TRULY Geography carbon and water cycles

system definition and types of system

definition - a group of interacting parts connected by the flows or transfers of energy, material and matter

1. open - external inputs and outputs of enegry and matter

2. closed - systems only have energy as input / output all material is contained

3. isolated - systems not sharing energy or matter with their surroundings e.g. a coconut

   1. cascading - energy and material are transfered from one subsytem to another

Earth’s global systems

1. atmosphere - interaction of gases

2. hydrosphere - interaction of water

3. biosphere - interaction of water

4. lithosphere - interaction of the crust

components of a system - definition + examples

1. input - matter moving into a system from the outside e.g. precipitation

2. output - matter / energy moving outside the system or another system e.g. surface runoff

3. energy - power or driving force e.g. insolation

4. stores / components - parts / elements of a system e.g. puddles

5. flows / transfers - movement of parts within the system

equilibrium definition

a state of balance where inputs and outputs are equal and processes operate to maintain balance.

any disturbance will throw the system into change

feedback loops - positive, definition + example

active mechanisms in systems that maintain / restore equilibrium

positive - amplifies change, self -perpetuating

one change leads to another, change becomes bigger and throws system out of balance

e.g.

1. ice reflects radiation from the sun, reducing surface warming, as sea temperatures rise, and ice melts, the warming effect is amplified

2. there is less ice to reflect, causing higher temps and melting more ice

feedback loops - negative, definition + example

negative - ‘checks’ or dampens change - self-regulating

promotes stability and maintains equilibrium

example:

• increased photosynthesis in plants and rising global temperatures to grow in new areas e.g. melted permafrost

  • new vegetation absorbs co2 from the atmosphere, decreasing warming effect

Major stores of water

1. frozen water in the cryosphere = 68.7%

2. liquid water in the hydrosphere = 1%

3. water vapour in the atmosphere = 0.2%

4. groundwater in the lithosphere = 30.1%

the water cycle - inputs

1. precipitation - water that falls to the surface of the earth to the atmosphere including rain, snow and hail

do not confuse rainfall with precipitation as there are 3 different types of rainfall

1. convectional - heating by the sun, warm air rises, condenses at higher altitudes and falls as rain

2. relief - warm air forced upward from barriers e.g. mountains, causing it to condense at higher altitudes and fall as rain

3. frontal - warm air rises over cool air, when they meet the warm air rises and condenses at higher altitudes, causing rain

the water cycle - outputs

evapotranspiration - compromised of evaporation and transpiration (plants respiring thorugh their leaves)

streamflow - all water that enters a drainage basin will either leave through the atmosphere of throguh streams which drain the bais

the water cycle flows - infiltration and infiltration capacity

1. infiltration - water moving from above ground to soil

   1. infiltration capacity - how quickly infiltration occurs e.g. grass and trees create passages for wate rot flow through the surface of the soil

the water cycle flows - percolation and throughflow

1. percolation - water moves from soil into porous rocks, percolation rate dependant on fractures

2. throughflow - water moves through soil into streams or rivers, speed dependign on type of soil and spore spaces

water cycle flows - surface runoff and groundwater flow

1. surface runoff - water flows above the ground as sheetflow or rills

2. groundwater flow - water moves through rocks

water cycle flows - streamflow and stemflow

streamflow - water moves through established channels

stemflow - flow of water that has been intercepted by plants or trees

water cycle flows - evapotranspiration and sublimation

evapotranspiration - the combination of evaporation and plant transpiration

sublimation - when water changes from a solid into a gas without passing through a liquid stage

water cycle - stores of water

1. soil water - water in soil utilised by plants

2. groundwater - store din pore spaces of rock

3. river channel - stored in rivers

4. interception - intercepted by plants on branches and leaves before reaching the ground

5. surface storage - water stored in puddles ponds, lakes etc.

the water balace - definition and formula

water balance is used to express the process of water storage and transfer in a drainage basin system, with the formula:

precipitation = total runoff + evapotranspiration ± (change in) store

changes in the water cycle - deforestation

1. less interception by trees, increasing surface runoff

2. the soil is no longer held together by roots, so soil water storage decreases

3. there are fewer plants so transpiration decreased

changes in the water cycle - storm events

1. large amounts of water saturates the ground, increasing the surface runoff

2. storm events are therefore less effective for recharging water stores than prolonged rainfall

