STRUCTURE OF THE ATMOSPHERE

Troposphere | Closest to the earth and most weather happens here. Temperature drops as you go higher. Wind speeds increase. Most unstable layer. End of the sphere is marked by the tropoPAUSE- an isothermal layer where temp remains constant. | Stratosphere | Steady increase in temperature. Marked by the STRATOPAUSE. Atmosphere is thinner here. | Mesosphere | Temperature decreases to -90. No water vapour or dust to absorb radiation. Very strong winds at 3000 km/hr. MESOPAUSE | Thermosphere | Increase in temperature from the absorption of UV radiation |

Greatest amount of energy coming into the atmosphere is from insolation (short wave solar radiation). The amount of this energy from the sun is determined by:
*Solar constant- varies slightly & affects longer term climate rather than short term
*Distance from the sun- Earth’s orbit around sun can cause variation in distant
*Altitude of the sun in the sky- equator receives more energy as rays are head on. At 60 degrees N or S its at an angle so there’s twice the area to heat up & more atmosphere to pass through
*Length of the day & night

Some radiation is absorbed by ozone, water vapour, co2, ice particles, and dust reduce the amount reaching Earth. & clouds also reflect radiation back! ALBEDO is the ratio between the amount of incoming and reflected radiation. (Usually at 4%)
Short wave radiation is converted to heat and heats the surface of earth, while longer radiation (infrared) is radiated back into atmosphere. Longer wave tends to get trapped while short actually penetrates atmosphere easier.
THE ATMOSPHERIC HEAT BUDGET

THE HEAT BUDGET
The earth is not heating up or cooling down as there is a balance between incoming insolation and outgoing terrestrial radiation. But there are significant variations within the atmosphere. So although energy is lost through radiation throughout the atmosphere the net gain in radiation is not experienced in the Polar Regions, instead there is a net deficit between incoming and outgoing radiation. At lower latitudes between 40 and 35 degrees there is a net surplus of radiation (positive heat balance) This imbalance is rectified by heat transfers.

FACTORS AFFECTING INSOLATION AND THE HEATING OF THE ATMOSPHERE:

Longer term effects:
1) Altitude of the land- insolation heats the surface of the land which warms the air above by conduction & convection. As higher land is further away from heat source, the main mass of land heated by insolation is cooler. Density of air decreases with height adding to cooler effect. 6.4 degrees per 1000m. If temp increase with height it is a temp inversion.

2) Altitude of the sun- At higher latitudes the heat energy from sun has to pass through more atmospheres so more heat energy is lost to absorption or scattering.

3) Proportion of land & sea- land and sea react differently to insolation. Land heats up quicker than sea. Water has a greater specific heat capacity which means it requires twice as much energy to raise 1kg of water by 1 degree than it does for land. But oceans retain heat for longer.

4) Prevailing winds: As the temperature of an air mass is determined by the area which it originated from and the surfaces it passes over wind from the sea is cooler in summer and warmer in winter, than wind that has travelled over land.

5) Ocean Currents: Surface ocean currents are caused by influence of prevailing winds blowing across the sea. Warmer ocean currents migrate pole wards, away from the equator & colder currents replace them by moving towards equator in a circulatory motion known as a gyre. Clockwise in N hemisphere and anticlockwise in S hemisphere. The rotation of the Earth causes water to move westwards. North eastwards movement of warmer waters is a key factor in raising air temp that deliver mild winters and cool summers to Britain. Labrador Current off the N E of N America can reduce summer temps.
HEAT TRANSFERS THAT TAKE PLACE:
1) Horizontal Heat Transfers: 80% of the heat transferred away from the tropics is carried by the winds in the jet stream, hurricanes and depressions. The rest is transferred by movement of warmer ocean currents towards the poles.

2) Vertical heat transfers: radiation transferred by radiation conduction and convection. Latent heat also helps. For example additional energy is required to change ocean into vapour which rises condenses as water droplets e.g. as a cloud. Precipitation will release energy and warm the UPPER atmosphere. This vertical motion transfer’s heat from areas of positive heat budget by cooling as it rises to help transfer warm air to the poles.

