The Main titles for this topic section are:
- Major Climate Controls
- The Climate of the British Isles
- Tropical Climates
- Climate on a local scale: Urban Climates
- Global Climate Change
Major Climate Controls
- Structure of the atmosphere
- Atmospheric heat budget
- Planetary surface windss
- Atmospheric pressure and winds
- General atmospheric circulation system (The Hadley, Ferrel and Polar Cells)
- Oceanic Circulation, Latitude, Altitude
The Climate of the British Isles
- Temperature, Precipitation, Wind
- Air masses affecting the British Isles
- The origin and nature of depressions (Formation of a depression and weather conditions)
- The origin and nature of anticyclones
- Associated weather conditions in winter and summer
- Fogs
- Storm events: Atmospheric processes; Impact
Tropical Climates
- Inter-Tropical Convergence Zone
- Equatorial Climate
- Tropical Wet and Dry Climate
- Tropical Monsoon Climate
- Tropical Revolving Storms (Distribution, Magnitude and Frequency, Impacts, Prediction)
Climate on a local scale: Urban Climates
- Temperatures: The Urban Heat Island Effect (Changes over time and space)
- Precipitation
- Fog; Thunderstorms
- Air Quality (Particulate pollution and Photochemical Smog, Reduction Policies)
- Winds
Global Climate Change
- Evidence for Climatic Change (Pollen Analysis, Dendrochronology, Ice-Core Analysis, Sea-Floor Analysis, Radiocarbon Dating, Coleoptera, Changing sea levels, Glacial Deposits, Historical Records, Recent Evidence for Global Warming)
- Possible Causes of Climatic Change (The Enhanced Greenhouse Effect)
- Effects of Global Warming (Rising Sea Levels, Climatic Change, Extreme Events)
- Effects on Tropical Climate
- Effects on the British Isles (Coastal Regions, Agriculture, Flora, Fauna and Landscape, Soils, Water Resources, Energy Use)
- Responses to Global Warming (International Responses, National Responses: The UK, Local Responses)
Major Climate Controls
The
Atmospheric Layers
·
Earth made up of 4 layers and 3 isothermal
layers
Thermosphere:
·
Temperatures increase rapidly with height to
as much as 15000c
Cause by an increasing proportion of
atomic oxygen absorbing incoming UV radiation.
Mesophere:
·
Temperature
decreases rapidly as there is no water vapour, cloud, dust or ozone to absorb
incoming radiation. Temp as low as -90oc
·
Strongest
winds – 3000km/h
·
Mesopause
layer shows no temperature change.
Stratophere:
·
Steady
increase in temp, caused by the increase in the ozone layer (O3).
This gas absorbs ioncoming UV radiation.
·
Winds
increase speed with height
·
Pressure
continues to decrease & the air is dry
·
Meteorites
will usually burn this layer
·
Stratopause
is another isothermal layer.
Troposhere:
·
The layer that mainly concerns us as it is
responsible for day to day weather
·
Temperature decreases 6.40c with
every 1000m increase in height
·
Solar radiation heats the land, which in turn
heats the air next to it, by conduction, convection and radiation
·
Wind speed increases with height
·
Unstable layer, containing most of the
atmosphere’s water vapour, clouds, dust and pollution.
·
The upper limit is the tropopause, in which
the temperature is constant.
Here are 2 videos that will
help with the learning of the atmospheric layers…
·
Below shows – the vertical
sttucture of the atmosphere
·
Below shows the heat budget:
·
depends
on balance between incoming solar radiation
and outgoing radiation from the planet.
·
The
atmosphere has a net deflict of energy,
therefore heat is transferred by radaition, conduction and latent het.
·
Low
latitudes have a net surplus of energy
whereas high latitudes have a net deficit. Therefore poles are colder and the
equater is hotter.
Planetary
surface winds
·
Wind
is the horizontal movement of air on Earth’s
surface. It results from a difference in air pressure and a blow from high à low pressure.
·
As
air temp increases, air expands and rises = low pressure
Pressure gradient – the gradual change
in air pressure over an area
·
The
temp of winds is determined by its area of origin and surface which it has
travelled.
Atmospheric
pressure & winds
Atmospheric pressure
– pressure exerted by
weight od air in atmosphere at surface of the earth.
