combined: all* of ELSS for end of years

icl i removed some stuff that i js quite simply didn't wanna revise... like lapse rates and clouds and stuff. so if it comes up in the exam, uhhh sad times ig

How much of Earth is oceans?

71%

Why is water importance in supporting life for humans

Water is fundamental for life on Earth because it helps transport blood, oxygen etc in our bodies, enables chemical reactions, regulates our internal temperatures, and protects organs. This allows us, humans, to survive during our daily life

Why is water important for supporting Earth

It is important for Earth it creates habitats for animals, stabilises ecosystems and reduces droughts, and drives the water cycle which provides water and life for different species

Water's importance in keeping earth at a suitable temperature

Clouds made up tiny water droplets and ice crystals reflect 1/5 of incoming solar radiation, lowering surface temps. Water vapour absorbs long wave radiation from the Earth's surface, helping to maintain average global temperatures

Uses of water for fauna (4)

• Animals rely on water to regulate internal body temperature, via processes such as sweating and panting. For example elephants spray water on themselves. • Water bodies like coral reefs and rivers act as breeding grounds, shelter, and feeding sites for many species. • Large oceans and rivers act as corridors for seasonal migration for species like salmon, whales. • Water is used to circulate energy and nutrients through the animal's body. Then animals return the water to the environment via excretion

Uses of water for flora + impacts (4)

Plants need water for photosynthesis, which provides them with food, allowing them to survive. Plants require water to maintain their rigidity and to transport mineral nutrients from the soil. By transpiration, the plant thermoregulates, ensuring it keeps a good internal temperature, preventing thermal damage. Water controls the opening and closing of stomata. When the stomata open, carbon dioxide is taken in by the plant, allowing photosynthesis to happen

Describe carbon

Carbon is one of the most abundant chemical elements on Earth. It is important as it can bond with many other elements. Carbon forms the basis of 95% of all known compounds

Why is carbon considered the building blocks of life

Carbon forms complex molecules like carbohydrates, proteins, and lipids. These are essential for all living organisms

Where is carbon stored on earth

Atmosphere, oceans, soils, rocks, and in living organisms

How do plants use carbon

Plants photosynthesise, utilising carbon dioxide from the atmosphere to use as nutrients. Algae and other organisms remove carbon from the atmosphere, maintaining a necessary carbon balance for a habitable planet. Plants also respire, moving carbon from the biosphere to the atmosphere

How do animals use carbon

They consume it by feeding on plants or other animals. They return it to the atmosphere through respiration, excretion and decomposition

How do humans use carbon

For fossil fuels so they can use it for oil and natural gas. In every day life e.g. plastic packaging, graphite pencils. Mainly for energy generation e.g. power plants, vehicle fuel

How does water move between the land, oceans, and atmosphere

Water evaporates from oceans, lakes, and rivers → condenses into clouds → precipitates over land or ocean → infiltrates soil or flows as runoff back to rivers → returns to oceans

What are the main stores of water at the global scale

Oceans (largest), land (rivers, lakes, soil, glaciers), and atmosphere (smallest)

How can humans impact the water cycle

Dams, irrigation, and groundwater extraction can alter natural flows, reduce water availability, and disrupt ecosystems

How does carbon move between land, oceans, and atmosphere

Plants absorb CO₂ through photosynthesis → converted to biomass → eaten by animals → returned to atmosphere via respiration, excretion, or decomposition. Oceans absorb CO₂ → some stored in deep water or sediments

What are the main carbon stores on earth

Sedimentary rocks/fossil fuels (long-term, 99.9%), oceans, soil, atmosphere, and living organisms

How do humans affect the carbon cycle

Burning fossil fuels and deforestation transfers carbon from long-term stores to the atmosphere → increases CO₂ → enhances the greenhouse effect → climate change

How is the global carbon cycle an example of a closed system

Carbon cannot leave Earth, so it continuously cycles between atmosphere, oceans, soils, rocks, and living things, even though energy from the sun drives the cycle

How are the water and carbon cycles connected

Water availability affects plant growth → photosynthesis → carbon uptake. Plants also return moisture to the atmosphere through transpiration → influences local climate

Where is most water stored

97% is stored in the oceans

Where is non-ocean water stored

In the cryosphere - ice caps, glaciers etc. high altitude and high latitude. Aquifers. In terrestrial water stores - rivers, wetlands, lakes. Atmospheric water - water vapour

Are stores of water evenly distributed around earth?

