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WATER & CARBON, Processes of change... Precipitation = transfer of…

- - - - rock is vulnerable to weathering processes
        when exposed
        
        carbon may be released when it breaks down
        
        gradually vegetation grows on the bare rocks and
        carbon exchange starts to take place
      - soil = important component
        
        absorbs and stores carbon over moderate time periods
        
        tree species become more diverse benefiting the supply
        of carbon in the soil
        
        vegetation succession = sequence of changes
        
        sere = succession that relates to a specific environment (each stage = seral stage)
      - climatic climax = final stage of sere where environmental equilibrium is achieved
        
        usually in response to the climate
        
        in the UK this would be a woodland
    - - Photosynthesis = plants use light energy from
        the sun to produce carbohydrates in the form of glucose
        
        CO2 + Water ---(light energy)---> Glucose + oxygen
        
        by removing CO2 from the atmosphere, plants are sequestering carbon / reducing impacts of climate change
        
        process occurs when chlorophyll in the leaves of the plants react with CO2 creating carbohydrate glucose
        
        some glucose is used in respiration but the rest is converted to starch
      - Respiration = chemical process that occurs when plants and animals convert oxygen and glucose into energy
        
        Oxygen + glucose ---> CO2 + Water
        
        energy can be used for growth, repair, movement ect
      - Decomposition = when organisms die they are consumed by decomposers which respire, returning CO2 back to the atmosphere
        
        some organic matter is returned to the soil where it is stored
      - Combustion = when fossil fuels and organic matter are burned, they emit CO2 into the atmosphere
        
        CO2 is released into the atmosphere returning the carbon
      - Burial & Compaction = organic mater is buried by sediments and becomes compacted
        
        shelled organisms die, their shells accumulate on the seafloor and some carbonates dissolve releasing CO2 / some compact to form limestone
      - Carbon sequestration = transfer of carbon from atmosphere to other stores (artificial and natural)
        
        plants sequester carbon when it photosynthesises and stores carbon in its mass
        
        carbon capture and storage (CSS) = technological capturing of up to 90% of emissions produced from fossil fuels
        
        CO2 is captured and transported via pipeline to depleted gas fields and saline aquifers
      - Weathering = decay of rocks in their original place by carbonation weathering
        
        CO2 mixes with rain water to create carbonic acid which aids erosion
        
        transported via water cycle to oceans = used to build shells of marine life
  - - - Marine sediments & sedimentary rocks
        
        lithosphere - long-term (largest store)
        
        100000 billion metric tonnes
        
        rock cycle / continental drift recycle rocks over time
      - Ocean
        
        hydrosphere - dynamic
        
        38000 billion metric tonnes
        
        CO2 directly absorbed from air / river water discharges carbon in solution
        
        carbon utilised by marine organisms
      - Fossil fuel deposits
        
        lithosphere - long-term (currently dynamic)
        
        4000 billion metric tonnes
        
        hydrocarbons have been exploited for heat and power since the industrial revolution
        
        humans have developed technology to exploit them
      - Soil organic matter
        
        lithosphere - mid-term
        
        1500 billion metric tonnes
        
        soil can store carbon for hundreds of years but deforestation, agriculture and land use change affect this
      - Atmosphere
        
        dynamic
        
        750 billion metric tonnes
        
        human activity has caused CO2 levels in the atmosphere to increase by around 40% since industrial revolution
        
        led to enhanced greenhouse effect
      - Terrestrial plants
        
        biosphere - mis-term
        
        560 billion metric tonnes
        
        plants convert energy from the sun into carbs
        
        vulnerable to climate change and deforestation
    - - scientists have identified that carbon uptake is increasing in middle and high latitudes of the northern hemisphere, but less carbon is being absorbed in the tropics and southern hemisphere
      - major cause of decrease is through to be drought = impacts crop yields, timber production and expanses of natural vegetation
      - non-tropical forests have seen an increase in carbon sequestration in recent years = due to conversion of agricultural land and plantations to new forests
      - forests in industrialised regions are expected to increase by 2050
      - 7 countries with the largest forest areas = Russia, Brazil, China, Canada, USA, Australia, Indonesia
      - Brazil has the most carbon stored on land and the most extensive deforested area
        
        China has the largest amount of afforested area
    - - Climate change
        
        during the Quaternary geological period global climates fluctuated between warm (interglacial) and cold periods (glacial)
        
        increase in CO2 leads to enhanced global warming / lower levels leads to global cooling
        
        impacts of cold conditions
        
        chemical weathering processes more active
        
        decomposers would have been less effective (carbon transfer to soils = reduced)
        
        less water flowing into oceans / less sediment transfer
        
        soil frozen over vast areas of land
        
        impacts of warm conditions
        
        global temps have risen
        
        melting of permeafrost in tundra regions
        
        carbon released inot atmosphere enhancing greenhouse effect
        
        positive feedback
      - Wildfires
        
        transfer carbon from biosphere to atmosphere as CO2 is
        released through burning
        
        can turn forests from being a carbon sink to a carbon source (combustion returns huge quantities of carbon back to the atmosphere)
        
        can encourage growth of plants in long term
      - Volcanic activity
        
        carbon is released during eruptions (as CO2)
        
