Water and Carbon Cycles and Global Governance Flashcards

The Concepts of System and Mass Balance in the Water Cycle

The Water Cycle as a System: The water cycle (or hydrological cycle) is classified as a system because it is a complex, interconnected set of processes that continuously moves, stores, and transforms water across the Earth's surface, atmosphere, and underground. It involves specific components (stores), mechanisms for movement (flows/transfers), and energy inputs.
System Components: * Inputs: Water entering stores, primarily through precipitation. * Outputs: Water leaving stores, such as evaporation. * Stores: The main locations where water is held, including the oceans, glaciers and ice caps, groundwater, surface freshwater, the atmosphere, and organisms. * Flows (Transfers): The movements of water between stores. These include transpiration, sublimation, evaporation, condensation, advection, precipitation, melting, freezing, surface runoff, infiltration, percolation, stem flow, and groundwater flow.
Mass Balance (Water Budget): This is the application of the conservation of mass principle to hydrological systems. It states that the total water entering a system (inputs) minus the water leaving (outputs) equals the change in storage over time ( $\Delta S = \text{Inputs} - \text{Outputs}$ ). The cycle is driven by the sun and gravity, ensuring that globally, water volume remains constant across the atmosphere, land, and oceans.
Storage Across Spheres: * Hydrosphere: All water on Earth in solid, liquid, or gas form. * Cryosphere: Areas where water is present as snow or ice, including ice sheets, ice caps, alpine glaciers, sea ice, and permafrost. * Biosphere: All living organisms, such as plants, animals, birds, fungi, insects, and bacteria. * Atmosphere: The gas layer between Earth's surface and space, held by gravity. * Lithosphere: The Earth's outermost part, comprising the crust and upper mantle.

Sea Level Change and Changing Water Stores

Groundwater Salinization (Aquifers): Rising sea levels cause saltwater to infiltrate freshwater aquifers in low-lying coastal areas. By $2100$ , under high-emissions scenarios, approximately $60$ million people may lose $5\%$ or more of their fresh groundwater. Regions like the Mekong Delta and the eastern USA are projected to see significant declines.
Rising Water Tables (Groundwater Shoaling): Sea level rise forces the groundwater table upward. This can lead to "groundwater flooding," impacting subterranean infrastructure like basements, sewers, and roadbeds even before surface coastal flooding occurs.
Coastal Wetland Loss: Mangroves and tidal marshes are being submerged or "squeezed" against human developments. Studies suggest up to $78\%$ of global coastal wetlands could be lost by $2100$ if they cannot migrate inland.
Reduced Freshwater Storage: As saltwater replaces freshwater in aquifers and wetlands are lost, total available freshwater storage in coastal regions decreases.
Compounding Factors: Human activities like groundwater pumping cause land subsidence, making relative sea level rise faster, while draining wetlands for development further accelerates storage loss.

Cryospheric Processes and Water Transfers

Accumulation (Input): Snowfall, condensation, and avalanche deposits add mass to glaciers and ice sheets. During glacial periods, increased accumulation lowers global sea levels by locking away water.
Ablation (Output): Melting, sublimation (solid to gas), and calving (icebergs breaking off) release water. High global temperatures currently increase ablation, leading to negative mass balance and decreased storage.
Seasonal Fluctuations: Snow and sea ice grow in winter and shrink in summer, creating annual variations.
Long-Term Impact: Sustained ablation leads to a "peak water" scenario; glaciers shrink until they can no longer provide significant runoff, threatening downstream water supplies for agriculture and communities.
Permafrost Change: Melting permafrost alters landscape storage and subsurface flows, creating either wetter or drier conditions depending on soil type.
Key Transfers Explained: * Precipitation: Water falls as rain, snow, sleet, or hail, replenishing surface and groundwater. * Evaporation: Liquid water changes to gas via solar heat, primarily from oceans and lakes, replenishing atmospheric moisture. * Transpiration: Plants release water vapor through leaf pores (stomata), contributing to cloud formation and atmospheric moisture.

