Geography Paper 1 earths life support systems

Why is water important

• Oceans is 71% of earths surface

• Oceans moderate temperature by absorbing heat, storing and releasing it

• Clouds reflect 1/5 of incoming solar radiation

• Water vapour absorbs long wave radiation

What is water used for?

• 65-95% of water in all living organisms

• Growth, Reproduction, Metabolic processes

• Photosynthesis, Respiration, Transpiration

• Plants need it for rigidity and xylem vessels to transport

• Its a medium for all chemical reactions

• Panting, evaporation, sweating cools organisms

• Generates electricity, crops, sewage, agriculture

• Drinking water

Why is carbon important?

• Common chemical element

• Stored in carbonate rocks

• Proteins, carbs, nucleic acids basic building blocks

• Fossil fuels, coal, oil and gas

• Oil used in manufacture of plastics/paint

Water cycle

• Closed system globally

• Open system at smaller scale

Stores of water

• Ocean 97%

• Ice 2%

• aquifers 0.7%

• Atmosphere 0.001%

• Land

Transfers of water

• Evaporation

• Transpiration

• Precipitation

Inputs of water to atmosphere

• Vapour evaporated from ocean, soil, lakes and rivers

• Vapour transpired through leaves

Outputs of water from atmosphere

• Precipitation

• Condensation(fog)

• Ablation(melting and sublimation)

Run-off

Meltwater drains from land into rivers/oceans

Percolate

Water into rocks or aquifers

Transfers of carbon

• Decomposition

• Respiration

• Photosynthesis

• Oxidation

• Weathering

• Volcanic activity

• Combustion

Stores of carbon

• Biomass (Biosphere)

• Soil (pedosphere)

• Rocks

• Sea floor

• Ocean (hydrosphere)

• Atmosphere

Slow carbon cycle

• Rocks, sediment, fossil fuels locked away for millions years

• CO2 diffuses from atmosphere into oceans where marine organisms make their shells and skeletons

• They fix dissolved carbon

• On death organisms sink and over millions years exert heat and pressure and convert into rock

• Takes around 150 mil years

• Some subduct into tectonic plates and come out in volcanic eruptions

• Other attacked by chemical weathering

Fast carbon cycle

• circulates rapidly between atmosphere, oceans, organisms and soil

• 10-1000x faster than slow carbon cycle

• Plants and phytoplankton are key

• Absorb CO2 through photosynthesis with water to make carbohydrates

• Respiration releases CO2

• Decomposition of dead organic material by microbial activity releases CO2

• Atmospheric CO2 dissolves ocean surface water and ocean ventilates CO2 back to atmosphere

• Carbon is stored in ocean by natural sequestration for about 350 yrs

Precipitation (of water)

• Water/ice that falls from clouds

• Rain, snow, hail, sleet, drizzle

• Forms when vapour cools to due point and condenses into droplets forming clouds

• Droplets aggregate and leave clouds

• Rain flows quickly into rivers

• Snow settles at high altitudes

What is intensity of rainfall?

The amount of precipitation falling in a given time

Transpiration

• Diffusion of water vapour to atmosphere from leaf pores (stomata)

• Influenced by temperature and wind

• Influenced by water availability in plants

Condensation

• When vapour turns to liquid water

• Happens when air cooled to due point

• At critical temp air is saturated with vapour and becomes condensation

• Condensation near the ground produces dew and fog

Cumuliform Clouds

• Flat base

• Form when air heated through contact with earths surface

• Causes convection and cooling

Stratiform Clouds

• Have layers

• Form when air moves horizontal across a cooler surface (advection)

Cirrus Clouds

• Form at high altitude

• Have tiny ice crystals but don’t form precipitate

Environmental lapse rate

Vertical temperature profile of lower atmosphere at a given time

Dry adiabatic lapse rate

The rate at which a parcel of dry air cools

Saturated adiabatic lapse rate

Rate at which a saturates parcel of air cools as it rises

Why does water vapour cool to due point?

• Air is warmed by contact with ground/sea and rises freely through atmosphere

• As air rises pressure falls and it cools by expansion (convection)

• Air masses move horizontally across cooler surface (advection)

Lapse rates

• Vertical distribution of temp in lower atmosphere

• Temp changes that occur within an air particle as it rises

How does a cloud form?