        Palaeozoic era = volcanoes more active than today
        
        contribute low level of CO2 to the carbon cycle
        
        eruptions produce sulphur dioxide gas which enters the
        atmosphere blocking radiation from the sun = lowering temps - reduce photosynthesis rates (affects water cycle)
    - - Fossil fuel combustion
        
        natural sources of energy formed from the remains of living organisms
        
        transfers CO2 to the atmosphere from a long-term carbon sink
        
        mainly composed of carbon and hydrogen ('hydrocarbons')
        
        global warming increased since industrial revolution
        
        Hawaiian Volcanic Observatory = since 1950s have measured CO2 showing a huge increase
      - Intergovernmental panel on climate change (IPCC) -
        90% of anthropogenic carbon release comes from the
        combustion of fossil fuels / 10% comes from land-use
        change
      - Farming practices - land use change
        
        ploughing, artificial fertilisers etc release carbon
        
        methane is a potent greenhouse gas (raised issues worldwide about the desirability of moving away from a high dependence on meat and dairy products)
        
        methane produced from cultivation of rice (up to 20% global methane production)
      - Deforestation
        
        carbon neutral = tree dies and decomposes over a long period of time / new vegetation starts to grow
        
        deforestation by 'slash and burn' = interrupt carbon cycle by rapidly releasing carbon
      - Urbanisation
        
        stores are either replaced or covered by impermeable surfaces
        
        cement production contributes about 2.4% og global carbon emissions
  - - - Land
        
        carbon cycle responsible for development of soil
        
        carbon in form of organic matter introduces nutrients
        
        organic matter = essential for plant growth / food
        
        carbon provides source of energy in form of wood /
        fossil fuels
      - Ocean
        
        carbon converted into calcium carbonate = used by
        marine organisms to build shells
        
        impact on phytoplankton - consumes CO2 which is then
        passed through the marine food chain
      - Atmosphere
        
        CO2 helps warm the earth through the greenhouse effect
        
        increases in CO2 as a result of human activities - threatens
        world climate
        
        carbon stored by atmosphere has effect on atmosphere
  - - - Land-use change
        
        farming practices
        
        cattle produce methane
        
        10th of carbon release annually / impacts short-term stores
      - Fertilisers
        
        methane emissions have increased as a result of
        increased productivity due to higher CO2 levels
        
        more sustainable grains / seeds are being considered
        substitutes = require less water to grow
      - Deforestation
        
        accounts for 20% of all global greenhouse emissions
        
        impact when the land is used for other purposes = reduces
        carbon sequestration and land becomes a cerbo source not sink
      - Urbanisation
        
        urban areas occupy 2% of worlds land mass
    - - Modifying industrial combustion
        
        Carbon capture and storage (CCS)
        
        uses technology to capture CO2 from coal-fired power stations
        
        once captured the carbon is compressed / transported by pipeline to an injection well
        
        then injected as a liquid into suitable geological reservouirs
      - Modifying photosynthesis
        
        plantation forests (7% global forest area) are effective
        in absorbing CO2
        
        IPCC = legitimate option for reducing climate change
      - Modifying deforestation
        
        consumers encouraged to buy wood only certified by the Forestry Stewardship Council (FSC)
      - Paris Agreement - 2015 (COP21)
        
        195 countries adopted a climate deal
        
        aims to limit average global temp increase to 1.5 degree
        
        meet every 5 years to set more ambitious targets
        
        provide adaptation support for developing countries
        
        developed nations will continue to support initiatives in developing countries aimed at reducing emissions
      - Local scale
        
        improving home insulation
        
        recycling
        
        using energy more wisely (smart metres) / public transport etc
  - - - wildfires more likely in hotter / drier climates caused
        by global warming which release CO2 increasing the
        warming effect
        
        ice reflects radiation from the sun reducing surface
        warming. As sea temps rise, the earmgin effect is
        amplified and there is less ice to reflect radiation and
        further melting occurs
    - - global warming enhanced by CO2 emissions
        
        higher temps and higher levels of CO2 increase
        photosynthesis rate and create new areas of vegetation
        
        CO2 taken in by plants through photosynthesis
        
        less CO2 in the atmosphere reduces warming effect
        
        photosynthesis returns to post-warming levels
  - - - impact of human activity...
        