6) Ocean Conveyor belt: The transfer of cold water at depth of Polar Regions to the equator is like a conveyor belt. As water cools at the poles the formation of ice, leaves the remaining water- saltier and denser. Denser water sinks. It sweeps the Antarctic continent. These motions are reciprocated by movement of the less salty and less dense surface temp which moves north towards N Atlantic from India & pacific oceans. These warmer waters have a significant effect on temp of N Atlantic. North Atlantic is warmer than North Pacific.

Short Term Factors:

1) Seasonal Changes- Insolation is distributed equally in each hemisphere at the spring (21st March) and Autumn (22nd September) equinoxes, when the sun is at the equator. In the summer around 21st June and winter around 22nd December 22nd solstices when the sun is directly overhead at the tropics, maximum insolation is experienced in the N hemisphere and the S hemisphere respectively.

2)Diurnal Range- the length of day & night varies in all locations away from the equator. At the poles there is no insolation during winter months when the regions are tilted away from the sun and there are up to 24 hours of daylight in summer when they are tilted towards the sun.

3) Local
*Aspect- slopes alter the angel at which the sun strikes Earth. South facing slopes in the N hemisphere receive more of the available insolation than N facing. This has impact on agriculture.

*Cloud cover- clouds may reflect, absorb and scatter incoming radiation, but can also act as an insulating blanket, keeping the heat in the lower atmosphere. Therefore when there are clear days temperatures rise more rapidly as more insolation reaches the surface but when there are clear nights they fall quickly as terrestrial radiation reduces the surface temp. Conversely when it is cloudy temperatures do not rise as high or fall as low.

*Urbanisation – Urban surfaces tend to absorb more heat than natural surfaces during the day and radiate more at night creating urban heat island effects.

KEY DEFINITION:
Coriolis Force: an effect that causes anybody that moves freely with respect to the rotating earth to veer to the right in the N hemisphere and the left in the S hemisphere.

Position of the ITCZ:
Changes according to the seasons. The sun is located directly above the TROPIC OF CANCER on 21st June which pulls the ITCZ North of the Equator whereas on the 21st December it is just over TROPIC OF CAPRICORN and the ITCZ moves into Southern Hemisphere.

FRONT (Definition): Boundary between a warm air mass and cold air mass results in frontal rainfall.
The ITCZ shifts N and S each year. It is in reality not a continuous belt of cloud & rain. Can be known as inter tropical discontinuity. Hot air rises in ITCZ becomes cooler and condenses leading to cumulonimbus clouds to form which brings heavy rainfall! Air cools to the point that the density differences cause it to move pole wards. In the N hemisphere air circulates as upper westerly winds and is deflected by Coriolis force. At around 30 degrees N and S cooler air starts to sink to surface. As it descends it creates high pressure beneath and cause’ it’s warm at the same time it holds a lot of moisture, so this area of high pressure and clear skies are called SUBTROPICAL ANTICYLONES. At ground level some returns to equator as trade winds, which are deflected by Coriolis force again to the right in N and left in S. Wind @ ITCZ known as doldrums (light winds) . Remaining air travels towards poles forming S westerly’s in N hemisphere. They pick up moisture when they cross ocean and responsible for bringing wet weather. When these winds meet the colder air of the Arctic @ polar front they rise and form the boundary between the Ferrell and polar cells. Area of warmer unstable air is associated with mid latitude depressions & heavy rainfall.
ITCZ- inter tropical convergence zone: result of the heating of part of the Earth’s surface caused by concentrated insolation. Hot air rises. This draws in cooler air that flows across the surface to replace rising air. Air streams are drawn in from N and S where they meet.
Horizontal air movement is known as wind. But it can move vertically too. Winds are caused by differences in air pressure. They move from high to low. Air pressure decreases with increasing height. When air temperature increases it becomes warmer and less dense and will rise, leaving low pressure beneath. Isobars which are close together show high pressure.

In the North Hemisphere wind blows anticlockwise into a low pressure zone and clockwise outwards away from a centre of high pressure as a result of the effects of the Coriolis force & friction.

Coriolis force is the deflection of winds due to the rotation of the Earth. Deflects winds right in the N hemis and left in the South hemis. In mid latitudes & in the mid troposphere the pressure gradient of coriolis force are in balance and winds do not move from high to low pressure so much as between them. This is called geotropic wind. Friction from the Earth’s surface reduces the Coriolis Effect. At higher altitudes frictional forces are reduced and the effect of the pressure gradient dominates.