1. Ground heated by sun and air in contact with surface heats to 18 degrees

2. Air warmer than surroundings so less dense

3. Atmospheric instability so a convection current forms

4. Temp reaches due point (8 degrees) and condensation occurs forming clouds

5. Air rises as long as internal cloud temp is higher than atmosphere

6. When equilibrium between cloud and atmosphere reached moisture evaporates or precipitates

Throughfall

Rainwater that’s intercepted

Evaporation

• Liquid water to vapour

• This is the main way water enters atmosphere

• Heat needed to break bonds of water

• Energy from heat is absorbed as latent heat and released in condensation

Interception

• Vegetation intercepts precipitations storing it on branches, leaves and stems

• Eventually moisture evaporates and falls to ground

Stemflow

Rainwater flows to the ground along branches

Infiltration

Water flows by gravity into soil and lateral movement to stream or river

Overland flow

Water flows across ground surface as a sheet or trickles to stream or river

Tree species

• Conifers have greater interception loss as they have leaves all year round

Vegetation type

• Interception is greater from grass than agricultural crops

Wind speed

• Evaporation increases with wind speed

Ablation

Loss of ice from snow, glaciers due to sublimation

sublimation

Change of ice to water vapour without becoming a liquid

Precipitation (of carbon)

• Atmospheric CO2 dissolves in rainwater to form weak carbonic acid

• Rainfall acidity increases due to anthropogenic emissions

Photosynthesis

• 6CO2 + 6H20 - C6H12O6 +6O2

• Plants and phytoplankton carry this out

• Use suns energy green plants with chlorophyll convert light energy to chemical energy

• Plants use glucose to grow and release CO2 in respiration

Weathering

• Breakdown of rocks by chemical, biological and physical processes

• Most weathering involves rainwater which has dissolved CO2

Carbonation

• calcium carbonate + carbonic acid - calcium bicarbonate

• Releases carbon from limestone, rivers, oceans

Respiration

• C6H12O6 + 6O2 - 6CO2 +6 H20 + energy

• Most organisms respire

Decomposition

• Bacteria/fungi break down dead organic matter releasing CO2

• This happens fastest in warm, humid environments

Combustion

• Organic material reacts or burns in the presence of oxygen

• Release CO2

• Natural fuel for ecosystems

• Wildfire is essential for some ecosystems

• Winter slows decomposition

• Fire then ensures carbon and nutrients are freed up

Physical Pump

• Mixing of surface and deep ocean waters by vertical currents

• CO2 enters ocean by diffusion from atmosphere

Downwelling

• Water and CO2 are transported by surface currents towards the poles and cool and sink due to density

• Carries carbon to ocean depths where it remains for centuries

Upwelling

• Deep ocean currents transport carbon to areas of upwelling

• It is then diffused back into the atmosphere

Biological pump

• Involves marine organisms transferring carbon

• Phytoplankton float near surface and photosynthesise

• Carbon in phytoplankton accumulates in sediments and is released into ocean CO2

• Marine organisms extract carbonate and calcium to manufacture skeletons and shells

• most ends up in ocean sediments and is lithified to form chalk/limestone

Vegetation

• Trees are huge stores of carbon and are essential to both water and carbon stores

• Most carbon rich material is extracted from atmosphere through photosynthesis

Dynamic equilibrium

When natural systems are unaffected by human activity and regulate their own equilibrium

Urbanisation

• Land use from rural to urban

• Soil/vegetation replaced by impermeable concrete and tarmac

• gutters, sewers and roofs remove surface water

• Causes more run off and water level rise

• Floodplains naturally store water

• Urban development reduces water store

Farming

• Forests are cleared for farms

• Reduces carbon store in vegetation, soil and biomass

• Soil carbon in pedosphere reduced by ploughing as exposure to oxidation

• Lack of biodiversity reduces carbon store

• Crop irrigation diverts water from rivers and groundwater towards land

• Interception reduced

• Surface run off increases where machinery compacts soil

How does forestry management affect water cycle?

• Higher in interception in plantations than forests

• Conifers are evergreen so high interception

• Increased evaporation as more water stored on leaves

• Reduced run off as evaporation, interception and absorption by roots is all high

• Transpiration increases

• Harvesting timber increase run off, evapotranspiration and discharge

How does forestry management affect the carbon cycle?

• Mature forests store tonnes of carbon (10x higher than grassland)

• Soil has even larger amounts carbon

• Forests have high rates photosynthesis

• Most carbon is sequestered for hundreds years

• Most carbon is in the stem

• Trees only a carbon sink for the first 100 yrs

Carbon sink

Something that absorbs more carbon than it releases

Aquifers

• Permeable rocks such as chalk and sandstone

• Groundwater is abstracted for public use from aquifers by wells and boreholes

• Upper surface of saturation is a water table

• Height fluctuates because of rainfall and drought

Artesian Basins

• They are aquifers that have been confined between two impermeable rocks

• They are under artesian pressure

• Artesian aquifer when water flows to surface under its own pressure

• London is an artesian basin

• Water is trapped in London by clay and gault clay

• Water table fell by 90cm as 19th centaury exploited water 1992 Thames water began to be abstracted

Use of fossil fuels

• Global industrialisation and urbanisation

• Dependant on fossil fuels

• 2013 87% of global energy consumption

• 10 billion tonnes year

3 stages of Carbon capture and store

• CO2 separated from emissions

• CO2 compressed and transported by pipelines

• CO2 injected into porous rocks deep underground

How can carbon capture and store help?