        photosynthesis ceases until new plants colonise
        
        plant / animal respiration drops to zero
        
        rain washes ash into the ground increasing carbon content of the soil
        
        decomposers largely absent from environment
        
        carbonised wood = black burned stumps
- - - - Hydrosphere = liquid water
      - Lithosphere = water in crust and
        upper mantle (land)
      - Cryosphere = frozen water
      - Atmosphere = water vapour / air
    - - crucial for sustaining civilisation
        across the world
      - most commonly form in rocks such as chalk
        and sandstone (porous and permeable)
      - soil water budget = water enters rocks
        either directly or slowly and vary in their capacity
        to store and transfer water
      - water table = upper level of saturated rock
        
        rises and falls in response to groundwater flow
        and water abstraction
        
        needs to be at equilibrium - through management
      - fossil aquifers = formed during wetter climatic
        periods (deserts of Africa and the Middle East)
    - - global atmospheric circulation model = main
        factor that determines cloud formation and rainfall
      - ITCZ = different zones of rising and falling
        air that leads to precipitation through convectional
        rainfall creating a low pressure zone on the equator
        
        has heavy rainfall / monsoons
      - moves during seasons:
        
        north and south as the sun changes positions
        
        sun illustrates spatial and temporal changes in
        transfers and store magnitudes
      - where Ferrel and Hadley cells meet unstable
        weather occurs and is moved by the jet stream
        (upper-level winds)
        = changeable weather
      - mid latitudes = cloud formation is driven by convergence
        of warm air from Tropics and cold from the Arctic
    - - Cryospheric processes
        
        glaciers and ice caps stored significant
        proportions of freshwater through accumulation
        (addition of mass to a glacier - precipitation / snow)
        
        95% ice is in ice sheets - Antarctica and Greenland
        
        long-timescale - snow falling on glacials and ice
        sheets becomes compressed foring glacial ice layers
        
        Short-time scale = snow accumulates during winter to add to the mass of the ice sheet / glacier
        
        summer =melting / carving
        
        most are now shrinking and retreating = sea level rise
        
        total melt of ice sheets = 60m rise in sea level
        
        positive feedback loop - rising sea levels destabilize ice
        sheets, triggering carving and further melting
      - Seasonal changes
        
        summer = less precipitation, more evapotranspiration
        due to higher temps
        
        increased evapotranspiration - deciduous trees have their
        leaves / higher temps
        
        winter = reduced water flows as water is
        stored as ice
        
        reduced interception as deciduous trees loose
        their leaves
      - El Nino & La Nina
        (occurs every 2-7 years)
        
        El Nino effect = causes warm temps in
        a predictable way
        (climate change increases probability)
        
        La Nina = causes cooler temps in
        a predictable way
      - Climate change
        
        1/3 of earths land area was
        covered by glaciers/ ice sheets at
        the peak of the last ice age
        
        magnitude of ice store increased
        significantly with water 'locked up'
        
        sea level fell by over 100m (less
        water reached the oceans)
        
        warmer periods - ocean levels were 50m
        higher than they are today
      - Soil water budget
        (shows annual balance between inputs
        and outputs and their impacts on storage)
        
        budget is NEVER the same due to
        varying conditions throughout the year
        and is affected by previous rainfall
        
        depends on type / depth of soil, texture
        and permeability of soil and bedrock
        
        Field capacity = max possible storage level of water
        
        once reached any rainfall after will not infiltrate =
        flooding
        
        Wet seasons
        
        precipitation exceeds evapotranspiration
        = water surplus
        
        ground water stores fill with water
        
        more surface run off
        
        higher discharge = river levels rise
        
        Drier seasons
        
        evaporanspiration exeeds precipitation = ground
        store depleted
        
        some flows into river channel but not replaced by precipitation
    - - natural
        
        Droughts
        
        causes reduction in water stores in river / lakes
        
        vegetation dies (affects transportation, interception,
        infiltration)
        
        ground dries up and trees transpire less
        
        soils dry out (soil water store is reduced and
        throughflow ceases)
        
        Storms
        
        rainfall saturates ground to its field capacity
        
        increases surface runoff
      - human
        
        Land-use change
        
        urbanisation = makes flooding more likely
        as overland flow increases
        
        deforestation = reduces interception, evapotranspiration
        and infiltration increases
        
        Farming practices
        
        ploughing breaks up surface = increased infiltration
        
        arable (crops) = increase interception / evapotranspiration
        
        pastoral (animals) = compacts soil, reducing infiltration and
        increases runoff
        
        irrigation = removes water from rivers decreasing their flow
        
        Water abstraction
        
        removed from aquifers
        
        reduces volume in surface stores
        
        water abstraction increases in dry seasons = depletion
        
        human abstraction is often greater than inputs =
        decline in global water stores
        
        aquifers can become contaminated by inflowing saltwater
  - - - characteristics...
        
        small basin = rapid water transfer
        
        high density speeds
        
        impermeable rock = overland flow
        
        urbanisation = rapid water transfer
        
        steep slopes = rapid water transfer
        
        saturated soil = overland flow
        
        heavy rainfall = exceeds infiltration capacity
      - natural...
        
        high rainfall intensity
        
        impermeable underlying geology
        
        high drainage density
        
        small basin
        
        circular basin
        
        vegetation cover
      - human...
        
        urbanisation
        
        pastoral farming
        
        deforestation
    - - characteristics...
        
        large basins = slow water transfer
        
        low density = slow transfer
        
        permeable rocks = slow transfer by groundwater flow
        
        forest = interception slows flow
        
        gentle slopes = slow water transfer
        
        dry soil = absorbs water and slows transfer
        
        light rain