WIND:
Most common direction of wind is the South West but this is variable from day to day & winds from other directions are quite frequent. With long spells of easterly or north easterly not unusual in winter. Strongest winds are found in West and North of the country as these areas face the prevailing SW winds. Wind speed increases with height so mountains experience higher wind speeds.
A gale is defined as: wind speed of over 63 km/hr for a duration of at least 10 minutes.
PRECIPITATION:
North & West of the British Isles shows greater rain. The key factors affecting this pattern are the direction of the prevailing winds and altitude.

Relief rainfall occurs when moist air that has been travelling over the sea is forced to rise over upland areas. As it rises and cools, the air reaches dew point (saturated) and condensation occurs leading to rainfall.

In areas such as Keswick in the Lake District rainfall averages around 1500mm per year where as Tynemouth at similar latitude on the east only receives 660mm of rain falls. This is due to the RAIN SHADOW as air that has lost a lot of moisture over the hills will sink back down, warm up, and as warmer air can hold more moisture it is less likely to generate rainfall.

Britain is affected by FRONTAL RAINFALL:
This occurs when warmer air is pushed up over a wedge of cooler air where two air masses meet in a frontal system. This occurs where cooler polar air undercuts warmer tropical air. As the warmer air is forced to rise it cools, water vapour condenses and forms cloud and rain over a wide area. Especially in winter months when successive low pressure systems or depressions approach the western shores of Britain.

CONVENCTIONAL RAINFALL:
Rainfall due to extreme localised heating of the ground. (Summer months). Occurs when air above ground is warmed becomes less dense than the surrounding air & rises. When it reaches dew point condensation occurs & clouds develop but very strong heating produces highly unstable air which continues to rise creating cumulonimbus clouds. Creates intense sudden rainfall affecting South East Britain especially.
TEMPERATURE:
Temperatures reduce towards the north due to the reduction in amount of isolation at higher latitudes. Places further from the sea experience higher summer temperatures, on average as the cooler temps from the sea have less influence inland. In larger land masses this is referred to as ‘contintentatilty’ but is evident in the UK.
Areas as higher altitudes are cooler as temperatures drop by 6.4 degrees for every 1000m increase.
The effect of prevailing winds and oceanic currents are evident in the higher winter temperatures in the land bordering the Irish Sea as warmer air associated with the North Atlantic Drift brings warmer Gulf Stream waters to Western Britain. CLIMATE OF THE BRITISH ISLES:

Depressions are characterized by passage of low pressure air. Anticyclones are characterized by high pressure.
The air that descends from the upper atmosphere is cooler, drier and denser than air at ground level. As it descends it warms and can hold a lot of moisture leading to limited condensation and reduced rain. This stable air can cover several thousand KM and presents a gentle pressure gradient with weak winds blowing clockwise out from the centre of the high pressure area. The passage of anticyclones tends to be much slower than depressions. Weather can be days or weeks depending on the season.

WINTER ANTICYCLONES:
When the sun is low in the sky during the winter months & less isolation is available to warm the British Isles, the clear skies of a high pressure zone mean that the moderate gain of warmth during the day can be more than offset by rapid loss of heat at night. Surface cooling frequently gives rise to radiation fog and frost which may persist because of the weak sunshine during the day. When dry cold polar continental air from central Asia and Europe moves across the North Sea it can bring heavy snowfall to eastern regions. Where blocking anticylonic cells exist for days over Europe the deflection of warmer depressions away from Britain can bring dry freezing conditions. These can produce a low sharp temperature inversion leading to persistent cloud, sometimes known as a anticylonic gloom.
SUMMER ANTICYCLONES:
These are characterized by clear skies which allow maximum isolation producing temperatures of over 25 during the day time. Radiation lost at night can lead to short lived temperature inversion and the formation of dew & mist which clear quickly in the morning. Onshore winds along the east coast produce advection fog.
ADVEC TION fog occurs when warm air moves across cooler surface such as the North Sea. Major anticyclones over Britain & NW Europe can deflect low pressure areas to the North reducing the likely hood of a cooler wetter air in summer. If this persists it could create a heat wave especially if the air has originated from Tropical Continental such as North Africa.