3. slow rainfall over a period allows water to infiltrate, storms do not allow this, leading to percolation and surface runoff

changes in the water cycle - seasonal changes

1. spring - more vegetation means more interception

2. summer - likely to be less rain, making grounds more impermeable

3. autumn - less vegetation so less interception

4. winter - frozen ground is often impermeable

changes in the water cycle - agriculture

1. pastoral farming (livestock) - trampling increases infiltration due to looser soil

2. drainage ditches increases surface runoff and streamflow

3. hillside terracing (rice fields) - increases surface water storage and therefore decreases runoff

changes in the water cycle - urbanisation

1. creating roads and buildings uses impermeable surfaces, reducing infiltration but reducing : surface runoff, reducing lag-time and increasing flood risk

2. SUDS use grass and soil to reduce impermeable surface in urban areas

soil water budget - definition and diagram

soil water budget shows the balance between inputs and outputs in the water cycle and their impact on soil storage / availability

1. the water budget is dependant on type, depth and permeability of the soil and bedrock

seasonal variation of the soil water budget

autumn - greater unput of precipitation than evapotranspiration due to cooler temp and plant photosynthesising less. soil moisture levels increase and water surplus occurs

winter - potential evapotranspiration is at a minimum due to cold temp, with precipitation continuing to refill soil water stores

spring - potential evapotranspiration increases as temperature rises

summer - hot weather leads to water utilisation of soil water as evapotranspiration peaks and rainfall is minimumm

global scale water cycle - 4 major stores

1. hydrosphere - 97% of global water and 30% is freshwater groundwater

2. lithosphere - stored in crust and lower mantle

3. cryosphere - water that is frozen

4. atmosphere - water vapour

aquifers - definition

underground water stores:

shallow groundwater aquifers - store for 200 years

deeper fossil aquifers - 10,00 years

glaciers - 20-100 years

lakes - 50-100 years

snow and rivers - 2-6 months

soil water - 1-2 months

The Inter-Tropical Convergence Zone (ITCZ

main factor in determining cloud formation and rainfall, with different zones of rising and falling air that leads to precipitation through convectional rainfall

this creates a low pressure zone on the eqautor called the ITCZ, which moves during the seasons as the suns position changes, where has Ferral and Hadley cells meet, unstable weather by the jet-stream causes changeable weather e.g. the UK

changes in the water cycle: natural processes

seasons:

1. less precipitation and increas evapotranspiration in summer

2. reduced flows in the water cycle and reduced interception in winter

storms - causes sudden increases in rainfall short-term

droughts - cause major stores to be depleted and activities of flows acting to decrease, long-term

cryospheric process - glaciers can melt and shrink casing sea levels to rise

changes in the water cycle: El Nino and El Nina

El Nino - occurs every 2-7 years and causes warm surface water to move eastward toward Sotuh America

L Nina - trade winds strengthen, causing lower temperatures and drier conditions in the US

changes in the water cycle: human impacts

farming

1. ploughing breaks up the surface

2. arable farming (crops) increases interception and evapotranspiration

3. pastoral (animals) compacts soil, reducing infiltration and increasing runoff

land use

1. deforestation reduces interception and infiltration increase

2. construction reduces infiltration and evapotranspiration

water abstraction ( removed from stores for human use)

1. increases in dry seasons and reduces store capacity

2. can reduce global long-term water stores e.g. aquifers

flood hydrographs: diagram and key components

represents rainfall in a drainage basin of a river and the discharge of the same river at the same time.

1. discharge - the volume of water passing through the cross-sectional point of the river at one point in time, measured in Cubic Metres Per Second (Cumecs)

2. rising limb - represents discharge icnrease

3. falling limb - represents discharge decrease

4. lag time - time between peak rainfall and peak discharge

5. baseflow - level of groundwater flow

flood hydrographs: flashy and subdued hydrographs

flashy:

1. short lag time

2. steep rising and falling limb

3. higher flood risk

4. higher peak discharge

subdued:

1. long lag time

2. gradually rising and falling lmb

3. lower flood risk

4. lower peak discharge

flood hydrographs: natural factors affecting surface runoff

1. high rainfall activity - higher discharge potential from rivers and soil to reach its field capacity

2. Geology - decreased percolation increases throughflow

3. high drainage density - many tributaries to main river, increasign speed of drainage, decreasing lag time