·
Units
of pressure = millibar (mb), measured by a barometer
·
Pressure
is at its greatest closest to the ground surface
·
Air
pressure decreases with altitude
·
High pressure occurs where air is desending and
is associated with dry weather
·
Low pressure occurs where air is rising usually in
wet and windy conditions.
Altitude – height of land above
sea level (m)
Latitude – angular distance a
place lies N or S of equator
General
atmospheric circulation system
·
Pattern
of wind and pressure belt within atmosphere
·
The
differential heating of Earth’s surface by the sun is sufficient to create
pattern of pressure cells
·
There
are 3 cells in each hemisphere = hadley, ferell and polar cells.
The
hadley cells
·
Two
Hadley cells; one in each hemisphere
·
They
form the basis of tropical air circulation and are responsible for seasonal
changes in climates
·
Each
hadley cell can be devided into 4:
Ø
Between
the 2 cells there is area of low pressure known as inter-tropical
convergence zone. Sun is hight in sky = ground heats in day =
evaporation, as hot air rises in convection
currents = area of low pressure developes. Rising cool air + H2O
vapour condenses = heavy rainfall.
Ø
At
high altitudes air moves polewards. Vsually
circulates as westerly winds as result of
deflection effect from rotation of earth = Coriolius
effect
Ø
Around
300 N+S, colder air at high altitudes sinks back to Earth’s surface.
As this air descends it warms and moisture evaporates. At surface, high
pressure is created know as subtropical
anticyclones.
Ø
As air reaches fround some air returns to equatorial areas as trade winds. The 2 trade winds move air towards
equator where it forms the ITCZ.
The
Ferrel and Polar Cells
·
Ferrel cells
occur at higher latitudes, responsible for
climate occuring in mid-latitudes
·
Air
on surface pulled towards poles = forms warm SW winds in N hemisphere and NW in
S hemisphere. As the winds travel they pick up moisture over oceans.
·
They
then meet cold air, drifted from poles.
·
Warm
aire from tropics = lighter than dense polar air so it rises as they meet.
Causing low pressure = mid-latitudes depressions. When it reaches the
troposhere some rising air returns to tropics as
part of Ferrel cell circulation, other is polewards as part of Polar
cell.
·
Surface
at N&S poles, desending air from polar cell = high pressure
·
In
N&S hemisphere winds are pulled from high pressure poles towards mid-low
pressure belt. Earth spinning on it axis = prevailialing surface winds to be
deflected to left in S and right in N hemisphere. Therefore cold air is
transported from high latitudes and warm air is brought in by Polar cell.
Helping to address energy deflict.
·
The
3-cell model does not allow for influence of depressions/anticyclones or high
level jet streams in redistribution of
energy.
Jet streams – a narrow belt of
fast-moving air near top of troposhere.
·
2
main locations of jet streams:
-
Polar front jet stream – a westerly band of wind. It marks the devision between the
Polar and Ferrel cells.
-
Sub-tropical jet stream – generally westerly, due to higher temperatures over land
than over the more southerly sea areas.
The 3-cell
model of atmosheric circulation
(Mid-latutude cell = ferrel cell)
Oceanic
circulation
·
Each
ocean has its own circular pattern of currents (= gyre)
produced as masses of H2O move from one climatic zone to another.
·
Set
in motion by prevailing serface winds
·
Direction
of H2O movement is deflected by Coriolis force
·
Particularly
dominant along western sides.
Map showing
oceanic circulation:
Latitude
Latitude – angular distance a
place lies N or S from equator
·
Length
of daylight hours in tropics has little seasonal difference, both day and night
are 12 hours
·
Summer at N &
S poles it never gets properly dark but in low winter it is 24 hours of
darkness
·
Due to latitude,
between equator and poles length of day and night vary.
·
The angle of
incidence – midday sun remains high in tropics all year round (rays are strong
and concentrated). Outside the tropics the angle of the sun is lower and rays
travel longer distance through atmosphere, losing energy. Sun’s energy is less
concentrated due to heating up larger area that tropics.
