2 w&c overview ppt
TRANSCRIPT
Weather and Climate and Associated Weather and Climate and Associated Hazards AQAHazards AQA
Contents Contents
1. Major climate controls
2. The climate of the British Isles
3. The climate of one tropical region: Tropical monsoon climate
4. Urban climates
5. Global climate change
MesosphereExtends to 85km above the earths surface. The layers in which most meteors will burn up.
StratosphereThe ozone layer (O³) is mainly concentrated at 15 – 35km in the stratosphere. The stratosphere extends to 51km above the earths surface.
Major Climate Controls: Major Climate Controls: The structure of the atmosphereThe structure of the atmosphere
Atmosphere (air) a layer of transparent gases surrounding the earth held in place by gravitational pull.
TroposphereRanges from the Earth’s surface to 7km at the poles to 17km at the equator. An unstable layer containing the majority of the earths climate and weather. 99% of the total mass of the atmosphere is found in this layer; 50% of it is below 5.6 km, and contains 99% of water vapour.
TropopauseAn isothermal layer: constant temperatures.
Stratopause
Mesospause
ThermosphereExtends to over 640km from the earth’s surface.The International Space station orbits at around 350km.
The structure of the atmosphere: The structure of the atmosphere: TemperatureTemperature
• Lapse Rate the decrease of temperature with height.
• Troposphere the temperature decreases by 6.4°C every 1000m. At the tropopause temperatures drop to - 60°C.
• Stratosphere a temperature inversion occurs: temperatures steadily increase reaching almost 0°C due to the ozone layer absorbing ultra-violet radiation.
• Mesosphere the temperature decreases to almost -100°C as radiation can not be absorbed.
• Thermosphere an inversion as temperature rises due to solar radiation being absorbed by the presence of atomic oxygen.
The structure of the atmosphere:The structure of the atmosphere:CompositionComposition
N² Nitrogen important for plant growth
O² Oxygen product of photosynthesis
Ar Argon
CO² Carbon dioxide used for photosynthesis
Ne Neon
He Helium
CH4 Methane
Kr Krypton
H² Hydrogen
Solar energy affects:
• Climate
• Atmospheric motion
• Ocean currents
• Precipitation
• Temperature
The incoming solar radiation is short-wave; insolation. As the Earth heats up it radiates its own heat in the form of long-waves (infra-red); terrestrial.
The albedo is the percentage of radiation that is reflected. This depends on the type of surface.
The atmospheric heat budgetThe atmospheric heat budget
• There are several aspects that control the amount of incoming solar radiation:– Sunspot activity– Elliptical Earth’s orbit– Day and night– Latitude
Ave
rage
net
rad
iatio
n (w
/m²)
0
25
25
50
50
100
100
125
125
020 2040 4060 6080 80degrees from equator
Radiation balance at Earth’s surface
How is the positive heat balance (net gain in heat radiation from the sun) within the Tropics transferred?
1. Horizontally
2. Vertically
Air movements, including winds, jet stream, cyclones, depressions. These account for 80% of heat transferred. Ocean currents transfer the remaining 20%.
Conduction, convection and radiation.
positive balance
negative balance
The atmospheric heat budgetThe atmospheric heat budget
Radiation balance in atmosphere
Net radiation gain
General atmospheric circulationGeneral atmospheric circulation
Energy surplus
Energy deficit
Energy deficit
Winds blow from areas of high pressure to areas of low pressure. If the Earth did not rotate a single convection cell would operate in both hemispheres.
Heat is re-distributed by ocean currents and wind
As air moves from high to low pressure in the northern hemisphere, it is deflected to the right by the Coriolis force. In the southern hemisphere, air moving from high to low pressure is deflected to the left by the Coriolis force.
General atmospheric circulationGeneral atmospheric circulation
All points on the earth’s surface have the same rotational velocity (they go round once per day).
An object travelling away from the equator (e.g. wind) will eventually be heading east faster than the ground below it and will seem to be moved east by some mysterious "force". This movement is eastwards in the northern hemisphere and westwards in the southern hemisphere.
The diagram illustrates how it affects winds in both hemispheres.