This storm evaded normal weather prediction services as it became unexpectedly severe during the night of the 16th October.
The depression resulted from the mixing of very warm tropical continental air from North African and colder air from the North Atlantic & in part originated during the aftermath of Hurricane Floyd along the East coast of the US.
CASE STUDY: THE GREAT STORM OF 1987

RESPONSES:
*Clear up took considerable time with emergency crews being drafted in from Northern regions where damage had been more slight.
*Losses from storm totalled £1.4 billion in the UK. 1 in 6 households in SE England submitted insurance claims.
*MET Office enquiry recommended that observational coverage of the atmosphere over the ocean to the S and W of the UK was improved by increasing the quality and quantity of observations along with refinements made to computer models used in forecasting.
*A significant clean up of fallen trees was criticised by ecologists for removing damaged broad leaf trees that would have recovered with time.
PREDICTION:
The storm of 1987 gained an almost mythical status as the storm that proved the weathers forecasters wrong. In reality this ‘1 in a 100 years’ event was very difficult to predict due to the speed of the drop in pressure. An evening weather forecast by the MET office correctly described the current state of the depression & its likely path. The veering of the storm to a more northerly track was noticed too late to allow for effective warning. Most people were asleep so wouldn’t have heard the additional warnings.
EFFECTS- the effect of the storm was lessened since it occurred at night so fewer people were about. But there were still other effects:
*16 People died
*many houses suffered damage to roofs & walls
*15m trees were uprooted
*ferry blown ashore
*communications were broken with trees falling on railway tracks and roads, and damage to power lines leading to blackouts.
It was tracked along the Bay Of Biscay but on the evening of 15th October it suddenly began to intensify and veered Northwards towards the mouth of the English channel. The deepening of the depression to 958mb was believed to be the result of a very strong jet stream and warming over the Bay of Biscay which together probably released latent heat energy warming the air even more and reducing pressure even further. The centre of the low pressure tracked over Britain for 6 hours during the night with extreme wind speeds being experienced on the South coast; with winds of up to 115km/hr gusting to 141km/hr were recorded at Dover.

Depressions begin in the North Atlantic where tropical maritime airs from the south and polar maritime air from the North meet.
The warmer less dense air rises and is removed by strong upper atmosphere winds (jet stream). This rising twisting vortex of air produces a wave form at sea level in the polar front which becomes more exaggerated as the wave form develops eventually becoming a depression.
The embryonic depression usually moves North East guided by the polar jet stream. As the low pressure zone develops in a mature depression the cold front advances more rapidly and more warm air is forced to rise. The resultant decrease in pressure creates a more pronounced pressure gradient and winds blow towards the centre with increasing strength. The effect of the Coriolis force means that these anticlockwise travelling winds come from SOUTH WEST. The warm rising air cools at altitude until dew point is reached and condensation produces cloud. As uplift continues cloud thickens and precipitation is initiated along the warm front. As the warm front passes there is a rise in temperature within the warm sector. This warmer air which is NOT being forced to rise as fast as the air at the warm front produces less cloud and rain is less likely. Some clear skies develop before the rapidly approaching cold front undercuts the warm sector and forcing warm air to rise. The steeper gradient of this front often creates thicker cloud and more intense rain. (Cumulonimbus clouds). In time the more rapidly travelling cold front catches up with warm front and undercuts it to raise the warm sector air above the surface. This OCCLUSION FRONT occurs first in the centre of the low and extends outwards. As cooler air begins to infill the depression there is less uplift of air. Reduction in condensation means there is less cloud and rain. Winds weaken and pressure gradient reduced and low pressure zone eradicated/

Tropical Revolving Storms:
TRS’s are slow moving systems of extreme low pressure. They are known as hurricanes, tropical cyclones and typhoons according to their location.

Common factors in genesis & development of TRS include:
*Warm tropical oceans (temp 27 degrees) at a depth of at least 50m. This is necessary to ensure sustained heating over a wide area which provides a heat source to create a large mass of warm unstable air.

*Occur in autumn as this is when the sea temps are at their highest. With temps having built up over summer.