Water stores are not evenly distributed. Less than 10 countries possess 60% of the world's freshwater supply

Describe aquifers

30% of all freshwater is stored in aquifers. These aquifers are most commonly formed by chalk and sandstone

What is interception

When vegetation intercepts a proportion of precipitation, it stores it temporarily on branches, leaves, and stems. Some of this moisture evaporates straight back into the atmosphere whereas some falls to the ground

Explain the 4 factors affecting interception loss

Interception storage capacity -> interception is dependent on the duration and intensity of a rainfall event. Wind speed -> rates of evaporation will increase with wind speed. Vegetation type -> trees have greater interception loss than grasses because they have higher surface area. Tree species -> interception loss is greater from evergreen trees

What is infiltration

The process by which water soaks into the soil surface. Water moves slower in the soil than it does on the surface of the earth

What is throughflow

When water is in the soil, gravity forces water to move downhill as throughflow towards stream and river channels

What is percolation

Some water moves deeper into rocks by percolation

What is groundwater flow

Gravity moves water towards channels via groundwater flow

What is the water table

The boundary between saturated and unsaturated conditions underground

What is run-off

All the water that drains from an area is known as run-off. This process is multiscalar

What is water balance

The balance between inputs and outputs to a drainage basin

When does a water surplus occur

When there are storms, excessive rainfall, floods, or glaciers melting

What is field capacity

The amount of water held or retained in soil after excess water has been drained freely due to action of gravitational forces

What is a drainage basin

Area of land drained by a river and its tributaries

Inputs, stores, processes, and outputs of a drainage basin

Inputs - Precipitation, snowmelt. Stores - interception, soil, lakes, rivers. Processes - stem flow, surface runoff, infiltration, percolation. Outputs - evaporation, transpiration

What factors affect evapotranspiration

Temperature – higher temperatures increase rates. Wind speed – removes moist air, increasing evaporation. Humidity – low humidity increases evapotranspiration. Vegetation type – more vegetation increases transpiration

What is river discharge

The volume of water flowing in a river channel per unit time. It transfers water from land back to the oceans - important in water cycle

How does river discharge vary

Seasonally – higher in winter, lower in summer. During storms – rapid increase due to surface runoff

What are cryospheric processes in the water cycle

Freezing – water turns into ice. Melting (ablation) – ice turns into water. Storage of water in glaciers and ice sheets

Why is the cryosphere important in the water cycle

Acts as a long-term store of water. Releases water seasonally through melting

Porous vs pervious rocks

Porous = Water occupies pores or cavities eg. Chalk/Sandstone. Pervious = Water moves along joints and bedding planes eg. Carboniferous limestone

What is infiltration excess

Infiltration excess is when heavy rainfall means that soil cannot absorb water quickly enough, leading to overland flow and possibly flooding

What is saturated overland flow

Prolonged rainfall fills soil. Soil too saturated, so becomes impermeable. Water cannot infiltrate. Surface runoff takes place.

How is water recirculated within the water cycle (3)

Ocean -> land -> ocean. Eg, the Atlantic ocean transfers water from the ocean to North America, South America, Africa, and Europe. Recirculation of water over land. Eg, water transpires from plants into the atmosphere. Ocean -> ocean. Eg, the Pacific ocean only really transfers water within the Pacific

What is dew point

The temperature the air needs to be cooled to (at constant pressure) in order to achieve a relative humidity of 100%

What are clouds and how do they form

Clouds are visible aggregates of water or ice (or both) that float in the free air.
They form when moist air cools