High pressure
Low pressure
due to the earth’s rotation
UK
Equator low
high
high
low
low
60
60
North Pole Equator
Hadley
cell
30o
High pressure
Divergence zone
Low pressure
Convergence zone
60o
Low pressure
Convergence zone
High pressure
Divergence zone
North-east trade winds
Heat from the Sun most intense at the Equator
ITCZ
Heavy convection
rainfall
Air cools and sinks
Air gets deflected
northwards
Warm air rises and becomes unstable
South-westerlies (winds)Easterlies (winds)
Ferrel
cell
Warm air rises
Warm air from the tropics meets cold air from the pole
at the POLAR FRONT causing depressions
Polar
cell
Cold air sinks
Dry and stable
Dry and stable
Atmospheric circulation: the tricellular modelAtmospheric circulation: the tricellular model
Trade winds pick up latent heat
Air that does not travel to next cell returns to Equator as trade winds
The Hadley cell is the largest due to the intense heating of the Earth’s surface at the Equator.
The Intertropical convergence zone (ITCZ)The Intertropical convergence zone (ITCZ)
Cumulo-nimbus clouds along the ITCZ
• The ITCZ is the region that circles the Earth, near the Equator, where the trade winds of the Northern and Southern Hemispheres come together.
• The intense sun and warm water at the Equator heats the air in the ITCZ, raising its humidity and causing it to rise.
• As the air rises it cools, releasing the accumulated moisture in an almost constant series of storms.
• Variation in the location of the ITCZ drastically affects rainfall in many equatorial nations, resulting in the wet and dry seasons of the tropics rather than the cold and warm seasons of higher latitudes.
• A shift in the ITCZ can have serious ramifications delaying the rainy season resulting in drought, for example the drought in the Sahel during the 1980s.
The location ITCZ changes seasonally; south in January and north in July. This causes monsoons.
• Winds are the movement of air in the atmosphere.
• Wind speed is affected by a number of factors that operate on a variety of scales. These include:
• the pressure gradient, • Rossby waves. • jet streams. • and local weather conditions such as sea
breezes and urban winds.
• Wind speed depends on how large the difference is because the greater the difference, the faster the wind moves between the two points as it attempts to equalise the pressure.
• Local weather conditions can also influence wind speed as the formation of tropical storms and hurricanes can drastically affect the velocity of the wind.
Planetary surface windsPlanetary surface winds
Jet stream
These are bands of strong winds blowing around the globe in the upper atmosphere (about 10km to 15km above the surface). They drive surface weather systems like depressions. A slight change in their path is what caused the very wet summer in 2007.
Rossby WavesRossby Waves
Jet streams are bands of even faster winds (300km/hr) within the Rossby waves at about 10km above the surface. Commercial airlines often make use of them to reduce fuel consumption.
There are two jet streams:
• The Polar Jet above the Polar Front (the
boundary between polar and mid-latitude cells).• The Subtropical Jet (between Ferrel and Hadley cells) which exists as a mechanism to transport moisture and energy from the tropics polewards.
Jet streamsJet streams
Ocean CurrentsOcean Currents
Atmospheric processes are closely linked to the oceans because they store massive amounts of heat energy (and water) which has a major influence on weather and climate. They are involved in the horizontal transfer of heat with warm currents carrying water towards the poles and cold currents towards the Equator. This has the effect of raising or cooling the surrounding sea and air temperature which affects coastal climate.
Why does temperature decrease with altitude?Why does temperature decrease with altitude?
Temperature drops by 6.5°C every 1000 metres.
The climate of the British IslesThe climate of the British Isles
The British Isles has a Cool Temperate Western Maritime Climate.
It has: • Clearly defined
seasons • Warm summers;
12°C to 20°C • Mild winters• Low temperature
ranges
Climatic characteristics: precipitation Climatic characteristics: precipitation
West: Areas of high land are parallel to the coast
East: Drier conditions. Area of rain shadow
Orographic rainfallOrographic rainfall
Climatic conditions: temperatureClimatic conditions: temperature
50°
55°
60°Due to the influence of latitude the south of the British Isles has warmer summers and milder winters than the north.
Due to continentality the east of the British Isles has warmer summers and colder winters than the west.
Summer: 14 °C
Winter: 3 °CSummer: 14 °C
Winter: 6 °C
Summer: 16 °C
Winter: 7 °C
Summer: 18 °C
Winter: 4 °CPrevailing wind
Climatic conditions: windsClimatic conditions: winds
Anabatic flow (day) Katabatic flow (night)
Surface is heated by insolation.
Warm air rises up the gradient.