*Found within trade wind belt as this is where the surface winds warm as they blow towards the equator

*They usually located between latitudes of 5-20 degrees N or S of equator.

*Travel westwards on UNPREDICTABLE courses.

*On landfall they move towards nearest poles.

*Away from their ocean heat source they rapidly lose power and become normal storms before they’re classified as depressions.

HURRICANES

How a depression develops into a storm:
The rising air currents must be maintained & that requires a constant supply of heat & moisture. As winds sweep over the ocean they increase the rate of evapotransporation. Moist air rises and condenses to form cloud & heavy rainfall, releasing latent heat and further driving the storm.

Once the storm has developed it eventually develops an ‘eye’ with a diameter of 30-50km wide. This area of subsiding air with light winds, clear skies and high temperatures. The descending air increases instability by warming and serves to increase intensity of the storm. Wind speeds of up to 160-300 km/hr. Associated with high winds are storm surges which are broad waves of water pushed ahead of the storm and exacerbated by the rise in sea level allowed by the intense low pressure beneath the hurricane.

Once hurricanes reach land they rapidly decline as they lose their energy. Also it if carries on moving away from the tropics the cool waters reduce its energy too.

Management
The national response plan indicates that initial response to a disaster is a local government responsibility until it’s resources are exhausted, then appeal may be made to county, state & then federal level. It appears that many of the problems arose from inadequate planning & communication systems.

*FEMA delivered supplies and refrigerated trucks to deal with the anticipated dead.
*Volunteers assisted people emerging from the storm, this carried on for 6 months after.
*58,000 National Guard personnel were activated to deal with after math with troops coming from all 50 states.
*Congress authorised $62.3 billion in aid
*FEMA aimed to provide 700,000 people with houses but only 1/5th of the trailers requested were supplied. They also paid for temp hotel costs of 12,000 individuals & families. By a year later in 2006 100,000 people were still living in trailers.

*International aid was significant with over 70 countries pledging monetary donations. Kuwait donated $500million. American Red Cross charities raised 4.25 billion from voluntary contributions.

Impact
Physical:
*Storm surges were predicted to rise the sea by 8m due to the low lying land along the Gulf Coast of the US this was dangerous so an evacuation was called for. Winds of 217km/hr caused 8.2m rise in sea levels. Rainfall of 200-250mm fell with 380mm being recorded.

*Mississippi river with already enhanced artificial levees broke in over 50 places flooding approx 80% of the greater New Orleans area. Breaches in the floodwalls defending the city were later estimated to be responsible for 70% flooding.

Social/Economic:
*3 million people had no electricity
*30 oil platforms were damaged in the Gulf & 9 oil refineries were closed reducing production up to 25%.
*5300km squared of forests were destroyed a loss of $5 billion for the forest industry.
*1 million people left the region with places like Chicago receiving an additional 6000 people. By 2006 200,000 had returned to New Orleans but it was still less than half its ‘pre’ Katrina population.
*insurance premiums rose and become unaffordable/lack of insurance.
*Floods damaged property and life causing $81 billion costs and 1836 deaths.

Environmental:
*Many areas suffered devastating coastal erosion. E.g. Dauphin Island was breached by storm & sand was transported across the barrier island into the Mississippi. This shifted the island landwards.

*560km squared of land in the Chaundeleur Islands became submerged by Katrina and later by Rita.
*Breeding grounds for marine mammals, migrating birds, turtles and fish were lost as about 20% of marshlands were inundated by seawater.
*During clean up, flood waters from New Orleans polluted with raw sewage and heavy metals, pesticides and nearly 25m litres of oil were pumped into Lake Pontchartrain.
FORMATION:
It formed over the Bahamas on the 23rd August.
It gained strength and was categorized as a tropical storm named Katrina on the 24th. It moved westwards and just before it made landfall at Florida it reached hurricane strength. The storm did weaken over land but it intensified to hurricane force over the warm waters of the Gulf of Mexico going from a category 3 to a category 5 on the saffir Simpson scale. The warm waters of the loop current helped to reduce pressure & raise winds even further. The hurricane reached it’s peak on the 28th August at a category 5 at 1pm. With max winds at 280km/hr. Katrina’s track was what caused the damage. It tracked over one of the most densely populated parts of the Gulf Coast of the US.
Although it had reduced in intensity when it made landfall in Louisiana on the 29th it was still a category 3. Moving northwards till it made it’s final landfall on the Louisiana/Mississippi border. (Cat 3) As it moved inland it rapidly lost intensity and became a category 1. By the 30th it became a tropical depression.
Where: New Orleans, Louisiana US.
When: August 2005 23rd-30th (late August)
Cost of damage: Over $80 billion
Deaths: 1,830 deaths