• Reduce greenhouse emissions by up to 90% in USA

• Undergoing a pilot program in Scotland

• High costs up to 1 billion

• Requires storage reservoirs with certain geological conditions

Positive feedback

An initial change cause further change

Negative feedback

An initial change counters a system change which restores equilibrium

What does increase temp lead to in water cycle?

• More evaporation

• Atmosphere holds more vapour

• Vapour is a greenhouse gas

• Increases long wave absorption

• High temperatures

What does lower temp lead to in water cycle?

• More vapour

• Increases long wave radiation

• Greater cloud cover

• More solar radiation reflected

• Less solar radiation absorbed

• Lower temp

What does increased atmospheric CO2 lead to?

• Photosynthesis stimulated and CO2 moves to biosphere

• Carbon moves to soil and ocean due to decomposition

• Carbon moves to sediments

• Becomes a carbon sink

What could global warming do to carbon cycle?

• Intensify carbon cycle

• Speed up decomposition

• Release more CO2 to atmosphere

Methods of monitoring water/carbon

• Satellites

• Remote sensing

• GIS means data can be mapped to show anomalies and trends

Diurnal changes

• occur within 24 hr period

• lower temp at night reduces evapotranspiration and stomata close so no CO2 taken in

• Convectional precipitation is dependant on heating of the ground by sun

Seasonal changes

• controlled by variations in solar radiation which peaks in June

• Evapotranspiration highest in summer

• Variation sin carbon are shown by NPP of vegetation

• During summer trees are in full foliage

• Phytoplankton stimulated by rise in temp in March

Glacial water cycles

• Water from ocean reservoir to ice sheets and glaciers

• sea level reduces 100m

• glaciers are 1/3 of land mass

• as ice sheets advance they destroy forest and grassland

• reduced exchange between spheres

Glacial carbon cycles

• reduction in atmospheric CO2

• changes in ocean circulation bring nutrients to the surface and stimulate phytoplankton growth

• CO2 in vegetation shrinks

• Lower ocean temp means carbon dissolves more

How has human activity affected demand for water?

• Larger demand for water

• For agriculture and human supply

• Creates water shortages

• Overuse of aquifers in Bangladesh led to incursions of saltwater making it unfit for drinking

What has urbanisation caused in the water cycle?

• Deforestation to make room for buildings

• Reduced evapotranspiration

• Lower water tables

• Decreased throughflow

What does global warming lead to in the water cycle?

• Increased evaporation

• More water vapour

• Raises global temp

• Increases evaporation

What does global warming lead to in the carbon cycle?

• Higher temperature

• Increased decomposition

• Accelerates carbon transfer from biosphere/pedosphere to atmosphere

• Permafrost carbon released

• Acidification of ocean stores

3 ways to protect carbon cycles

• Wetland restoration

• Afforestation

• Agricultural practices

Wetland restoration

• Freshwater marsh, salt marsh and peat land

• Ground is permanently saturated

• Contain 35% of carbon

• destroying wetlands releases CO2 and CH4

• Restoration raises water tables

• Removing embankments means wetlands can be reconnected to rivers

Afforestation

• Planting trees in deforested areas

• trees are carbon sinks

• reduces flood risk and soil erosion

• protection from loggers, farmers and miners

• REDD Reducing Emissions from Deforestation and Degradation

• Projects established such as Amazonia

Agricultural practices

• Overcultivation, overgrazing result in soil erosion

• Releases large carbon to atmosphere

• 100 mil tonnes CH4 from livestock

Facts about Kyoto protocol

• 1997

• Rich ACs agreed to legal binding CO2 restrictions

• some of biggest polluters(China and India) exempt

• USA and Australia refused to ratify the treaty

Facts about Paris Climate convention

• 2015

• Reduce global CO2 emissions below 60% by 2050

• Not legally binding

• Rich countries assist poor countries with funds and technology

• China/India argue Europe more responsible as past industrialisation has caused this

Cap and trade

• Polluters cut emissions and pay remissions if they don’t

• Allocated an annual quota for CO2

• They receive carbon credits if they emit less which can be traded

• Offsets are awarded to countries for afforestation

3 strategies for protecting water cycle

• Forestry

• Water allocations

• Drainage basin plans

Forestry

• Recognised by REDD, UN

• Fund programs to protect tropical forests

• 50 partner countries funded

• WWF

• 10% AMAZON BASIN covered by ARPA

Water allocations

• governments allocate water resources

• Agriculture consumers most water

• Wastage occurs through evaporation

• zero soil disturbance and drip irrigation stop the waste of water

• loss to run off stopped by contour ploughing and vegetative strips

Drainage basin plans

• Most effective water management

• Good for adapting different needs of different places

• Run off storage and groundwater is targeted

• Run off controlled by reforestation and increasing permeable surfaces

• Water storage improved by restoring wetlands