Warm air becomes unstable. Clouds are formed
Descending cool air leaves the centre of the valley clear
At night the air cools and as it become denser it sinks down the valley sides into the valley.
Fog may form in winter
Air masses affecting the British IslesAir masses affecting the British Isles
An air mass is a large body of air in which temperature and humidity are almost uniform horizontally but change vertically within. They are classified by their surface temperature and humidity.
The temperature, humidity and stability of an air mass alters as they are influenced by the surface over which they travel.
Air masses affecting the British IslesAir masses affecting the British Isles
Polar Maritime Air MassSource region: Canada and Arctic Ocean.
Tropical Maritime Air MassSource Region: the Azores
Tropical continental Air MassSource Region: North Africa
Polar continental Air MassSource Region: Siberia & East Europe.
Arctic Maritime Air MassSource Region: Arctic Ocean.
Frontal depressions occur when Pm and Tm meet
See Teacher’s notes for more information
Origin and nature of depressionsOrigin and nature of depressions
Depressions occur along the polar front where Tm and Pm air masses meet.
They are low pressure weather systems; how low the pressure falls is determined by the rate at which air rises from the surface. Average pressure is 1013mb.
The speed at which a depression travels is determined by the speed of the jet stream in the troposphere. The life cycle of a depression is normally 3-5 days.
Formation of a depressionFormation of a depression
Weather changes associated with depressionsWeather changes associated with depressions
Weather changes at the warm frontWeather changes at the warm front
Dew point
Source of anticyclones: Dry air in the upper layers of the atmosphere.
As cool dry air descends its temperature increases at the dry adiabatic lapse rate DLRA. High pressure
is created at surface.
Weather is drier and more stable at the surface. The pressure gradient is gentle resulting in light clockwise
winds.
Origin and nature of an anticycloneOrigin and nature of an anticyclone
In the UK anticyclones are associated with extended warm, dry conditions in the summer and cold, frosty and sometimes foggy conditions in the winter. An anticyclone may be 2500 km in diameter, although many are smaller.
clockwise
The synoptic chart for a mid-latitude anticyclone
The satellite image shows the cloudless skies associated with high pressure systems. They may remain for a number of weeks causing heat waves across many parts of Europe during the summer.
Origin and nature of an anticycloneOrigin and nature of an anticyclone
Origin and nature of an anticycloneOrigin and nature of an anticyclone
Associated weather conditions of Associated weather conditions of anticyclones in winter and summeranticyclones in winter and summer
Anticyclonic weather in the UK
Winter conditions (Polar source Summer conditions (tropical source)
Conditions Impacts Conditions Impacts
Cold day time conditionsUsually below freezing
Ice. Increase in accidents particularly elderly Increased power use
Hot daytime conditions over 23o
Increase in heart attacks/heat stroke Increase in sales of lettuce/ice cream/soft dinksHose pipe bans/drought
Very cold at night with frosts Roads need gritting Warm at night Sleeping difficulties
Clear skies Temperatures remain low Generally clear skies Sunburn/sunstroke
Stable conditions may produce fog
Car accidents Disruption to transport (aircraft, ferries, trains)
Some early morning mists especially at coast
May take a while to clear impacted tourists
High levels of pollution due to lack of wind
Breathing difficulties Thunderstorms may form in evenings due to convection
Flash flooding effects homes and transport
Subsiding air traps pollutants Hospitals admissions increase
Photo-chemical smog and low level ozone trap heat
Increase in deaths from asthma/breathing conditions
• June to August 2003
• Over 2,000 died in the UK between 4–13 August 2003.
• Highest temperature recorded in Kent : 38.5°C
• Over 30,000 deaths in Europe.
• £7 billion in crop loss.
• Railway tracks buckled.
The map shows the temperature variations from normal in Summer 2003.
Storm events in the British Isles: Storm events in the British Isles: Boscastle 2004Boscastle 2004
• August 16th 2004• Large depression in Eastern Atlantic, sucking in
warm moist air – including the remnants of Hurricane Alex
• Blew in from the sea in prevailing SW direction• Met with SW wind and created convergence• Also, intense uplift that morning in Cornwall
due to warm, sunny conditions – cumulonimbus rose to 40,000ft.
• Intense, very localised storms.• 200mm of rain in 24 hours, over 300mm per
hour at peak intensity.• Most between midday and 5pm on the 16th on
high ground to the east. • Already saturated catchment – rapid runoff.• Boscastle lies in a deep valley just downstream
of the confluence of the rivers Valency and Jordan.
