2.3 - environmental threats to our planet

2.3.1

definition of the quaternary period

• covers the last 2.6million years

• often called - ice age - due to Antarctica

2.3.1

explain the climate change from the beginning of quaternary period to now

• temperatures fluctuated wildly

• overall gradually cooled

• cold spikes = glacial episodes - ice age

• now = interglacial episode

• average temp today - higher than most of quaternary period

2.3.1

explain medieval warming period

• lasted from 950 to 1250AD

• some regions - temp equals today

• overall temp = lower than today

2.3.1

explain little ice age

• following the medieval warming period

• 1300 - 1870

• europe and north america = colder winters

• rivers + seas around UK froze

2.3.1

explain modern warming

• todays’ temperature increasing

• compared to average temp in 20th century - increased in last few decades

2.3.1

main evidence for climate change

• increase of average surface air temp by 1’C - last 100 years

• warmest ocean temp since 1850

• average rise in sea levels - 20cm since 1900

2.3.1

evidence for climate change - global temperature data

• over 1000 ground weather stations + satellite info → map global temp

• increased by 0.6’C by 1950

• LIMITATION - weather station - not evenly distributed (Africa) - reliable?

• data - only till 1880

2.3.1

evidence for climate change - ice cores

• oxygen, CO₂ and methane = found in ice cores

• estimate past temp = 800,000 years

• compare to present level

• scienctists - drill deep into ice in Antarctic + Greenland - extract thousand year old ice

• reliable

2.3.1

evidence for climate change - tree rings

• one tree ring = year of growth

• narrow rings = cool + dry past climate conditions

• wider rings = warmer + wetter past climate conditions

2.3.1

evidence for climate change - paintings + diaries

• suggest evidence of climate change through observations

• price increases in grain in Europe

• sea ice - prevent landing in Iceland

• people - emigrating - crop failure

• winter ‘Frost Fair’ - frozen River Thames

• art = much colder winter landcspes - 17th century

• cave paintings - draw animals - 11,000 + 40,000 years ago

• subjective and hard to date

2.3.2

explain how variations in energy from sun caused climate change

• sunspots = dark patches on sun’s surface

• caused by outburst of magnetic energy

• scientists - more sunspots = more heat is given off by Sun

• BUT - solar output = barely changed - cannot be responsible for climate change from 1970

2.3.2

explain how changes in the earth’s orbit caused climate change

distribution of sun’s energy = varies due to change in earth’s orbit.

• Axial tilt - spins on tilted axis

  • angle of tilt changes - gravitational pull from moon

  • angle of tilt - large = higher average temp

• Precession - ‘wobble’

  • as the earth spins during its rotations - it wobbles

• Eccentricity - earths orbit around sun

  • not fixed + changes over time

  • almost circular to slightly elliptical

  • cold period = circular

  • warm period = elliptical

2.3.2

explain how volcanic activity caused climate change

• huge quantities of ash, gas + liquid → into atmosphere

• sulphur dioxide + water vapour = volcanic aerosol

• this reflects sunlight away - reduces global temp

• wind - carries material far away - reduced temp experienced somewhere else

2.3.2

what is natural greenhouse effect

• natural occurring phenomenen

• keeps Earth warm enough for life to exist

1. sun’s infrared heat rays - enter Earth’s atmosphere

2. heat - reflected from Earths surface

3. natural layer of atmosphere + greenhouse gases = some heat is trapped + some heat reflected