Air Quality: particulate pollution, photochemical smog & pollution reduction policies:
Air quality in urban areas is poorer than in rural. They experience 7x more dust particles in their local atmosphere. With 200 times more sulphur dioxide. 10 times more Nitrogen dioxide. 10 times more hydrocarbons, and 2x co2. These pollutants increase cloud cover & precipitation and cause photochemical SMOG, which brings higher temperatures and reduced sunlight.

Primary pollutants are substances directly emitted from a process such as CO from cars. Secondary is formed when pollutants interact e.g ground level ozone (Makes up smog). Some can be both primary and secondary.
Some primary pollutants include:
*Sulphur Oxides (SOx) – emitted from the burning of coal
*Nitrogen Oxides (NOx) – emitted from combustion (cars) causes brown haze
*CO – colourless non irritating poisonous gas. Incomplete combustion.
*CO2 – combustion
*Volatile organic compounds (VOCs)- hydrocarbon fuel vapours/solvents
*Particulate matter- is measures as smoke/dust. Particle matter (PM)
Precipitation: frequency & intensity, fogs, thunderstorm’s & their relationship to urban form & processes.

Key Definition: Evapotranspiration: The combined losses of moisture through evaporation & transpiration.

Air in the cities is usually warmer, therefore can hold more moisture. The lack of plants means evapotranspiration is reduced. Cities have thicker cloud than rural areas, as a result from convection currents. Higher levels of cloud explain why the precipitation is higher in urban areas than rural. (28% higher per month)
If snow falls in cities it sits on the ground for a shorter time than in rural areas. Fogs tend to be thicker and persist longer. It forms due to the condensation.

Temperatures: The Urban Heat Island Effect:
Concrete, brick and tarmac have a higher thermal capacity than natural surfaces enabling them to store heat during the day and release it slowly at night when the air around is cooling as a result of radiation loss. Central heating, traffic, fumes and even people contribute to higher temperatures.
Temperatures between urban and rural vary by 0.6 in the day and 3 or 4 degrees at night.
Climate on a local scale – Urban Climates

Microclimates involves studying a climate on a smaller scale. Temperatures in urban areas may differ from surrounding countryside for several reasons:
*Buildings tend to absorb more heat than natural surfaces and can store heat.
*They create additional particulate matter in the form of dust and other condensation nuclei which in turn affects the amount of sunlight that reaches the city
*They affect the amount of moisture in the air
*Tall buildings affect the way air moves across the city so wind velocity is reduced.

SMOG:
Is a mixture of smoke and fog. Occurs when smoke and SO2 mix.
London smog of 1952 formed when an anticyclone settled of Southern England & remained static. The Thames became prone to radiation fogs. The temp inversion trapped polluted air and a combination of dense fog and sooty black coal smoke produced dense persistent smog. The decrease in visibility caused an increase in crime and transport delays. 12,000 people were killed due to respiratory problems.

The effects of Urban structures and layout in wind speed direction and frequency:

Wind speed is reduced in cities by as much as 30% because there is increased frictional drag as the win is obstructed by buildings. Conversely very tall buildings can channel wind in between creating a canyon effect were winds are higher. This combined with turbulence can prove hazardous to people at street level.

UK Air Quality indicators for sustainable development:
The indicators for air quality & health provide two measures of how air quality has changed over time and include trends in ozone (O3) and particulate matter (PM10).

These two types of air pollutants are believed to have the most impact on health through long term exposure.