• 2 metre rise in river levels in one hour, floodwater velocity of 10mph.• Est. 2million tonnes of water flowed through Boscastle that day.• Debris caught under narrow bridge caused 3m high wave of water which
burst down main street when bridge collapsed.• 84 cars recovered after being swept away; 32 never seen again!• Significant structural damage – 58 properties affected, 4 swept away.• 100 people air lifted to safety but no loss of life.• 300 metres of sewers damaged or destroyed.• Cost of damage estimated at £2million.
Storm events: Boscastle 2004 - impactsStorm events: Boscastle 2004 - impacts
Storms events: Boscastle 2004 - responseStorms events: Boscastle 2004 - response
• Large relief culvert completed in April 2005 to divert flood water from River Jordan.
• Widening and deepening of the River Valency upstream of Boscastle..
The flood management improvements in Boscastle since the 2004 floods:
The cost of the River Valency works, car park and bridge work is about £4.6 million, although it will still not prevent a flood as severe as the 2004 event, which has a chance of about 1 in 400 of occurring in any one year.
• Car park raised in December 2006, using stones removed from bed of River Valency during widening and deepening works.
• Old stone lower bridge demolished – it was over 100 years old and trapped 14 cars beneath and behind it in the 2004 flood.
The location of tropical climatesThe location of tropical climates
Equator
The ITCZ influences the location of tropical climates. Its northerly and
southerly limits are shown on the map.
Tropical climates are located between the Tropic of Cancer and Tropic of Capricorn.
Tropic of Cancer
Tropic of Capricorn
ITCZ
ITCZ
The climate of a tropical region: The climate of a tropical region: the Monsoon Climatethe Monsoon Climate
Monsoon is the reversal of wind direction that results in a clearly defined wet and dry season.
Locations that receive the majority of their rainfall in one season have a monsoon climate. They are found in coastal regions of south Asia, Southeast and north east Brazil, northern Australia, West Africa.
Monsoon rainfall, Kerela, India
Gujarat, India July 2005 under monsoon rains and suffering from serve floods
Gujarat before the start of monsoon
The cause of the monsoon climate - IndiaThe cause of the monsoon climate - India
In mid- summer the ITCZ has move north over India.
Strong insolation causes surface temperatures to increase; low pressure causes rapid uplift of warm air.
Moist air is sucked in to replaced rising air. Heavy orographic rainfall can occur.
In winter the ITCZ has moved south. The North easterly trade winds blow south into Equatorial Low.
Trade winds cause off shore winds to blow across India
High pressure over land as cool air descends from the Himalayas. Dry conditions prevail.
Air cools and sinks over ocean
The characteristics of the The characteristics of the Monsoon climateMonsoon climate
March – May: Highest temperatures and very dry. A period of drought.
June – September: Heavy rainfall. High humidity as the temperatures remain hot.
October to February: Dry season. Little precipitation. Temperatures not as hot as in March to May period.
Monsoon clouds over Lucknow, India.
Climate statistics for Mumbai & New DelhiClimate statistics for Mumbai & New Delhi
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Average Temp. (°C)
23.5
23.5 26 28 30 29 27 26.5 26.5 28 27.5 26
Precipitation (mm)
2.5 2.5 2.5 0 18 485 617 340 264 64 13 2.5
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Average Temp. (°C)
14 16.5 22.5 28 33.5 33.5 31.5 30 29 26 20 15.5
Precipitation (mm)
23 18 13 8 13 74 180 173 117 10 3 10
Mumbai
New Delhi
Sub-tropical anticyclonesSub-tropical anticyclones
30°N
30°S
Sahara Desert
Namib Desert
Kalahari Desert
Equator
The Sahel
Prolonged period of drought during the 1980s. The fluctuating location of the ITCZ and its progression south linked to El Nino events is one cause of droughts in this region.
Tropical depression (winds less than 38 mph)
Tropical storm (winds 39 – 73 mph)
Hurricane (winds >74 mph)
Tropical revolving storms are very low pressure weather systems with strong winds and heavy rainfall. They get their energy from the sea and begin to die out when they are over land.