2.3.2

what is enhanced greenhouse effect

• natural coauses = not responsible for current rise in temp

• human activity = cause

• increased layer of greenhouse gases - 77% CO2, 14% methane, 8% NOs, 1% CFCs

• less of sun’s energy = escape atmosphere - temp increases

2.3.2

name some human activities that contribute to enhanced greenhouse effect

• CO2 - burning fossil fuels, deforestation

• Methane - cattle rearing, rice paddy fields, decomposition in landfill

• NOs - exhaust fumes, agriculture + industrial processes

2.3.3 - global
social impact of sea level rise

• 600 million people = live coastal areas - 10m above sea

• environmental refugees - increase due to flooding

• migration + overcrowding - low risk areas - Asia

2.3.3 - global
economic impact of sea level rise

• agricultural land - lost to sea - Bangladesh

• world cities - affected - global finacial hubs - London + New York

• transport infrastructure - destroyed

• investment in coastal defences - increased pressure from sea level rise

• tourism - loss in income - beaches = flooded/eroded

2.3.3 - global
environmental impact of sea level rise

• 33% - coastal land + wetlands - lost in 100 years

• bleaching in coral reefs - loss of biodiversity

• mangrove forests - natural barrier - destroyed in storms

• fresh water sources polluted - salty seawater

2.3.3 - global
social impact of extreme weather events

• drought - affect farm + water supplies

• diseases - skin cancers + heatrstoke - temp increase

• winter deaths decrease - winters become milder

2.3.3 - global
economic impact of extreme weather events

• increase into investment - prediction + protection

• repair + damage costs - $9.7 billion in 2010 pakistan

• crop yields - decrease - 12% in South America - trade

2.3.3 - global
environmental impact of extreme weather events

• Forests = forest fires, more pests, disease

• food shortages - animals such as oranguatans

• flooding south asia - increase rice yields

2.2.3 - UK

economic impact on weather patterns

• summer heat - growth in tourist industry - Lake District - increase in jobs + revenue

• ski resorts - closed - lack of snow - reduce income

2.2.3 - UK

social impact on weather patterns

• elderly - more vulnerable - heat waves but suffer less - in winter

• water shortages - by 2050s

2.2.3 - UK

environmental impact on weather patterns

• vegetation + ecosystems - move north

• new crops - peaches + oranges - grow in south UK

• require increased irrigation

2.2.3 - UK

economic impact on sea level

• Thames barrier - expensive upgrading or replaced - increased risk of flooding

• industries - Teesside - vulnerable to sea level rise

• agricultural land - lost

• tourism industry - eroded beaches - negative

2.2.3 - UK

social impact on sea level

• flooding + cliff could collapse - properties at risk

2.2.3 - UK

environmental impact on sea level

• salt marshes - flooded + eroded

• managed retreat - new slat marsh habitats

2.2.3 - UK

environmental impact on seasonal patterns

• bird migration patterns - shift

• behaviour of wildlife + animals - change

• trees + plants - flower earlier/later

• wildlife species - struggle - food supply does not match

2.3.4 - main climate regions

Polar

LATITUDE - poles 90’N + S of equator

Characteristic:

• cold air from polar cell - sinks → high pressure

• spin of earth - dry, icy winds

2.3.4 - main climate regions

Temperate

LATITUDE - 50-60’N + S of equator

Characteristic:

• two air cells meet - one warm from Ferrel + one cold from Polar

• low pressure = created

• warm air meets cold air along a weather front

• frequent rainfall

• UK

2.3.4 - main climate regions

Subtropical

LATITUDE - 30’N + S of equator

Characteristic:

• Hadley + Ferrel cells meet = high pressure

• belt of desserts - Sahara

• daytime temp = more than 40’C

2.3.4 - main climate regions

Tropical

LATITUDE - at equator - 0’

Characteristic:

• Hadley cells meet - belt of low pressure

• air rises rapidly

• regular heavy rainfall + thunderstorms

• Malaysia - south east asia

2.3.4

how does global circulation work

• three large scale circular movement of air = cells

• act in each hemisphere

• take air from Equator - move it towards the poles

2.3.4

explain Hadley Cell

largest cells

• where - equator to 30’ N and S

• How - wind meets near equator - warm air rises = thunderstorms

• drier air flows out towards 30’N - before sinking over subtropical areas

2.3.4

explain Ferell cell

middle cell

• where - edge of hadley cell - 30’ to 60’ N + S

• how -

  • air in this cells joins the sinking air from Hadley

  • travels across mid-latitude regions

  • until air rises along the border of cold air with polar cell

2.3.4

explain polar cell

smallest + weakest cell

• where - edge of ferrel cell to poles at 90’

• how

  • air sinks over higher latitudes at poles

  • flows towards mid-latitudes

  • where it meets with ferrel cell and rises