range

Marine Changes

Affect metabolism and reproduction

Ocean Acidification

Lower pH from CO2

Acid Reaction

CO2 + H2O → H2CO3

Acidity Effect

More H+ lowers pH

Acid Causes

Fossil fuels and deforestation

Marine Damage

Shell formation decreases

Carbonate Loss

Reduces CaCO3 availability

Kyoto Protocol

1997 climate treaty

Kyoto Start

2005

Kyoto Countries

189 participated

Kyoto Goal

5% reduction below 1990 levels

Kyoto Limitation

Developing nations exempt

US Kyoto Decision

Withdrew due to economy concerns

Emissions Trading

Countries can trade allowances

Paris Agreement

2016 global climate agreement

Global Cooperation

Needed to reduce emissions

Reduce Emissions

Use renewable energy and efficiency

Transportation Fix

Drive less, use transit

Home Efficiency

Use insulation and efficient appliances

Lifestyle Changes

Conserve energy and buy sustainable