Tropical revolving stormsTropical revolving storms
The aftermath of a tropical storm
Tropical revolving stormsTropical revolving storms
Tropical storms 1994 - 2005
Hurricanes:Atlantic Ocean
Cyclones:Indian Ocean Willy-willies:
Australia
Typhoons:Pacific Ocean
named storms
major hurricanes
2005 was the worst year on record for hurricanes
An average of 7.7 named storms and 3.6 major hurricanes since 1995 compares to 5 storms and 1.5 major hurricanes from 1970-1994.
The occurrence of tropical revolving stormsThe occurrence of tropical revolving storms
Warm (> 27°C), shallow (<60m) seas
Strong upward movement of air draws water vapour up
Rising air spirals, cools and condenses – cumulonimbus clouds
bring torrential rain and thunder
Colder air sinks in the centre – the ‘eye’
Formation of a tropical stormFormation of a tropical storm
Source; NOAA
eye
vortex of rotating clouds (300km across)
eye wall
Cirrus canopy
torrential rain squally showers
Case study: Hurricane Katrina 2005Case study: Hurricane Katrina 2005
August 25th Category 1* < 95 mph (< 155 km/ hr)
August 26th Category 2* 100 mph (160 km/ hr)
18 hours later Category 3* 115 mph (185 km/ hr)
August 28th Category 4* 145 mph (235 km/ hr)
Six hours later Category 5* 160 mph (255 km/ hr)
* on the Saffir- Simpson scale
Hurricane Katrina first appeared on August 23 as a tropical depression just west of the Bahamas.
Case study: Hurricane Katrina 2005Case study: Hurricane Katrina 2005
The animated sequence shows the path of Katrina on the 29th August 2005 as it crossed the Caribbean and moved towards the southern states of the USA. Eventually it struck land with devastating consequences for the people of New Orleans and the surrounding areas.
New Orleans
Case study: Hurricane Katrina 2005Case study: Hurricane Katrina 2005
Failure of the levées surrounding New Orleans caused the greatest damage.
LandfallLandfall
Winds speeds of 280 km per hour. Red = hurricane force winds.
Up to 380mm of rain in places.
Storm surges, peaking at 8.5m high.
Hurricane Katrina made landfall at 6.10am in Louisiana 29th August
Strongest ever recorded hurricane to make landfall in the USA.
Hurricane Katrina: ImpactsHurricane Katrina: Impacts
• By August 31st 80% of New Orleans lay under water.
• 1.7 million people without electricity.• $150 billion estimated total economic
impact.• 1464 died in Louisiana.• Almost everyone instantly unemployed!• Estimated 600,000 pets killed.• Lack of clean water, food and toilet
facilities.• Oil and natural gas industry affected.• Communications and transport
infrastructure damaged and failed.
Why were the impacts so severe in Why were the impacts so severe in New Orleans?New Orleans?
Managing the riskManaging the risk
New Orleans waterfront
To repair the defences in New Orleans they:
• Repaired the levees – breached levees repaired and all levees to be raised by 2010. New floodgates to be built at canal entrances.
• Restored the wetlands – The $14 billion, 30-year ‘Coast 2050’ plan to recreate the mixture of swamp, marshland and barrier islands to protect places inland as before.
How can New Orleans be prepared for another hurricane like Katrina?
• Preparation - National Hurricane Centre watches and produces warnings. It also runs a ‘hurricane preparedness week’ every year for the public. DHL also run schools workshops on hurricane preparedness
• Evacuation – evacuation order given on 28th August 2005 by Mayor. However, it’s hard to predict the path, very expensive and not everyone is able to leave. In advance of Hurricane Gustav – which was heading for New Orleans at the end of August 2008 – the Mayor of New Orleans ordered an evacuation to prevent a similar disaster. Over 90% of residents left the city.
Case study: Cyclone Nargis 2008Case study: Cyclone Nargis 2008
April 27th: formed in Bay of Bengal
Originally predicted to hit Bangladesh or SE India
Convection decreases
Convection increases, Changes direction eastwards
May 1st
Landfall May 2nd Burma.Peak winds of 215 km/h
Category 4
Dies outs May 3rd
Cyclone Nargis May 2008: The impactsCyclone Nargis May 2008: The impacts
146,000 fatalities1000s missing.