Since 1993 PM levels have overall decreased. (Urban). While rural ozone levels show no clear long term trend. Urban ozone levels have increased long term since 1993 mainly due to reduction in urban emissions of NOx which destroys ozone.
Pollution Reduction Policies:
DEFRA (Department for Environment Food & Rural Affairs) are responsible for local government and mainly targeted at air quality in cities. The UK national air quality info archives offer ‘real time’ monitoring of current air pollutants. Including:
*hourly mean ozone
*Hourly mean No2
*15 minute mean sulphur dioxide
*8 hour mean CO
*24 hour mean Particulate matter
PHOTOCHEMICAL SMOG:
This forms when sunlight hits various pollutants in the air and forms a mix of chemicals that can be very dangerous. A photochemical smog is the chemical reaction of sunlight NOx and VOCS which produces airborne particulate matter and ground level ozone. Associated with modern industry. More common in cities with sunny warm and dry climates e.g. LOS ANGELES –US.

The Earth has swung between cooler phases which have generated ice ages (glacial periods) and warmer periods when ice has retreated (interglacial). In between these phases there has tended to be an irregular transition between the two states which peaks and troughs in temperatures. Analyses of these fluctuations have suggested that an accelerated warming is taking place. (Global warming). The Earths temperatures have rose by 0.6 + 0.2 degrees during the 20th Century. Scientists believe this is due to human activity. Evidence for climatic change | Description | Glacial & post glacial deposits | Records of ice advancing during colder periods & retreating during warmer times. | Dendrochonology | Tree ring dating. Warm & wet years produce a thicker ring were cold drier years produce thinner rings. Can stretch back 10,000 years. | Sea Floor Analysis | Analysising microfossils, drilled from seep sea oozes provide climatic info. Isotopes of o2 and co2 provide complex info. E.g. the ratio of o18 and o16 is a good indicator of glacial phases. In warmer phases more o16 is released. | Ice Core Analysis | Goes back over 10,000 years. In colder periods less co2 is trapped in the ice. | Radiocarbon Dating | Using the isotope carbon 14. Carbon is taken in by plants during the carbon cycle. C14 decays at a known rate and its abundance is compared with c12 which does not decay. These ratios can help determine the age of plant remains up to 50,000 years. | Coleopteran Beetles | Looking at fluvial lacustrine and terrestrial sediments can help indicate the location of earlier climatic belts. | Shift in vegetation belts | Warming has allowed migration of species into areas. Supported by POLLEN ANALYSIS which shows what species were dominant at a given time. Pollen grains may be preserved in a peat bog. | Changes in sea level | Water released from melting ice caps. E.g the raised beaches in Arran Scotland. | Fossil landscapes | Such as the valleys of the Lake District or the granite tors of Dartmoor could not be produced under CURRENT climate. |

The image to the left shows the British Isles and Western mainland Europe. The red areas are at most risk of flooding due to rise in sea levels.

THE HOCKEY STICK DEBATE

Global Warming: Possible Effects:
- Temperature rise between 1.8-4 degrees but it could be up to 6.4 degrees.
-Sea levels likely to rise by 28-43cm
-Artic summer sea ice will disappear
-Increase in number of heat waves
-will lead to increase intensity of tropical storms.
Global warming: Possible causes:

There are debates as to whether or not the rising in global temperatures is due to human activity or just a natural occurrence. There are many interpretations of the graphs above. The ‘hockey stick’ shaped graph showing sustained temperatures for around 1000 years and then a sharp increase since around the 1800’s is seen by many as definite proof that we have had influence on the climate. Others have suggested that the data is questionable as accurate temperature recordings have only been present the past 150 years. Much is used from proxy sources such as tree rings, ice cores, lake sediments and historical records. But everyone agrees on one thing: That the build up of greenhouse gases will lead to several degrees of warming.

HOW ALL THIS WILL AFFECT THE BRITISH ISLES:
Apparently we could have a more Mediterranean climate. But in reality it’s likely to be a bit more varied as Britain’s climate is greatly affected by it’s location on the edge of Europe and the influence of the North Atlantic drift.
With summers set to rise by 3.5 degrees b y 2080 with the South and East of the UK most likely to see the largest temperature rise, in contrast to the North & West which will see the least. Precipitation will also increase. Summers will see less, winters more. Less snow will fall. A 60% decline in Scotland and 90% elsewhere.

EVIDENCE TO BACK THESE CHANGES UP:
* 4/5 of the warmest years have been recorded since the 1990’s.
*January-June 2002 was the warmest start to a year in the Northern Hemisphere
*1995 saw the most hot days in 225 years. There were 26 days above 20 degrees.