4. low temperatures - less evapotranspiration so greater peak discharge

flood hydrographs: human factors affecting surface runoff

1. urbanisation - more impermeable surfaces, so runoff increased and surface storage / infiltration reduced

2. pastoral farming - ground tramples so less interception and more surface runoff

3. deforestation - less interception by trees, increasing surface runoff

transfers in the carbon cycle - photosynthesis

Plants are sequestering carbon and reducing impacts of climate change.

the process of photosynthesis occurs when chlorophyll in the leaves of the plant react with CO2 to create carbohydrate glucose.

formula:

Carbon dioxide + water + light energy → Oxygen + Glucose

transfers in the carbon cycle - respiration

when plants and animals covert oxygen and glucose into energy, creating waste products of water and CO2:

formula

Oxygen + Glucose → CO2 + H2O

transfers in the carbon cycle - combustion and decomposition

combustion - when fossil fuels / organic matter are burnt, they emit CO2 into the atmosphere

decomposition - when living organisms, die, they are broken down by decomposers e.g. bacteria which respire, returning CO2 to the atmosphere

transfers in the carbon cycle - diffusion and weathering / erosion

diffusion - oceans can absorb CO2 from the atmosphere, increasing ocean acidity, making it the largest carbon store

weathering / erosion - rocks eroded / weathered by carbonic acid from from CO2 and rainwater, aiding erosion in rocks, e.g. limestone

transfers in the carbon cycle - burial / compaction

burial and compaction - when shelled marine organisms die, their shell fragments fall on the ocean floor, becoming compacted overtime to form limestone, and can overtime form fossil fuel deposits

transfers in the carbon cycle - carbon sequestration, adv and dis

definition - transfer of carbon from the atmosphere to other stores, being natural artificial e.g. photysnthesis and Carbon Capture and Storage (CCS)

adv:

1. fitted into existing power stations

2. caputees 90% of CO2 produced

3. potential to capture half of world CO2 emissions

dis:

1. high costs restriction

2. increased energy demand of power station

3. may not be space to fit in existing power station

flows of carbon - sere scale

a sequence of plant communities that develop overtime during ecological succession, changing the carbon stores in the area e.g.

steps towards climax:

1. Bare rock

2. lichens

3. small annual plants

4. grass, shrubs, shade intolerant trees

5. shade-tolerant trees

6. temperature deciduous forest

flows of carbon - sere scale, climatic climax

the final stage of there sere where environmental equilibrium is achieved, where the ecosystem is fully developed and stable e.g. woodland in the UK or a rainforest in Brazil

Carbon sink and Carbon store

carbon sink - any store that takes in more carbon than emits e.g. intact tropical rainforest

carbon source - emits more than it stores

Main carbon stores - marine sediments/ sedimentary rocks and oceans

marine sediments / sedimentary rocks - lithosphere, long-term

the largest store, with 66,000-100,000 million billion metric tons of carbon, recycling of this carbon can take millions of years

oceans - hydrosphere, dynamic term

2nd largest store, contains a fraction to the largest, being 38,000 billion metric tonnes, being utilised by marine organisms

Main carbon stores - fossil fuel deposits and soil organic matter

fossil fuel deposits - lithosphere - long term (but now dynamic)

largely rarely change but humans have developed technology to exploit them rapidly

soil organic matter - lithosphere - mid-term

1. store for over a hundred years, but deforestation, agriculture and land use are affecting this store

Main carbon stores - atmosphere and terrestrial plants

atmosphere - dynamic

human activity increased CO2 levels int he atmosphere by around 40% since the industrial revolution

terrestrial plants - biosphere, mid-term

1. vulnerable to climate change and deforestation as a result in climate change

information on forests and climate change:

1. non-tropical forests have seen an increase in carbon sequestration due to conversation of agricultural land and plantations to new forests