Catchment Hydrology and the Drainage Basin System

The Drainage Basin: An area of land where all flowing surface water converges to a single point (river mouth, lake, or ocean). It is separated from adjacent basins by a drainage divide (ridges or hills). Basins are hierarchical, consisting of smaller basins merging at confluences.
Types of Precipitation as Inputs: * Convective: Sun heats the ground, warm air rises rapidly, cools, and condenses, causing heavy showers or thunderstorms. * Orographic (Relief): Air masses are forced upward by mountains, cooling and causing rain on the windward side. * Cyclonic (Frontal): Warm air meets cold air at a front; the denser cold air forces warm air to rise, leading to prolonged rain.
Flows in the System: * Throughfall: Rain dripping from leaves/branches. * Stemflow: Water flowing to the ground via stems and trunks. * Infiltration: Water moving from the surface into the soil. * Overland Flow: Sheet of water moving across the ground surface. * Throughflow: Lateral movement through soil via pores and fissures. * Percolation: Water transfer from soil into underlying bedrock. * Groundwater Flow: Vertical and lateral movement through rock due to gravity/pressure. * Channel Flow: Movement within streams and rivers.
Stores in the System: * Interception Store: Leaf and plant surfaces. * Vegetation Store: Water held within biomass. * Surface Store: Water in depressions, hollows, or snow cover. * Soil Moisture Store: Water in soil pore spaces. * Channel Store: Water held in the river channel. * Groundwater Store: Water in solid rock or superficial deposits (gravels).
Outputs: * Evaporation: Liquid to gas state change. * Transpiration: Diffusion from vegetation via stomata. * Channel Discharge: Volume of water leaving the basin via the main river per unit of time.

Temporal Variations in River Discharge

River Regime: Annual discharge pattern at a specific point. * Simple Regime: One peak per year. * Complex Regime: Multiple tributaries flowing through varied climates/environments.
Factors Influencing Regimes: * Climate: High rainfall intensity leads to consistent discharge; cold climates store water as snow, causing spring melt peaks; high temperatures increase evapotranspiration. * Season: Winter sees lower evapotranspiration in temperate zones (higher baseflow); Spring brings snow-melt peaks; Summer sees high evaporation and lower discharge; Monsoons cause massive rapid spikes. * Geology: Impermeable rock (clay/granite) causes "flashy" regimes (rapid surface runoff); permeable rock (chalk/limestone) allows infiltration and stable baseflow. * Vegetation: Interception slows arrival at the ground; transpiration reduces available runoff; deciduous trees allow more winter throughfall. * Land Use: Urbanization (tarmac/concrete) speeds runoff; deforestation increases peak discharge; agriculture (ploughing) can increase infiltration but drainage ditches speed transport; dams allow discharge regulation.
Climatic Factors Affecting Storm Hydrographs: * Precipitation Type: Snow delays peak discharge; rain produces a faster response. * Precipitation Amount: High amounts lead to higher peaks and faster rising limbs. * Precipitation Duration: Prolonged rain saturates soil, increasing runoff and sustaining peaks. * Precipitation Intensity: High intensity (thunderstorms) exceeds infiltration capacity, causing immediate overland flow and a "flashy" hydrograph. * Temperature: High heat increases evaporation; freezing temperatures act as storage. * Antecedent Conditions: Saturated ground leads to immediate high runoff (flashy hydrograph); dry soil can absorb more water, increasing lag time.

River Catchment Characteristics and Hydrographs

Size: Large basins have longer lag times but higher total peaks. Small basins have shorter lag times.
Shape: Circular basins have short lag times (simultaneous arrival of water); narrow basins have flatter hydrographs.
Drainage Density: High-density networks transport water efficiently, leading to higher peak flows.
Porosity/Permeability: Permeable rocks increase baseflow; impermeable rocks lead to steep rising limbs.
Slopes: Steep slopes result in faster gravity-driven runoff and shorter lag times.
Vegetation: Increases interception and roots enhance infiltration, lowering the peak.
Land Use: Urbanization and deforestation create rapid water transfer and high peaks.