Role of clouds

Control our global climate
Absorb long-wave terrestrial radiation, warming the planet
Contribute to the natural greenhouse effect, keeping our planet warm enough for life to be sustained
Reflect short-wave radiation back out to space, cooling the earth

How can cooling occur (4 ways)

Convection
Advection
Orthographic lift
Frontal uplift

What is adiabatic expansion

As air rises, air pressure falls
This means air expands
All the molecules spread out, leading to cooling
As it cools to dew point, condensation occurs

Describe orthographic lift

Orthographic lift - when air is forced to rise over a range of hills or mountains. If sufficient cooling occurs, condensation takes place

How does convection lead to the formation of clouds (exam question)

Sun begins to heat up the earth
Warm air rises
As it rises, it expands and cools
Reaches saturation point where humidity is 100%
Condensation starts to occur
When water condenses, it goes from gas to liquid --> forming a cloud

Cirrus clouds

Weather - fair
Appearance - wispy streaks
Requirements to form - low temps and high water vapour

Stratus clouds

Weather - dull, overcast,drizzle
Apperance - flat and featureless
Requirements to form - high altitude and high humidity

Cumulus clouds

Weather - fair, bright, sunny
Appearance - puffy white
Requirements to form - low pressure + water vapour

What is the carbon cycle

The carbon cycle is the continuous movement of carbon between different stores in the atmosphere, biosphere, lithosphere, and hydrosphere. It is a closed system where carbon moves through stores via processes like photosynthesis, respiration, diffusion etc. There are two types of carbon cycle - fast and slow.

Plants' role in the carbon cycle

Plants = release carbon dioxide and dies, meaning it is part of the fast carbon cycle. Carbon is constantly being exchanged between plants and the atmosphere.
Respiration by plants and animals + decomposition of dead organic material returns CO2 to the atmosphere

Rocks' role in carbon cycle

Rocks = sequester carbon for a long time therefore part of the 'slow carbon cycle'
They can sequester carbon for up to 150 million years
When they are chemically weathered by acid rain, the carbonate materials are attacked. This releases CO2 into the atmosphere

What is the role of oceans in the carbon cycle

The oceans and atmosphere exchange carbon with CO2, dissolving in surface water. A return flow of CO2 occurs via evaporation

How is the ocean's role changing due to climate change

When carbon is absorbed into ocean water it makes oceans more acidic
We rely on the oceans to store carbon otherwise the global avg temp would be a lot water
But the issue is that cold oceans are more effective at dissolving carbon, but global warming is making our oceans hotter so the process is getting less efficient

The role of precipitation in the carbon cycle

Carbon dioxide can be dissolved in rainwater to form weak carbonic acid
Carbon then flows back into the oceans and land when precipitation happens

How is precipitation's role changing because of climate change

This natural process is being affected by the rising concentrations of CO2 in the atmosphere -> the rain's acidity is increasing because of climate change

How does decomposition play a role in the carbon cycle

Fungi and bacteria return CO2 to the atmosphere
Decomposition also produces soluble organic compounds dissolved in run-off from the land surface
GHGs are released as a by-product

Combustion's role in the carbon cycle

Fossil fuels contain carbon captured by living organisms over millions of years
Since the industrial revolution, these fuels have been mined and combusted to serve as a primary energy source. The main by-product of fossil fuel combustion is CO2

Weathering's role in the carbon cycle

Weathering processes break down rocks on the earth's surface
These small particles are combined with plant and soil particles and carried to the ocean
Large particles are deposited on the shore and the sediment accumulates
Within the ocean, dissolved sediment mixes with seawater and are used by marine organisms to make skeletons and shells containing calcium carbonate
When these organisms die, carbonate collects at the bottom of the ocean and sedimentary rocks (e.g. limestone) form

Positive feedback in the carbon cycle

human activity releases CO2 into the atmosphere so it warms up. This warmth triggers natural processes like melting ice or soil decay, which releases CO2, causing warming. This continues on and on. An example is permafrost thawing. When permafrost melts, bacteria decomposes ancient organic matter stored in the permafrost. This releases greenhouse gases via the process of decomposition. This causes more warming and more melting.