2. forests in industrialised regions are expected to increase by 2050

3. rate of forest loss has declined, from 9.5 million in 1990 to 5.5 million in 2015

carbon cycle changes over time - natural processes

wildfires - transfer from biosphere to atmosphere as CO2 is released through burning. can have short-term changes but the long term benefit of encouraging plant growth

volcanic acitvity - change from lithosphere to atmosphere, contribute relatively low proportion of CO2, often short-term imapcts

carbon cycle changes over time - human activity

fossil fuel use - combustion changes a long-term carbon sink into a carbon source, increasing the global and personal carbon footprint

deforestation

famring practices - Pastoral farming releases Co2 as animals respire, ploughing can also release Co2

changes in carbon stores - using tech to access fossil fuels

carbon budget definition

the balance between carbon inputs and outputs to a store at any scale, or the balance of exchanges

the enhanced greenhouse effect - definition

the process that is currently causing abnormally high greenhouse gases being produced by humans

important in deciphering between this and the normal greenhouse effect, as that is a natural process

radiating forcing - the difference between incoming solar radiation absorbed by the Earth and the energy radiated back into space

the enhanced greenhouse effect - causes

1. land use change - 1/10th of carbon release annually e.g. Farming Practices, with 70% being cattle, which produces methane

2. fertilisers - e.g. rice padi fields, from which methan emissions have increased as a result of increased productivity

3. deforestration - 20% of all global greehouse emissions, making the land a carbon source rather than a carbon sink

4. urbanisation - 2% of world’s land mass but accounts for 97% of all human caused co2 emissions

Milankovitch Cycles

1. Ice core data presents the variations in Earth’s orbit cause periods where we gain greater heating from the sun, increasing global temps rather than greenhouse

2. this creates a psoitive feedback as heating melts flaciers and increases flows in carbon cycle

3. the study is not widely agreed on, with only 3% of scientists using this for the main reason for climate change

impact of the carbon cycle on regional climates - tropical rainforests and oceans

tropical rainforests

1. high rates of photsynethis and transporaiton icnreases humidity, cloud cover and precpitation

2. deforestation reduces this effect

oceans

1. warm oceans cause plankton growth, and through plankton chemical prodction, cause clouds to form

2. warm oceans store less CO2 as carbon sinks

Land drainage in moorland (peatland) areas

an areas of waterlogged, acidic soil and peat which stops oxygen from permeating, making them major stores of CO2

1. many have been drained by large channels, making them no longer submerging

2. often turned into farms or plantations, which can increase flood risk

3. the dry peat degrades easily

4. as water table lowers, air is able to aid decomposition releasing the stored co2

interrelationships between water and carbon cycle - natural rainforest water and carbon cycle

water cycle:

1. 75% intercepted by trees through stem flow

2. 35% reaches the fround

3. another 85% used by plants through transpiration

4. 25% evaporates almost immediatly

carbon cycle:

1. trees suited to warm conditions, promoting photosynthesis

2. absorb large amounts of oxygen from the atmosphere acting as a carbon sink

interrelationships between water and carbon cycle - deforested rainforest water and carbon cycle

water cycle

q. most reaches the ground immediately due to little runoff

less evapotranspiration so atmosphere is less humid and rain decreases

carbon cycle:

1. lack of trees so photsynthesis reduced

2. fires to clear land leads to co2 rleased, making forests a carbon source

relationships between the two cycles

1. rain over deforested land can cause soil erosion, with it collecting ash into rivers, increasing carbon content in rivers

2. there is reduced rainfall in the intact forest due to less evapotranspiration in the deforested area, causing drought periods

3. deforestation in peatland and digging drainage channels reduces water storage, meaning peat matter underwater decomposes quicker, releasing CO2 into the atmosphere

mitigating climate change - mitigation and global intervention

mtigation techniques:

1. setting targets to reduce emissions of greenhouse gases

2. using renewable energy

3. ‘capturing’ carbon emissions

global scale

1. Paris Agreement - aim to limit global temp to 2 degrees above pre-industrial levels

2. public interacitona nd awareness schemes

mitigating climate change - regional, national, and local

regional

1. 20% reduction in greenhouse gas emissions and 20% renewable energy by 2020

national

1. legally binding target to reduce GHG emissions by 80% by 2050 with a target of 26% in 2020

local

1. recycling

2. being energy wise e.g. smart meter

3. improving home insulation

Amazon Rainforest - carbon cycle

• Emits 1.9 billion tonnes of carbon in a year through decomposition and organic respiration  

• Holds 17% of global terrestrial vegetation carbon stock  

• Account for 30-50% of global photosynthesis  

• Overtime have become less efficient 

• Stopped being a carbon sink around mid 2010’s,  

Amazon Rainforest - water cycle

• Annual rainfall of 2300 mm  

• Produces 1/3^rd of its own precipitation in recycling of evapotranspiration -> this is reducing as cleared land means air is less moist = less cloud  