Precipitation Excess and Runoff

Air Uplift and Cloud Formation: Air is forced upward (convection, fronts, topography, convergence), causing expansion and cooling. At the dew point, water vapor condenses on nuclei to form clouds.
Theories of Precipitation Formation: * Bergeron-Findeisen: High-altitude clouds contain water droplets and ice crystals; crystals grow by attracting vapor, fall, and melt into rain. * Collision Coalescence: "Supersized" sea salt nuclei act as seeds for large droplets that fall and absorb smaller droplets.
Causes of Excess Runoff: * Prolonged Precipitation: Saturates soil to "field capacity," resulting in wide-scale, slow-building floods. * Intense Storms: Rainfall exceeds infiltration rate (Hortonian overland flow), causing flash floods in urban or dry areas. * Monsoon Rainfall: In regions like Southeast Asia, $70\%$ of annual rain falls in $100$ days, overwhelming drainage. * Snowmelt: Rapid temperature rises melt snow over frozen/saturated ground, causing "freshet" flooding.
Human Causes of Excess Runoff: * Urbanization: Impermeable surfaces and artificial drainage (culverts/gutters) rush water into rivers, reducing interception and storage. * River Mismanagement: * Channelisation: Straightening rivers causes a "downstream rush." * Culverting: Narrow pipes can block and cause severe local flooding. * Dredging: Speeds water but removes features that slow flow. * Deforestation: Reduces riparian bank stability and interception. * Artificial Levees: Trap water but can cause destructive floods if overtopped.

Water Cycle Deficit and Aquifers

Deficit Definition: A condition where water demand/outflow exceeds input/supply, resulting in a negative balance.
Causes of Deficit: * Seasonal Variations: Monsoonal cycles, high summer temperatures (evapotranspiration), dry winters. * Climate Change: shifts rain belts, reduces snowpack, increases "flash" droughts, and creates positive feedback loops where dry soil heats up and further inhibits clouds. * Human Use of Aquifers: Extraction for agriculture ( $70\%$ of global use), industry, and municipal needs often exceeds natural recharge. This leads to ground subsidence, saltwater intrusion, and reduced surface water baseflow.
Aquifer Features: Water-bearing rock that transmits water to wells. "Fossil" water is nonrenewable deep water; using it contributes to sea level rise as it leaves the terrestrial cycle for the marine cycle.
Recharge Methods: * Natural: Precipitation infiltration and surface water leakage from rivers/lakes. * Artificial (Managed Aquifer Recharge - MAR): Infiltration basins, injection wells, check dams, and rooftop rainwater harvesting.
Case Study: Central London Aquifer: * The Chalk and Thanet Sands aquifer is confined by Lambeth Group clay. * Industrial decline since $1960$ led to rising groundwater levels, threatening subterranean infrastructure. * GARDIT (General Aquifer Research, Development and Investigation Team): An EA management strategy to control levels via artificial recharge schemes like NLARS (North London) and WARS (Wandle). * Success of Recharge: Global MAR contributes $\approx 10\,km^3/\text{year}$. The North China Plain has seen levels rise $0.7\,m/\text{year}$ since $2020$ due to active management.

The Global Carbon Cycle

The Carbon Cycle as a System: Consists of reservoirs (atmosphere, oceans, soil, rocks, biosphere) exchanging carbon through fluxes like photosynthesis and respiration.
Main Stores (Sinks): * Lithosphere: The largest store (sedimentary rocks like limestone and fossil fuels). * Hydrosphere: Deep ocean water holds the majority of marine carbon. * Biosphere: Terrestrial ecosystems. * Atmosphere: Mostly $CO_2$ and methane ( $CH_4$ ).
Key Processes (Fluxes): * Photosynthesis: $CO_2 + \text{sunlight} \rightarrow \text{glucose } (C_6H_{12}O_6) + O_2$ . * Respiration: Organisms break down glucose, releasing $CO_2$ . * Decomposition: Microbes break down organic matter into $CO_2$ or $CH_4$ (anaerobic). * Combustion: Wildfires and fossil fuel burning release stored carbon. * Diffusion (Physical Pump): $CO_2$ dissolves in cold polar waters (sinking) and is released in warm equatorial waters. * Biological Pump: Phytoplankton convert inorganic carbon to organic matter; upon death, this "marine snow" sinks to the deep ocean/seafloor to form limestone over millions of years. * Weathering: Carbonic acid ( $H_2CO_3$ ) in rain reacts with rock minerals, releasing ions transported by rivers to the ocean.

Carbon Stores in Biomes and Human Impact

Tropical Rainforests: Stores $550\,GtC$ ; high biomass focus ( $180$ tonnes/ha above ground); rapid decomposition due to heat/moisture; heavy rain causes soil leaching.
Temperate Grasslands: Stores $185\,GtC$ ; focus is $90\%$ belowground in roots and soil humus ( $100\text{--}200$ tonnes/ha); resilient to fire; slower decomposition in cooler climates.
Human Activity: * Deforestation: Soya crop cover ( $2.7$ tonnes/ha) replaces rainforest ( $180$ tonnes/ha), reducing storage. * Afforestation: REDD scheme provides financial incentives for conservation. Monoculture can increase storage if replacing smaller biomes. * Agriculture: Soil erosion reduces storage; crop rotation and manure can increase it.