Negative feedback in the carbon cycle

there are two examples of negative feedback. Firstly, when CO2 levels increase in the atmosphere this allows plants to photosynthesise. This makes plants grow faster and larger, sequestering more carbon. This removes some of the excess CO2 from the atmosphere. Secondly, increased CO2 leads to a warmer, wetter climate. Rainfall reacts with CO2 to form carbonic acid. Acid rain weathers rocks, and a chemical reaction that captures carbon occurs, washing it into the ocean, where it is sequestered for many years.

What is carbonation (chemical weathering)

CO₂ dissolves in rainwater to form carbonic acid
This reacts with carbonate rocks (e.g. limestone)
Carbon is removed from the atmosphere and stored

What is hydrolysis (chemical weathering)

Carbonic acid reacts with silicate minerals
Forms clay minerals and dissolved ions
Removes CO₂ from the atmosphere

Why is chemical weathering important in the carbon cycle

Acts as a long-term carbon sink
Transfers carbon to oceans and sediments

Where does natural carbon sequestration occur

Oceans – CO₂ dissolves in water
Vegetation – photosynthesis stores carbon
Sediments – carbon buried long-term
Weathering – removes CO₂ from atmosphere

What does the water cycle look like in the Arctic Tundra?

Limited groundwater and soil moisture – permafrost is a barrier to infiltration, percolation and groundwater flow.
Low annual precipitation (50-350mm) with most falling as snow
There are extensive wetlands, ponds and lakes on the tundra during the summer. Temporary store of water impedes drainage as it lays on top of the permafrost.
There are small stores of moisture in the atmosphere owing to low temperatures which reduce absolute humidity.
Low rates of evaporation. Much of the suns energy in the summer is spent melting snow so ground temps remain low and surface and soil water are frozen for most of the year.

What does the carbon cycle look like in the Arctic tundra?

Carbon is mainly stored as partly decomposed plant remains frozen in the permafrost
Most of this carbon has been locked away for the past 500,000 years
Permafrost is a vast carbon sink estimated to hold 1,600GT of carbon. This is due to the low temperatures which slow the decomposition of dead plant material.
NPP (net primary productivity – the amount of new growth in a given area per year) is low due to the short growing season.
The amount of carbon in tundra soils is 5x greater than the above ground biomass.
During the growing season, plants input carbon rich litter to the soil and decomposition increases releasing CO2 into the atmosphere through the respiration.
Even in the winter, there are pockets of unfrozen soil and water, which release CO2 and CH4.
Snow cover can insulate microbes, which slow decomposition.
Limited transpiration because of the sparseness of vegetation and the short growing season.

How does temperature affect flows and stores in water cycle in the Arctic tundra

• Most of the year, water is stored as ground ice in the permafrost layer because of freezing temperatures
• During the short summer, the shallow active layer thaws and liquid water flows on the surface, forming pools and shallow lakes made of meltwater
• In winter, sub-zero temperatures prevent evapotranspiration
• In summer, some evapotranspiration occurs from standing water and saturated soils
• Humidity is low all year around, and precipitation is sparse

How does rock permeability and porosity affect flows and stores in water cycle in the Arctic tundra

• Permeability is low because of the permafrost and crystalline rocks which dominate the geology of the Arctic tundra
• Drainage is low because permafrost is impermeable
• The frozen ground means the porosity is very low in winter; in summer the thawed active layer because saturated quickly because water can't percolate deeper

How does relief affect flows and stores in water cycle in the Arctic tundra

• Minimal relief and erratic glacial deposits causes slow drainage, which increases waterlogging in summer months
• The ancient rock surface which underlies the tundra has been reduced to a gently sloping plain by millions of years of erosion and weathering
• Flat relief and impermeable permafrost means there are lots of thermokarst lakes in the summer, resulting in massive temporary stores of standing water

How does temperature affect flows and stores in carbon cycle in the Arctic tundra