Many feared washed out to sea
2.7% of projected GDPpredicted lost by event
1,163 temples destroyed
Extensive destructionof buildings, e.g. Labutta
town 75% buildings collapsed
700,000 homes destroyed in delta
5 regions declareda disaster area $10 estimated cost
65% of paddy fields contaminated by
salt water
75% of health service& 4,000 schools
damaged
100,000 fishing vessels destroyed
75% livestock killed
Cyclone Nargis May 2008: the responseCyclone Nargis May 2008: the response
• Long term response has been to restore quality of life through projects working with farmers, rebuilding school and health centres and clean water supplies.
• Improving road infrastructure to allow for quicker access to safer areas in future disasters.
• Preparation to prepare people in most vulnerable areas and educate on appropriate response.
• 44 countries responded by donating money to the relief operation, food, shelter, volunteers, water and medicine.
Climate on a local scale: urban climatesClimate on a local scale: urban climatesUrban heat island effectUrban heat island effect
A micro climate is the climate of a small area. Temperature, precipitation, wind and atmospheric gases are distinctly different in an urban area to that of a rural area. An urban heat island describe how temperatures are highest at the centre of the urban area and decrease towards the suburbs.
Urban areas are warmer because:
• Industries, homes & vehicles burn fuel realising heat.
• Pollution from industry and vehicles traps heat.
• Dense and dark coloured surfaces of buildings and roads absorb heat.
• Small amounts of water and vegetation so little energy is used in
evapotranspiration.
Temperatures are greatest where the Temperatures are greatest where the building density is highestbuilding density is highest
Urban climates: Precipitation and windUrban climates: Precipitation and wind
There is 5 – 30% more rain in urban areas than in rural area due to a greater density of condensation nuclei allowing for cloud formation
There is 14% less chance of snow in urban areas than rural areas due to the increased temperatures
Thunderstorms are 25% more likely urban areas due to strong convectional uplifts of warm air
There is 10 times more condensation nuclei in urban areas and this can lead to a 100% more likelihood of fog in winter and 30% more in summer. Wind speed is
20% less in urban areas are the building act as barriers.
Tall buildings can channel wind resulting in strong gusts. Prevailing winds blow pollution and rain
clouds. Consequently the west of London was traditionally more desirable
Urban climates: air quality Urban climates: air quality
Pollution is trapped below the warm inversion layer causing a pollution dome to form.
Photochemical smog is caused as above normal levels of nitrogen dioxide and ozone are produced when pollution and sunlight react.
Smog occurs during anticyclones. A temperature inversion is causes as cool air sinks to replace the rapid uplift of warm air.
Global Climate ChangeGlobal Climate Change
Climate varies on all time scales from the short –term (the recent retreat of glaciers) to the long-term (deposition of desert sediments to form sandstone) in response to random and periodic forcing factors.
Present day ice limit
Ice limit in 1946
Extent of glacier retreat in little over 50 years
Some of these could be due to short-term changes e.g. random variations in the climatic systems.
Evidence for past climate changeEvidence for past climate change
Evidence for past climate changeEvidence for past climate change
Other techniques include studying glacial advances/retreat, ice cores, isotope analysis, geology, pollen, dendrochronology and archaeological/historical data.
Past sea levelsThe ice ages brought eustatic change. Sea levels fell as huge volumes of water were transferred to glaciers and ice caps. Subsequent melting would then cause an increase in sea level. Such changes are termed glacio-eustatic.
Measuring sea level changeAccurate measurements can be made of past sea levels by observing one or more of the following features.1. Shoreline deposits such as shells, wood and peat found in marine cores.2. Exposed rock outcrops containing marine fossils.3. Vegetated tidal flats above the high water mark.4. Exposed coral reefs.5. Marine rocks displaying evidence of wind-borne erosion.
Past sea levels were up to 200m above present during interglacials and 100-150m below present during glacials.
Evidence for past climate changeEvidence for past climate change
Climate change can take three forms:1. Short-term change
Climate since the end of the last ice age (hundreds/thousands years) Very short-term: El Nino, La Nina.
2. Long-term change Global climate over billions of
years.
3. PaleoclimatesClimates from thousands / millions of years ago.
The causes of climate changeThe causes of climate change
Earth’s surface warms up and emits longwave radiation (re-radiates energy)
Shortwave radiation reaches Earth’s atmosphere
Some is reflected
Earth absorbs the radiation
Most gets through
Some of the re-radiated long wave radiation is trapped by water vapour and “Greenhouse gases” (CO2 CFCs, CH4, N2O)
Global warming: causesGlobal warming: causes
Global warming – Global warming – Natural cycle v human impactNatural cycle v human impact
The current scientific consensus is that global warming is a real threat and it is a result of human activity. However, some people continue to debate whether global warming actually exists and/or whether it is as a result of human activity. The evidence for past climate change is often cited to explain the current changing conditions.