Peatland Dynamics and Restoration

Peat Definition: Sticky, wet, carbon-rich soil consisting of partially decomposed vegetation (mosses, rushes).
Formation: Occurs in waterlogged, anaerobic upland areas (e.g., Northern Scotland). High precipitation and cold temperatures keep decomposition rates lower than photosynthesis fixation rates.
Reduction Causes: Extraction for fuel/horticulture, drainage for agriculture (allows oxygen penetration and aerobic decomposition), and fire risk.
Restoration Techniques: * Re-wetting: Raising the water table to recreate anaerobic conditions for Sphagnum mosses. * Damming: Using peat dams, plastic piling, or "leaky" dams to block drainage ditches (grips).
Success Stories: * Forest of Bowland (England): Blocked $40\,km$ of gullies with $3,400$ dams; restored $1,400$ hectares; Sphagnum moss has returned. * West Lussa (Scotland): FLS restored $500$ hectares in a single year by removing trees and blocking drains.

Links and Feedbacks Between Water and Carbon Cycles

Recent Carbon Increases: Fossil fuel emissions doubled from $11$ billion tons ( $1960\text{s}$ ) to $37.4$ billion tons ( $2024$ ). Atmospheric levels at Mauna Loa rose from $316\,ppm$ ( $1959$ ) to over $411\,ppm$ ( $2019$ ).
Energy Budget: $CO_2$ acts as an insulating blanket (enhanced greenhouse effect), trapping heat and disrupting the balance of incoming/outgoing radiation.
Impact on Water Cycle: * Precipitation: Warmer air holds $7\%$ more moisture per $1^\circ C$ of warming; "dry get drier, wet get wetter"; shift from snow to rain. * River Discharge: Flashier peak flows; reduced summer low flows; however, high $CO_2$ can increase plant water-use efficiency, leaving more soil moisture. * Ocean Acidification: Oceans absorb $30\%$ of anthropogenic $CO_2$ , forming carbonic acid and hindering calcifying organisms (corals, shellfish).
Feedback Loops: * Positive (Amplify Change): Permafrost melt releasing methane; Ice-albedo effect (melting ice reveals dark heat-absorbing water); Water vapor trapping more heat. * Negative (Restore Balance): Carbon fertilization (more growth removes $CO_2$ ); increased cloud cover reflecting sunlight; higher ocean absorption of $CO_2$ .
Methane ( $CH_4$ ): Roughly $84$ times more potent than $CO_2$ over $20$ years. Feedbacks include permafrost thaw, wetland expansion, and destabilization of seafloor methane hydrates (clathrates).

Future Implications for Life on Earth

Food Production: Yield instability due to extreme weather; nutritional decline in staple crops (wheat/maize).
Displacement: Low-lying islands and coastal megacities face submersion; hundreds of millions could be displaced by $2100$ .
Diseases: Flooding overwhelms sanitation (cholera); warmer conditions expand habitats for vector-borne insects (malaria, dengue).
Coastal Injustice: Arctic Inuits face "ecological grief" from disappearing ice, loss of ancient cemeteries due to erosion, and food insecurity ( $70\%$ in some regions) as hunting becomes dangerous.

Globalisation and Migration

Global Systems Growth: Expansion characterized by Lengthening (longer travel), Deepening (everyday life connections), and Speeding Up (instant communication via Internet/Apps).
Flows: * Goods: Spatial movement of raw materials and finished products. * Money: Includes Foreign Direct Investment (FDI) and Remittances ( $100$ billion to India in $2022$ ). * People: migration driven by push (poverty/conflict) and pull (work/safety) factors. * Technology & Ideas: Movement of software, hardware, and cultural values (e.g., K-pop popularity).
Globalisation Examples: Global supply chains (Taiwan chips, China assembly), global brands (Coca-Cola, Nike), and international organizations (UN, WTO).
Migration Types: Economic (voluntary for work) and Refugees (forced by persecution). There were $258$ million migrants globally in $2017$ , with a median age of $39$ .