• Waterlogging of the soil and low temps means slow decomposition and respiration
○ Because the decomposition rates are low, this means the tundra is a carbon sink
• Low temperatures, unavailability of liquid water for most of the year, and soils containing few nutrients are all factors that limit plant growth
○ This means the total store of carbon in the biomass is small
• Photosynthesis is low so there isn't much carbon being absorbed

How does organic matter in the soil affect flows and stores in carbon cycle in the Arctic tundra

• During the growing season, tundra plants input carbon-rich litter to the soil
• Microbial activity increases, releasing CO2 to the atmosphere via respiration
• Low temperatures and waterlogging slow decomposition, respiration, and the flow of CO2 in the atmosphere
• When organic matter decomposes in waterlogged soil, this is anaerobic, causing methane to be released too.
○ This has a negative impact on global warming because it’s a ghg

How does mineral composition of rocks affect flows and stores in carbon cycle in the Arctic tundra

• The tundra is underlain by ancient crystalline rocks e.g. granite
○ These contain very little organic carbon compared to sedimentary rocks
○ Chemical weathering is slow, because carbonation requires liquid water and heat - both of which are sparse in the tundra

How does vegetation affect flows and stores in carbon cycle in the Arctic tundra

• There is not much vegetation in the Arctic tundra because few plants have adapted to the extreme environment of the High Arctic
• In the Low Arctic the conditions are less severe so there is continuous ground cover of vegetation
• In the tundra the biomass carbon store is small because vegetation is so limited
• In the summer plants can photosynthesise but only for a very short time

How do seasonal changes affect the water cycle in the Arctic tundra

• In the summer, some evapotranspiration occurs from standing water, saturated soils, and vegetation.
○ Active layer of the permafrost thaws, but the ground below remains frozen, so meltwater has to stay on top, forming thermokarst lakes
• In the winter the water is all locked away as frozen soil in the permafrost

How do seasonal changes affect the carbon cycle in the Arctic tundra

• In the summer there is more microbial activity, so more CO2 is released via respiration.
○ Mosses and lichens rapidly photosynthesise and the tundra becomes a carbon sink, but soil microbes also decompose organic matter which releases CO2
• In the winter the temperatures are low and there is waterlogging, which slows respiration so less CO2 is released

Strip mining in the Arctic tundra

Alaska possesses roughly half of the coal reserves in the USA
To access it, strip mining occurs
This disturbs the equilibrium of stores and flows as the removal of sediment means less infiltration can occur, forming talik at the surface

Methane's impact on arctic tundra

Methane is 20x more potent than CO2. methane is a bi-product of some animals' digestion. This methane gets stored in the ice as bubbles. When the ice thaws in spring, the methane will escape.

Impact of strip mining on water cycle

• Strip mining creates artificial lakes (taliks) disrupting drainage and leads to further melting
• Strip mining disturbs equilibrium of stores and flows as the removal of sediment means less infiltration can occur, so taliks and pools of water are created
• The melting of permafrost means increased surface run-off and higher river discharge, hence increased flood risk

Impact of strip mining on carbon cycle

• Removal of peat and topsoil releases long-stored organic carbon
• Exposed darker soil absorbs more solar energy (-> less albedo), accelerating thawing and carbon release
• Anaerobic decomposition in mining pools releases methane, a more potent greenhouse gas
• Mining releases carbon that has been stored underground for years
• Heavy machinery used in strip mining process causes fossil fuel consumption and releases CO2
• The removal of tundra also means less carbon is sequestered in the biosphere
• Dust generated from mining settles on the snow, reducing albedo -> accelerates permafrost melting

Impact of oil and gas drilling on water cycle

• Quarrying also interferes with permafrost and natural drainage systems
• Drilling creates 40,000m3 of oily waste per well, which has to be disposed of via sand and gravel pits. Waste may seep through the pits and into water supplies
• Oil and gas production, which can cause localised melting of the permafrost and snow cover, thus increased run off and river discharge