Higher temperatures could:
*Reduce water levels in soil leading to crops dying
*loss of native species
*longer growing season e.g. more grass for dairy & beef but cereals could be hit by drier summers
*increase in number of pests with milder winters
*reduce snow cover in Scotland leading to less tourism.

Wetter Winters could:
*benefit water supplies
*mean more deaths due to storms and flooding

Rise in sea level and increase in the frequency and magnitude of gales and storm surges could:
*result in more flooding especially around estuaries
*have a major impact on housing, industry, farming, energy, transport and wildlife.
Extreme Weather:
There have been links that global warming is increase the intensity and frequency of tornadoes and hurricanes. The warmer waters fuel the storms.
Severe Water shortages:
Reduced rainfall and the salination of groundwater in coastal zones as sea levels rise will reduce the amount of water available for drinking and irrigation putting millions of lives at risk.
Food Shortage & Disease:
Africa, the middle east & India are expected to experience huge reductions in cereal yields as a result from lack of rainfall. China & Central Asia will see an increase in risk of malaria.
Rising Sea Levels:
Sea levels have rose by 1.8mm per year from 1961 to 2003. Posing threat o the Netherlands and Bangladesh as well as smaller islands in the Indian & Pacific ocean. Even in the UK.
Ice Caps:
Global warming is responsible for the melting of the ice caps. More water will be released into the oceans. Without the cooling effect of the ice oceans will get warmer and keep expanding. The artic has lost 1.7 million km2 of ice since 1980. They could disappear by 2050 or even by 2013. The main worry is the amount of methane which will be released. Methane is a greenhouse gas which will add to the greenhouse effect.

RESPONSES TO GLOBAL WARMING:

International:
Using common policies to engage in cooperation between governments.

The Kyoto agreement:
Britain is signed up to this. It put limits on emissions to ensure the reduction of greenhouse gases. Adopted in 1997.
Russia agreed in November 2004.
US and Australia are a part of the treaty but have not managed to adhere to requirements thus failing to abide by the protocol.
UK is not on course to meeting the target of a 20% reduction by 2010. But they revised another target to reduce levels by 60% by 2050.
The Kyoto treaty expires in 2012 and talks began years ago on a future treaty to succeed the current one. Carbon Credits:
The aim is to allocate so much carbon usage to countries according to their apparent need. Aim is to cap emissions and the let the free market assign a value to any shortfall through trading. Credits can be exchanged between businesses or sold in a way that balances emissions.

ACTION IN THE UK:
The Eu emission trading system: (similar to carbon credits)

Key areas for action:
-Reducing co2 emissions from power stations before it;s released into the atmosphere.
-using sources of energy that generate less co2 such as nuclear/ solar/ wind/ wave
*reducing our demand for energy by using less in our industry, transport and homes.

Energy Production:
Most of UKs electricity comes from thermal power stations burning gas/coal/oil. Nuclear power stations are set to be cleaner in terms of greenhouse gases emissions but cost a great deal to build and the need to deal with their radioactive waste means they are more expensive.
Salt rich layers of rock beneath sea floor (saline aquifers) can trap co2 pumped down into them. As the momement dumping co2 is prohibited in the North Sea.

Local Responses
*Many citizens can access funding to reduce the amount of energy used in their homes or by improving insulation
*Recycling schemes now encourage re-use of most household waste including cans, plastics and bottles.
*Agriculture is responsible for about fifths of the world’s greenhouse emissions so emissions can be reduced by buying local food.
*Walking or cycling instead of using a car.
*Reduced use of air travel.
Renewable Energy:
*Wind power- clean sustainable and cheap. But many people don’t like seeing the turbines and looks unsightly.
*Geothermal power (heat from ground) is largely untapped. The heat energy stored is equivalent to 50,000 times the total energy stormed in all the world’s oil and gas.
*Ground source heat pumps are now available to pump this heat from below ground to warm individual homes.
*Chicken, pig and human excrement are all currently being used to generate electricity. The first UK generator using animal dung began in 2002.
*Biodiesel to run vehicles with far lower co2 can be made from most veg oils including soya bean. But the switch to bio fuel crops has affected world food supply and pushed up prices.