Altitude
Alititude – height of land above
sea level (m)
·
Temperature
decrease with height above sea level
·
Adiabatic lapse rate – temp change with height for parcel of air that has no
exchange of heat or moisture with surrounding air. Different types of lapse
rate:
-
In
atmosphere change of temp with height = environmental
lapse rate
è
Average
value = 6.5oC every 1000m
-
If
the air is dry its temp changes at the dry adiabatic
lapse rate (DALR)
è
10C
per 100m
-
Once
the air is saturated its temperature changes according to the saturated adiabtic lapes rate (SALR). Lower than
DALR because as air reaches 100% humidity, condensation releases atent heat,
taken to be 0.5oC per 100m.
http://www.youtube.com/watch?v=8BYWsmp9OY8
The Climate of the British Isles
The main influences on the climate of the British Isles are its latitude and its maritime position. It lies within the cool temperate western maritime climate belt. The weather of the British Isles is very unpredictable!
Temperature
- Mean summer temperatures in the UK are lower than average due to cooling influence of the Atlantic Ocean.
- In winter, average temperatures are above freezing due to the warming influence of the sea
Precipitation
- Precipitation is experienced throughout the year but varies with relief
- Upland areas rainfall can exceed 2,500mm annually; Lowland areas can be as little as 500mm
- Most rainfall is brought by the frontal systems moving west to east, releasing moisture as they cross the land
Wind
- Prevailing wind direction is southwest, governed by the general atmospheric circulation system
- Winds from the west can be strong and gales are common
- Winds are influenced by low-pressure weather systems, where rising air in the centre of the low results in a steep pressure gradient on the surface
Air Masses Affecting the British Isles
- Arctic: From the North; Cold temperatures and snow
- Polar Maritime: From the NorthWest; Cold, Moist weather
- Polar Continental: From the East; bitterly cold temperatures and possible snow
- Tropical Maritime: From SouthWest; mild and wet in winter, cool and moist in summer
- Tropical Continental: From SouthEast; summer only; brings hot, dry, heatwave conditions
Origin and Nature of Depressions
http://www.youtube.com/watch?v=DWhM2vbVdFM
Depressions are low-pressure weather systems
Characterisitcs:
- Low atmospheric pressure (below 1,000mb)
- Represented on weather map by system of closed isobars with pressure decreasing towards centre
- Move rapidly West to East across British Isles
- Isobars usually close together, steep pressure gradient
- Winds often strong and blow inwards in anticlockwise direction
Formation of a Depression
A depression affecting the British Isles originates in the North Atlantic where 2 different air masses meet along the polar front
The 2 air masses involved are:
- Polar Maritime Air (dense, moist and cold)
- Tropical Maritime Air (light, moist and warm)
As the 2 bodies of air move towards each other the warmer (less dense) air from the South rises above the colder (dense) air from the North.
The rising air is removed by jet streams but as it rises the Earth's rotational spin causes it to twist which prodeces a wave at ground level in the polar front. When it increases in size it forms a depression.
2 parts of the original front have now developed:
- warm front at the leading edge (warm air rises over colder air ahead)
- cold front at the rear where cold air pushes against the warm air ahead
In between the 2 fronts lies the
warm sector (area of warm and moist air)
As the depression moves
east the cold front gradually overtakes the warm front to form an
occlusion.
Weather Conditions
Weather conditions associated with a depression depend on whether the area has polar maritime or tropical maritime air over it.
- Polar brings average temperatures for season in winter but cooler temperatures for summer
- Tropical brings humid and mild winters and warm temperatures in summer
Origin and Nature of Anticyclones
http://www.youtube.com/watch?v=pm457OdgdnQ
Anticyclones have the following characteristics:
- Areas of relatively high atmospheric pressure
- Represented on a weather map by closed isobars with pressure increasing towards the centre
- They move slowly or may remain stationary over an area
- The air in the anticyclone subsides, warming as it falls, leading to a lack of clouds and dry conditions
- Isobars usually far apart so little pressure difference
- Weak winds, flowing gently in a clockwise direction in the North and anticlockwise in the South
Associated weather conditions in winter and summer
Winter anticyclones result in:
- cold daytime temperatures (below freezing to 5 degrees)
- very cold night time temperatures (below freezing with frosts)
- generally clear skies
- high levels of atmospheric pollution in urban areas which may be trapped by a temperature inversion
Summer anticyclones result in:
- hot daytime temperatures (above 25 degrees)
- warm night-time temperatures (may not fall below 15 degrees)
- generally clear skies
- hazy sunshine; early morning mists; heavy dew
- thunderstorms may occur
Fogs
Common features of anticyclonic conditions, it is basically cloud at ground level which restricts visibility to less than 1km.