International Migration Patterns and super powers

Contemporary Flows: Movement from China/India/Brazil to UK; workers from South Asia to Gulf States and Saudi Arabia.
Superpowers: Nations able to project power globally. Characteristics include large populations, resources, nuclear weapons, and MNCs. * Hard Power: Force, military action, sanctions. * Soft Power: Persuasion via culture, arts, media. * Smart Power: Combination of hard and soft power.
Global Hubs: Essential cities (e.g., London Canary Wharf, Silicon Valley) with concentrations of MNC HQs and top universities, attracting skilled economic migration.
Migration Conflict & Management: * Brain Drain: High-skilled loss (doctors/IT) impoverishes origin countries while enriching hosts (e.g., USA migration trends). * Backwash: Process draining peripheral regions of young workers to hub regions. * Interdependence: Remittances can account for $40\%$ of GDP in some states. The "Golden Arches" theory suggests interlinked economies are less likely to wage war. * National Policies: Australia's points-based system and "seasonal worker program"; UK's post-Brexit points system prioritizing English fluency and high salaries.

Refugee and IDP Movement Management

Definitions: Refugees are protected by the UNHCR due to "well-founded fear of persecution"; Internally Displaced People (IDP) remain within their country.
Case Studies: * Rwanda: $800,000$ killed in $100$ days; population decline; $2$ million Hutus fled to DR Congo. * Syria: Over $5$ million refugees; $3.6$ million received by Turkey. * Sudan: $2$ million displaced in Darfur due to drought/war. * Ethiopia: Land grabs in the Gambella region displaced $15,000$ for MNC agricultural exports.
International Governance: * UN 1951 Refugee Convention: Establishes "non-refoulement" (refugees cannot be returned to danger). * UNHCR: Guardians of the convention with a $US\$5\,billion$ annual budget. * Peacekeeping: UN troops stationed in areas like DRC since $1999$ ( $30,000$ troops). * NGOs: Amnesty International lobbies the Security Council on groups like the Rohingya.

Global Governance of Oceans

The Global Commons: Shared domains including high oceans, atmosphere, outer space, and Antarctica.
Supranational Institutions: * UNCLOS: Sets rights/regulations; established the International Seabed Authority (ISA). * Exclusive Economic Zone (EEZ): Area reaching $200$ nautical miles from the coast where a nation has economic rights (fishing/oil). * Chokepoints: Strategic narrow channels like the Suez Canal (reduces journey from $20,000\,km$ to $12,000\,km$ ), Panama Canal, and Strait of Hormuz (highest oil movement).
Containerization: Malcolm McLean's innovation revolutionized trade. Maersk operates some of the world's largest ships, contributing $20\%$ of Denmark's GDP.
Submarine Data Cables: $1.5$ million km across $483$ cables; trillions of dollars in daily transactions depend on them. Risks include the Tonga $2022$ volcano break ( $23$ miles offshore) and trawler anchor damage ( $70\%$ of faults).
Sovereignty Conflicts: * South China Sea: Contested by $5$ countries; includes $11$ billion barrels of oil. China uses a "cabbage strategy" to block islands. * Falkland Islands: British territory contested by Argentina (Islas Malvinas). * Bolivia: Lost Pacific coastline to Chile in $1884$ , leading to high transport costs and dependence on neighbors (Arica/Antofagasta ports).

Managing Marine Pollution and Ecosystems

Over-exploitation: Only $1.5\%$ of oceans are protected; technological advances (sonar, factory ships) threaten stocks. Senegal has seen $80\%$ unemployment in fishing industries.
Management Strategies: * No-catch zones: (e.g., Lundy and Lamlash Bay in the UK). * Quotas: EU Common Fisheries Policy. * Marine Conservation Zones (MCZ): $50$ zones in Britain covering over $20,000\,km^2$ .
Ocean Pollution Management: * Eutrophic Dead Zones: Caused by agricultural nutrient runoff. * Plastic: Over $400$ million tons produced annually; gyres (like the Great Pacific Garbage Patch) act as traps. * MARPOL Convention: IMO treaty targeting ship pollution. * EU Single-Use Plastics Directive (2019): Bans straws and cutlery; implements Extended Producer Responsibility (EPR). * Arctic Council: Intergovernmental body including Canada, Russia, and the USA; focus is on environmental monitoring and shipping regulation.