Impact of oil and gas drilling on carbon cycle

• Flaring the gas releases methane, which is more than 20x more potent than CO2 → positive feedback loop
• Soot from gas flaring settles on snow, reducing albedo and accelerating melting
• Permafrost thaws from drilling activities, causing melting and positive feedback loop
• Construction destroys vegetation, which decreases photosynthesis and limits the removal of CO2 from the atmosphere

Impact of Trans-alaskan pipeline on water cycle

• The active layer melts creating meltwater pools. In these pools, decomposition is often anaerobic meaning it produces methane.
• Activities (e.g., construction, dust deposition and vegetation removal) caused lowering of albedo and localised melting of the permafrost -> increases surface run-off and river discharge -> increasing flooding
• In summer wetlands, ponds and lakes increase in extent, increasing rates of evaporation. Removal of vegetation reduces transpiration.

Impact of Trans-Alaskan pipeline on carbon cycle

• Organic matter from many years ago is exposed when the permafrost melts (as a result of heat from oil in the pipeline). This matter decomposes, releasing co2 into the atmosphere, leading to a positive feedback loop and increased temps
• Vegetation is removed to build the pipeline, which reduces the sequestration of carbon due to decreased photosynthesis
• Infrastructure to build and maintain pipeline releases CO2

What is the purpose of using insulated ice pads and roads in the Arctic?

• Method: Temporary roads/pads built from frozen water during winter for transport and drilling.
• Water Cycle: Protects the active layer and vegetation from compaction; prevents the formation of meltwater pools (taliks) that disrupt drainage.
• Carbon Cycle: Prevents damage to vegetation (carbon sequestration) and stops the soil from warming/releasing CO2 or methane.

How do gravel pads manage the impact of oil and gas infrastructure?

• Method: Placing buildings/roads on layers of gravel 1.5m–2m thick.
• Effect: Acts as an insulator.
• Cycle Link: Prevents heat transfer from human activity to the permafrost. This keeps the carbon store locked in the ground and prevents the positive feedback loop of methane release caused by localized melting.

Why is the Trans-Alaskan Pipeline elevated on stilts

• Method: Elevating infrastructure on metal stilts driven into the permafrost.
• Water Cycle: Prevents the warm pipe/building from melting the ice below, maintaining natural surface drainage patterns.
• Carbon Cycle: Allows cold air to circulate beneath, keeping the permafrost frozen and the organic matter stable (preventing anaerobic decomposition).

What is dynamic equilibrium

A state of long-term balance in a system that has variable inputs, stores, flows and outputs

What does dynamic equilibrium look like in the water cycle

In the drainage basin, an increase in water input will lead to more water entering the stores
If these overflow, the river levels rise and flooding may occur
Eventually the rain stops and the river discharge decreases
Floods recede and the drainage basin reverts to pre-storm state

What does dynamic equilibrium look like in the carbon cycle

At the global scale, some increase in atmospheric CO2 can increase rates of photosynthesis
Plants therefore grow vigorously and store carbon in their tissues
This feedback decreases the quantity of CO2 in the atmosphere and a state of dynamic equilibrium is achieved

Example of negative feedback loop (global temps rising)

Global temps increase
More evaporation
Increased water vapour in atmosphere
Increased cloud cover
More incoming solar radiation is reflected back into the atmosphere
Global temperatures fall

Example of positive feedback (global temps rising)

Global temperatures increase -> decomposition of organic material speeds up -> more CO2 is released into the atmosphere -> more of the sun's rays are trapped -> global temperatures rise

How does urbanisation impact the carbon cycle

• Urban areas have a high concentration of vehicles and industry, resulting in massive CO2 emissions
• Construction in urban areas requires concrete, which uses heat from fossil fuels and calcination, releasing more CO2 into the atmosphere
• Urban areas replace biomass when trees are cut down to make space for other urban uses e.g. car parks, stopping carbon from being sequestered
• Eutrophication happens from fertiliser use, causing algal bloom which results in decomposition and lots of CO2 and methane being released from bodies of water
• Impermeable concrete means organic matter cannot enter the soil, stopping it from storing carbon