Carbon dioxide
emissions since 1840
Most scientists agree that global warming is being caused by human effects on the atmosphere, principally through carbon dioxide emissions.
Global warmingGlobal warming
Rank Country
1 USA
2 China
3 Russia
4 Japan
5 India
6 Germany
7 Canada
8 UK
9 Italy
10 South Korea
Top ten carbon dioxide emitters.
USA and China are the two greatest emitters.
Effects of global warming Effects of global warming on a global scaleon a global scale
• Bangladesh is very densely populated.
• Many fresh water fishing resources are under threat.
• Fishing generates substantial income and any intrusion of salt water would disrupt the economy.
• Storm surges are also a threat; cyclonic storms occur frequently and with devastating effects.
Sea level threats to Bangladesh
The effects of global warming on The effects of global warming on BangladeshBangladesh
The effects of global warming The effects of global warming on the British Isleson the British Isles
National/Local government policy
Public / individuals
International agreements
Rio Earth summit
IPCCKyoto
UK policy Local agenda 21
Pressure groups
Changing lifestyles
Response to global warming on a Response to global warming on a international, national and local scaleinternational, national and local scale
Coping with climate change Coping with climate change – – Earth SummitEarth Summit
In June 1992 at Rio de Janeiro in Brazil, the Rio Earth Summit, was the largest environmental conference ever held. It attracted more than 30,000 people and over 100 Heads of State. The aim of the conference was to address the growing global environmental problems and to agree major treaties on climate change, forest management and bio-diversity. A number of key principles came from the Rio Declaration including:
A key outcome was The Framework Convention on Climate Change.
Coping with climate change –Coping with climate change – Kyoto Protocol Kyoto Protocol
• On 16th February 2005 the 1997 Kyoto Protocol became international law. • The Protocol was agreed in Kyoto, Japan in 1997 to implement the United
Nations Framework Convention for Climate Change .• Industrialised nations who signed up to the treaty were legally bound to
reduce worldwide emissions of six greenhouse gases by an average of 5.2% below their 1990 levels by the period 2008-2012.
• The agreement needed to be ratified by countries accounting for at least 55% of 1990 carbon dioxide emissions.
• The USA believes implementation will have a devastating effect on it’s economy. However, President Obama has taken steps forward in promoting renewable energy and reducing carbon emissions.
Coping with climate change – IPCCCoping with climate change – IPCC
The Intergovernmental Panel on Climate Change (IPCC) was set up in 1988 to assess information regarding climate change and the impact on the planet. Since 1988 it has produced four reports, the last in 2001.
It is involved in a monitoring programme which carries out the following activities:
• Remote observation of the atmosphere at surface and trophosphere level.• Monitoring and measuring ocean temperatures.• Monitoring and measuring greenhouse gas levels in the atmosphere.• Monitoring sea-level rise and glacial and ice sheet retreat.
• Climate change summit held in Copenhagen in December 2009.
• There was disappointment expressed by some environmental groups and observers at the outcomes of the summit.
Demonstrators at the Copenhagen summit
Photo credit: EPO on wikipedia.
Tackling climate change – UK policy 1Tackling climate change – UK policy 1
So what are the present UK policies?
• Sustainable energy usage, energy conserving houses, grants for efficient gas boilers etc.
• Waste strategies including recycling to avoid methane from landfill. Currently, in 2004 around 17% of waste is recycled.
• Move to renewable sources of power, combined heat and power systems and cleaner coal.
• Green transport strategies (clean lean burn)- car engines, fuel efficiency, new fuels, car parking (e.g. Winchester’s extended Park & Ride and MIRACLES project) working patterns, public transport. Indirectly, London’s Congestion Charging will help.
Tackling climate change – UK policy 2Tackling climate change – UK policy 2
• Air quality regulation- strict Environment Agency and EU requirements.
• Planning regulations: encouragement of compact cities and avoidance of urban sprawl e..g through the Greenbelt policy. The map shows greenbelts in the UK.
• Carbon emissions trading scheme - setting caps on emissions in industry.