Radiation Fog
- Forms under clear night skies when a moist atmosphere cools through the radiation of heat from the ground surface
- Common in winter due to long hours of darkness allowing maximum cooling
- Common under temperature inversions
Advection Fog
- Forms when a mass of relatively warm air moves horizontally across a cooler surface , the air is cooled to its dew point and then condensation occurs
- Most common arounds coasts and over the sea in summer
Storm Events
Atmosphere processes
Gales are common and generally are at their worst during autum as the sea temperature is warm enough to fuel powerful low-pressure cells.
The magnitude of gales is greatest in the exposed western coastal ares of the UK
Gales are associted with low-pressure weatehr systems and occur where there is a steep pressure gradient
Severe gales occur when the air pressure drops to a very low level.
Impact
The
Beaufort scale can be used to categorise wind strenght.
Every year gales are expected to result in short-term disruption to transport and power supplies, but such damage is usually minor.
Tropical Climates
The Inter-Tropical Convergence Zone (ITCZ)
ITCZ – a zone of rapidly rising
air and corresponding intense low pressure
·
Associated with an area of precipitation
·
Largely (but not entirely) determined by the
position of the overhand sun
·
ITCZ also represents the convergence (meeting point) of the two Hadley cells
Movement of the ITCZ
Video showing CNN's Mari Ramos describing the weather
pattern that might have contributed to Air France Flight 447's disappearance
Equatorial climate
·
Occurs in lowland
areas within 5-10o latitude of the equator and is sometimes
referred as the tropical rainy climate
·
Little variation in
length of daylight hours throughout the year because sun is never far from its
zenith.
·
Annual temperature range
is small – mean monthly temperatures 26-28oC
è With
high humidity and constant temperatures the climate cam be oppressive
·
Constant uplift of warm,
unstable air is caused by the convergence of tropical air masses in
these latitudes and results in low pressure throughout
the year.
·
Convection currents develop and produce cumulus clouds in the morningà build up in the afternoon
to produce cumulonimbus clouds à heavy
rain develops late afternoon early evening
Tropical wet and dry climate
·
Also known as the tropical
continental climate
·
Found polewards of
the equatorial climate generally between latitudes 5o and 15o
north and south of the equator
·
Latitude increases
so does the length of dry season à gradual transition from the
equatorial climate to the tropical wet and dry climate
·
Hot wet season à temps above 26oc
and heavy convectional rain
- Occurs
when the ITCZ moves polewards with the
overhead sun, causing low pressure to
develop and producing strong convection and heavy
rainfall.
·
Rest of the year = dry
season where high pressure dominates
- Double peak in temperatures coinciding with the sun
being directly overhead
- Corresponds
to a period when offshore trade winds blow
across the area from a dry interior source.
- Trade
winds are steady and strong and are created as air is pulled towards the low pressure around the ITCZ.
Tropical monsoon climate
·
Marked by distinct wet
& dry seasons
·
Monsoon:
associated with the seasonal reversal in wind direction
·
Himalayas =
major influence as they interfere with the general circulation of the
atmosphere
·
Seasonal contrasts in temperature between
land masses & oceans due to their different
heating capacities
·
June:
- ITCZ
moves polewards (towards Tropic of Cancer)
- Winds
blow SW = low pressure = warm, moist air
from Indian Ocean = heavy rain
·
January:
- ITCZ
moves S over equator
- Winds
blow NE = dry conditions = high pressure
& sinking air
Tropical revolving storms
Tropical revolving storms – intense
low-pressure weather systems that can develop in the tropics
·
Usually measure 200-700km
in diameter
·
Begins with low pressure
·
Several conditions must be present:
- Oceanic location +27oC (source of heat)
- Ocean depth at least 70m (provides latent heat)
- Location
at least 5o N or S of equator (Coriolis
Force can bring max rotation of air)
- Low-level convergence of air in upper atmospheric
circulation
·
Exists while there is a supply of latent heat & moisture = provides energy &
low frictional drag on ocean surface
·
As system reaches maturity, central eye
develops:
- Area
10-59km diameter
- Calm
- Clear skies
- Higher temperatures
- Descending air
- Wind
speeds +300kmh-1
The
structure of a tropical revolving storm:
Video explain tropical storms:
Distribution
·
Occur between latitudes 5o + 20o
N+S of equator
·
Tend to move westwards + at most destructive
Distribution of tropical
storms:
Magnitude + Frequency
·
Measured on the saffir-simpson scale (5
levels based on: central pressure, wind speed, storm surge & damage
potential)
·
Average lifespan of 7-14 days
Impacts
·
Vulnerability of people depends upon a range
of human and physical factors.