• Up to half the rainfall may never reach the ground due to interception and re-evaporation, river surfaces, by transpiration on plant leaves 

human factors on Amazon rainforest - Mcdonald’s shift to pastoral agriculture

• McDonald’s farms on ex-rainforest land contributing to excess methane 

• Estimated to  be 100,000 cattle ranches in the Amazon, contributing to decrease in water retention and lack of supply to indigenous tribes 

• Pastoral farming soil can only hold 1kg of co2/m2 compared to 4-9kg m2 in natural rainforest soil  

human factors on Amazon rainforest - Urbanisation in Manaus

1. Between 1970 and 2003, the population in Manaus grew by 300k  

2. More population leads to more deforestation, with it being the fastest growing of Brazil’s 10 cities in 200-2010 by far  

3. Rapid urbanisation said to have increased precipitation by 0.8mm per hectare 

human factors on Amazon rainforest - water abstraction from Brazil

• Pressure on water resources in the Amazon is very low due to low population density and availability of water  

• For the rest of Brazil, water is needed, so in 2006 2108 million m3 / 3.6% of Brazil's national water was withdrawn from the Amazon  

• Over ½ used by agriculture and livestock  

• Domestic and urban used 1/3^rd  

Physical factors on the amazon rainforest- Rio Negro floods

1. For over 1 month, Carreiro da Várzea was underwater, effecting 40 areas and 300,000 people 

2. Since the end of 2013, heavy rains pushed Rio Negro to emergency levels 

3. Explained due ot the unexpected change in weather systems meaning more water vapour, consequently, more rain 

4. If they don’t have a record flood, they have a record drought 

physical factors affecting the Amazon- Drought increase from 2005 to 2010

• Feedback loop: droughts -> fewer trees -> reduced rainfall -> more droughts

• Scientists found changes between 2005 and 2010 in the rainforest:  

• The forest has become more carbon natural  

• Precipitation anomalies reduced tree growth  

• Tree mortality was higher  

Carbon budget definition

comparing how much carbon is being emitted to what is absorbed or captured

1. includes carbon emissions from human and natural sources

2. as well as human and natural sequestration

Carbon sequestration

• Natural – carbon removed from the atmosphere, stored in liquid or solid form e.g. rocks in lithosphere, plants in biotsphere and formation of hydrocarbons  

• Carbon capture and storage (CSS) - technological process of capturing CO2 from industrial sources, being seperated, treated and transported to a long-term

carbon cycle at plant / tree scale

• A tree’s wood acts as a carbon store, as wood is about 50% carbon  

The transfer of carbon to atmosphere, biosphere and pedosphere takes place through:  

1. Photosynthesis – tree removes CO2 from the atmosphere  

2. Respiration – tree and microbes in the soil, return carbon to the atmosphere as CO2 

3. Decomposition – leaf litter and death of tree also returns carbon to atmosphere and soil 

4. Combustion – wildfires release large quantities of stored carbon  

carbon cycle and a sere scale

Sere – a stage in the succession of vegetation in an ecosystem: 

1. Each step of vegetation is a sere  

2. Pioneer species – the start of the sere 

3. Climax communities – the end of growth fo nature and vegetation, in the UK this is normally a deciduous woodland  

4. Sere scale involves various factors which vary over space and time  

3 types of carbon cycles in the oceans:

physical pump

biological pump

carbonate pump

sere carbon cycles in oceans - Physical pump

• Most important  

• CO2 absorbed by the ocean surface through diffusion 

• Taken from surface to deep ocean stores through downwelling  

• Cold water absorbs more CO2 so more co2 is absorbed at the poles  

• Makes the water denser, making it sink, allowing for more diffusion

sere carbon cycles in oceans - biological cycle

• Sequesters carbon through photosynthesis by phytoplankton / marine animals, converting CO2 into organic matter 

• Acts a biologica pump transporting carbon from ocean’s surface to intermediate and deep ocean stores  

• As they die, the parts of them sink to the bottom, decayign and releasing carbon into deep water stores 

sere carbon cycles in oceans - solubility cycle

1. CO2 absorbed by oceans forms carbonic caid, reacting with hydrogen ions to form bicarbonates and further reactions with carbonates stored in upper oceans 

2. Used for shells / skeletons, with them dying sinking carbon sequested material to the sea bed, overtime becoming rocks like limestone