• Technological innovation - supporting research and development into new long term options. In March 2001, the Carbon Trust was launched to promote low-carbon technology and innovation in the UK.
• The Climate Change Levy (CCL) is a tax on the use of energy in industry, commerce and the public sector.
Coping with climate change Coping with climate change – Kyoto Protocol– Kyoto Protocol
As an NIC, China is considered an Annexe II country, which means it is not required to reduce emissions under the Protocol yet it emits more carbon dioxide than any nation in the region and 50% of emissions from all LEDCs.
As with most LEDCs, China is more vulnerable to the effects of climate change than MEDCs. It has increasing hazards of coastal and river flooding, drought, landslides, storms and tropical cyclones. Rising sea levels could flood low lying areas along the Yellow and Yangtze rivers and the Pearl river delta which would affect 70% of the population and 80% of industrial output.
River transport on the Yangtze.
Coping with climate change Coping with climate change – Local agenda 21– Local agenda 21
Agenda 21 was established during the 1992 Rio Earth Summit. A framework for future action on global sustainable development was agreed. However, sustainable development cannot be achieved on a global scale unless it is tackled at a local level, with all local authorities adopting Local Agenda 21 into their strategies. 'Think Globally, Act Locally.'
To put sustainable development into practice at a local level each local authority must create a strategy. All local authorities must incorporate sustainable development into every aspect of their work. The strategies should not be designed to work along side projects, they should inform what the project should be.
With the cooperation of local business, schools, transport companies and the wider community Oxford County Council has attempted to reduce road traffic intensity along with its associated pollution. The city of Oxford has been the main focus.
Strategies aim to reduce the 60% car use within the city and involve two action plans – Travelwise and the Transport Action Plan. These include:
• Funding for the Sustrans cycle network across the county• Increased funding for rural bus services. • Green commuter plans from employers such as car share / bus
provision. • Walk to school week. • Provision of sustainable transport seminars for business • Car free days.
Coping with climate change Coping with climate change – Local agenda 21– Local agenda 21
Coping with climate change – Coping with climate change – Changing lifestylesChanging lifestyles
There are a many small changes to our lifestyles that can be made to achieve a more sustainable society and help reduce climate change.
Energy and resourcesTurn off electric and gas appliances such as TVs, lights and computers when not in use. Insulate/double glaze your home to save energy. Use low energy light bulbs and appliances. Only fill the kettle with the water you need. TransportWalk, cycle and use public transport whenever possible. Take fewer car journeys and share cars.
ShoppingAvoid products with lots of packaging and reuse carrier bags. Buy environmentally friendly products. Buy local food produce, think of food miles.
Reduce WasteReuse bags, bottles and containers. Have things repaired or try to fix them. Recycle rubbish. Raise environmental awareness.
Coping with climate change Coping with climate change – Pressure groups– Pressure groups
Friends of the Earth – www.foe.co.uk
The Climate Group – www.theclimategroup.org
The Carbon Trust – www.thecarbontrust.co.uk
Greenpeace – www.greenpeace.org
The Global Climate Coalition (guided USA against Kyoto) - www.globalclimate.org
World Wildlife Fund – www.wwf.org.uk
Exam questionExam question
Explain the conditions that lead to the formation of tropical storms. (6 marks)
Tropical storms can be formed where low pressure weather systems occur over seas and oceans with surface temperatures greater than 27°C. For example in the tropical regions, (between the tropic of Cancer and tropic of Capricorn), of the Atlantic Ocean resulting in hurricanes and in the Indian ocean where they are known as cyclones. They require strong updrafts of warm moisture laden air that cools and condenses to form cumulo-nimbus clouds that bring torrential rainfall. The effect of the coriolis force causes the rotation of the air mass which is anti-clockwise in the northern hemisphere and clockwise in the southern hemisphere.
2 specific facts givenExamples
provided
Specific use of geographical terminology
Good explanation to support facts.
Exam questionExam question
Essay question: Discuss the view that human activity is causing climatic change.
IntroductionHow is the climate changing?
What is global warming?
What evidence is there for climatic change?
Main BodyEvidence to suggest change is due to human activity.
Evidence to suggest change is due to factors other than human activity.
Short term changes in climate since last ice age and impact of El Nino and La Nina
Paleoclimate trends
Source of green house gases from human activity and their relative importance.
Sources of methane
Sources of CO²
Sources of CFCs
Conclusion
Evaluation of evidence and a personal opinion