·
Main physical factors include:
- Intensity
of the storm
- Speed
of movement
- Distance
from sea
- Physical
geography of the coastal area
·
Human factors:
- Preparedness
·
Several ways in which tropical cyclones pose
a hazard to people and the built environment:
- Winds
- Heavy rainfall
- Storm surges
Prediction
·
Depends on the monitoring and warning systems
available
·
High economical cost associated with
evacuation
·
False alarms can cause complacency and people
refuse future advice
·
Developing countries, whose communications
are not so advanced as those in developed countries, may not be as well
prepared leading to a higher death toll.
Song about Hurricanes and Twisters:
Climate on a local scale: Urban Climates
Cities create their own climate and weather, this can
also be known as the ‘climatic dome’, within which the weather is different
from that of the surrounding rural areas.
Temperatures:
Urban Heat Islands
Urban heat island is
a warm spot in the ‘sea’ of surrounding cooler rural air; cities tend to be
warmer than rural areas due to:
·
Building materials e.g. tarmac, act like bare
rock surfaces, absorbing large quantities of heat during the day and then
slowly released at night
·
Heat comes from industries, buildings and
vehicles, which all burn fuel. Air conditioning units release hot air into the
atmosphere and people generate heat
·
Air pollution from industries and vehicles
increases cloud cover and create a ‘pollution dome’
Changes Over Time
The heat island effect is greatest under calm, high-pressure conditions and also they form better in the winter months where there is a bigger impact from the city heating systems.
Urban-rural contrasts are much more distinct at night when insolation is absent and surfaces that absorbed heat during the day slowly release it during the night
Changes Over Space
Temperatures usually change abruptly at the rural-urban boundary.
Temperatures rise steadily to peak in the city centre, on average the temperature rise tends to be 2 to 4 degrees per km.
In winter rural areas tend to hold snow for longer and have a greater albedo. (albedo = amount of solar radiation reflected back into the atmosphere by the Earth's surface)
Precipitation
Some evidence suggests that rainfall is greatest over urabn areas than rural areas, due to higher urban temperatures which causes low pressure to form over cities. Convection rainfall tends to be heavier and more frequent along with the incidence of thunder and lightning.
Fog
- In cities the occurrence of fog increases with industrialisation
- In the UK the Clean Air Acts of the 1950s resulted in a dramatic reduction in smoke production and particulate emissions and a decrease in the number of foggy days
Thunderstorms
- Thunderstorms develop under hot humid air
- Thunderstorms are characterised by violent and heavy precipitation
- Thunderstorms are produced by convectional uplift under conditions of extreme instability
- The updraft of air through the central area of cold clouds causes rapid cooling and condensation which leads to the formation of water droplets, hail and ice
- During condensation, latent heat is released
- As raindrops are split in the updraftitive electric charge builds up in the cloud, when the charge is high enough to overcome resistance a discharge occurs to areas of negative charge in the cloud or to Earth (basically it produces lightening)
- The extreme temperatures cause a rapid expansion of the air which develops a shockwave (simply this is heard as thunder)
http://www.youtube.com/watch?v=eYZaRYKHHvU
Air Quality
Particulate pollution and photochemical smog
As you may already have been able to work out air quality is poorer in urban areas than rural areas. The main pollutants are:
- Suspended particulate matter: responsible for fog, respiratory problems
- Sulphur dioxide: produces haze, acid rain, respiratory problems
- Oxides of nitrogen: cause accelerated weathering of buildings, respiratory problems, acid rain
- Carbon monoxide: associated with heart problems, headaches and fatigue
- Photochemical oxidants: associated with smog, damage to plants. eye irritation, chest pains
A mixture of fog and smoke particulates produces smog. Prominent in the first half of the 20th century due to high incidence of coal burning.
Recently there has been an increase in photochemical smog.
http://www.youtube.com/watch?v=2WF2aMbAcNc
please now see case studies of Beijing and Los Angeles!
Pollution Reduction Policies
Clean Air Acts
- The act of 1956 introduced smoke-free zones in urban areas
- Local councils are now required to monitor pollution and establish Air Quality Management Areas where levels are likely to be exceeded
Vehicle control in inner Urban Areas
- Many British towns and cities have pedestrianised CBDs and promoted Park and Ride services
More Public Transport
- Attempts have been made to persuade people to use public transport instead of cars
- Introduction of bus-only lanes, car-sharing schemes and tram systems
Zoning of Industry
- Planning legislation has forced companies to build higher factory chimneys to emit pollutants above the inversion layer
Vehicle Emissions Legislation
- Vehicle manufacturers have been made to develop more efficient fuel-burning engines and introduce catalytic converters or to switch to lead-free petrol
Winds
3 types of effects that urban structures have on wind speed, direction and frequency:
- Surface areas of cities is uneven due to varying heights of buildings (average wind speeds are lower in cities than surrounding areas)
- High-rise buildings may slow air movement but also channel air inbetween them
- Calm, clear nights there is a surface inflow from the cooler areas outside the city to the warmer areas in the city centre.
- Wind is therefore affected by the size and shape of buildings
In urban areas the annual mean wind speed is 20-30% decreased
With calms up 5-20%
Extreme gusts down 10-20%
Global Climate Change
Evidence for Climate Change
Pollen Analysis
- Helps scientists reconstruct vegetation from the past
- Used to estimate past climates
- Large temperature changes marked by clear changes in types of pollen
Dendrochronology
- Study of the links between the tree growth and climate
- Involves looking at annual tree rings
- wet and warm years = wide rings
- cold years = narrower rings
Ice-Core Analysis
- Allows scientists to infer temperature trends going back 400,000 years
- Testing for types of snow and amount of oxygen in it
- Taken from holes 2,000m in length from glaciers in Greenland and Antartica
Sea-Floor Analysis
- As an organism dies they collect on the ocean floor
- Analysing oranisms show surface of the ocean (e.g. amount of salt in the water)
Changing Sea Levels
- Risen on average 1.8mm per year and 3mm per year in the last 10 years
Historical Records
- E.G. Ancient writings, Government reports
- Provides useful supporting evidence for trends identified using other methods
- Describe characteristics of weather and climate
- Records show cave paintings of elephants in the Sahara
Instrumental Readings
- Recording stations not widespread or reliably calibrated/operated
- Use of a thermometer goes back to 1850
- Slight variations due to inaccuracies
Possible Causes of Climate Change
The Enhanced Greenhouse Effect
http://www.youtube.com/watch?v=CxUK2TizQ4g&feature=related
- Occur as human activity increases the ability of the Earths atmosphere to absorb radiation and increase temperature
- Due to human activities releasing more greenhouse gases
- Evidence is of increased levels of carbon dioxide
Variations in Solar Energy
- Evidence unspot activity may affect climate
- Times of high annual temperaures correspond to maximum periods of sunspot activity
Astonomical relationships between sun and earth
- Evidence to support changes in Earths orbit accounting for change in the amount of solar radiation reaching Earths surface
Changes in Oceanic Circulation
- Changes effect exchange of heat between ocean and the atmosphere
- Both can have long-term effects on World climate
Meteorites
- Meteorites colliding with Earth 65million years ago seem to have caused a decrease in incoming radiation depletion of the ozone and decrease global temperature whilst increasing acid rain
Volcanic Activity
- E.G. Krakatoa decreasing 0.5 degree
- World temperatures decrease after large eruptions
- After a series of eruptions there is increased dust particles which absorb incoming radiation
Plate Tectonics
- Effects may result from land masses moving to different latitudes or sea bed pushing up to form fold mountains
- Fols mountains lead to decreased temperatures
Composition of the Atmosphere
- Gases in the atmosphere can be increased following volcanic eruptions
- Growing concern over the increase in carbon dioxide in the atmosphere and a greenhouse effect is the result
Effects of Global Warming
Rising Sea Levels
- 21st century predicted 5-10cm per decade
- This could cause serious coastal areas and increaing erosion
- Huge cost for flooding defences
Climatic Change
- Warmer 2030 estimate 2degree temperature rise
- Continental areas could have a decrease in rainfall (good for agriculture)
- Widespread effect on vegetation, wildlife and agriculture
- Could be a decrease of food for some populations causing mass migration
Increase of Extreme Events
- Heatwaves, floods, droughts and storms last longer with increased intensity
- Increased evaporation over oceans and greater global precipitation
Bangladesh Monsoons
- Population in 2008 estimated at 150million
- High population density of 1,102 per km2
- One of the poorest countries so very ill-prepared
- Predicted effects:
- Increased average temperature of 15-20 degrees by 2050
- Increase of 10-15% of annual precipitation by 2050
- Increased intensity and frequency of cyclones during the wet season
- 20% increase in river discharge
- Significant rise in sea level on coasts (meaning 15% of land would be innundated with salt water)
- 13-30million people could be displaced from homes by permanent flooding
- Total annual rice crop decrease by 30% due to loss of land causing mass migration
- International tensions due to predicted mass migration
- Damage to coral reefs caused by storms
Effects on The British Isles
Coastal Regions
- Increase in mean sea level and frequency of storms would lead to more frequent flooding
Agriculture
- Higher temperatures would decrease the yield of cereal crops
- Pests could become more prevalent
- Increased length of growing season
- More opportunities to introduce new crop varieties
- Change in types of vegetation
Flora, Fauna and Landscape
- Lead to species movement
- Loss of native species
- Increased invasion by alien pests, weeds, diseases
- Increased competition from foreign species
Soils
- Reduced water holding capactiy, increasing soil moisture deficit
- Stability of building foundations affected
Water Resources
- Benefit from wetter winters
- Summer would cause greater pressure on water resources but also greater demand for water
- Effects on the hydrological cycle:
- Increased air temperature which would increase evapotranspiration
- Increased rainfall will increase flood risk, increased snowmelt
Energy Use
- Increased temperatures would lead to less space heating demands but increased demands for air comditioning units (this could lead to higher electricity use)
- Could increase in amount of renewable energy
Responses to Global Warming
International Responses
Carbon Dioxide has an effective lifespan of about 100years in the atmosphere
- 1992 Earth Summit in Rio de Janeiro developed countries agreed to stabilise carbon dioxide emissions
- 1997 follow up meeting in Kyoto, Japan over 100 governments signed a Climate Change Protocol which set specific targets for pollution. Most governments agreed by 2010 they should have reduced their atmospheric pollution level to those of 1990
- Kyoto agreement will expire in 2012 please NOTE:
- Some countries are already polluting at levels significantly above those of 1990
- Some countries are disproportionately responsible for releasing greenhouse gases
- Some countries, particularly LEDCs release low levels of greenhouse gases
Carbon Cedits
- Introduced after Koyoto meeting hereby each country has a set annual carbon dioxide pollution limit (major polluters can buy 'carbon credits' from less polluting countries
- If countries go over their limitoptions might be:
- Fines
- Investment in ways to reduce domestic carbon dioxide emissions
- Paying for improved technologies in other countries or for other countries to plant trees
Critics argue with this system because it serves the interests of the developed countries
In the UK one result of the carbon credit system is:
- The introduction of the Climate Change Levy - a tax on energy used by industy, commerce and the public sector
Post Koyoto
- July 2005 G8 world leaders attended a conference in Scotland where they agreed urgent action was needed to be taken in order to make significant reductions in greenhouse gases
- The Gleneagles Action Plan included plans to:
- Increase energy efficient buildings
- Cleaner fuels
- Renewable energy
National Responses: the UK
- 2006 Climate Change Programme set out to address issue of climate change
- Strategies included:
- Building regulations tightened to ensure new housing was properly insulated and had energy-saving boilers
- Transport - ensure financial incentives for those driving vehicles with low carbon emissions
- Carbon Trust - granted £65million over 5 years to provide small loans for small businesses investing in improved energy efficiency
- Scotland Woodland Creation - sponsored and designed to reduce nitrous oxide emissions from fertilisers
- Climate Change and Sustainable Energy Act 2006 - Department for Environment, Farming and Rural Affairs ha to report annuallu on levels of emissions of greenhouse gases
- Climate Change Bill 2008 - setting ambitious targets for reduction in emissions;ual review of initial targets set by the independant committee on Climate Change; Creation of 5-year carbon budget and creation of 5-year carbon budgets
Local Responses
- Sustainable development has become a key concept today
- To maintain current standards of living society needs to use resources more wisely
- Individual households can:
- Insulation - use cavity wall insulation, double glazing
- Recycling - Local councils have recycling targets
- Using energy wisely - Cut energy bills by turning off lights, turning down central heating, energy efficient light bulbs
- Using public transport - car-sharing, walking, cycling
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