Water and Carbon - Water - Owen Shepherd

Components of Systems

Boundary, input, output, flow

Types of systems

Open, Closed

Boundary relates to?

Energy and Mass movement

Open System

A system in which matter and energy can enter from or escape to the surroundings.

Closed system

A system in which no matter is allowed to cross the boundary, but energy can.

Input (System)

Something that is put in the system; an addition to the components of the system. E.g Precipitation in the Water cycle

Output (System)

is the object, material or idea that a system produces. E.g. river discharge in the water cycle

Flows / Transfers

The links or relationships between the components. Energy and matter can flow between.

Isolated (System)

No energy or matter can cross the boundary. No real application mainly hypothetical.

Positive feedback

Feedback that tends to magnify a process or increase its output. The effect is amplified. Increase leads to further increase

Negative feedback

A process that nullifies the original input or stimulus, causes dynamic equilibrium. Return to a middle ground. Increase leads to decrease and return.

dynamic equilibrium

Flows and processes take place, but in the same way at all times. Leads to small fluctuations but the overall system stays roughly the same - in equilibrium.

Positive feedback (example)

Global temperature rise -> Evaporation rate increase -> Amount of water vapour in air increases -> more solar insulation absorbed -> Global temperature rise

Negative feedback (example)

Co2 in atmosphere increases -> leads to more plant growth -> more photosynthesis -> more co2 absorbed and stored in plants -> decrease in Co2

Residence time

The varying amount of time that matter or energy is stored in a store.

Stores

A place where matter matter or energy is held for a time. E.g. lake in water cycle

Good case studies for Water and Carbon

Amazon Rainforest and River Exe

Five spheres

Lithosphere, biosphere, hydrosphere, cryosphere, and atmosphere. They are cascading systems where water is transferred out of one and into another.

atmosphere

The store of x within the air that surrounds our planet

hydrosphere

The store of x located in any water that is not frozen for example in our rivers, oceans, lakes, and seas

Biosphere

The store of x in the zone of the living things on the planet

Lithosphere

The store of x in the rock shell of the earths surface. E.g. Aquifers

Cryosphere

The store of x in all frozen forms of water. E.g. Glaciers and ice sheets.

How much water is oceanic?

97%

Ocean Acidification

decreasing pH of ocean waters due to absorption of excess atmospheric CO2 from the burning of fossil fuels.

ocean acidification Change

8.25ph -> 8.14 ph

Cryosphere components

Sea ice, Permafrost, ice caps, ice sheets, alpine glaciers

Ice caps vs Ice sheets

Ice caps are continental sized ice sheets. Defined as ice cap not sheet if over 50,000km2.

Consequence of Ice melt

Sea level rise, freshwater store is released into sea (saltwater), 99% of freshwater could be lost.

Extent of sea level rise

Anywhere from 6 to 60 metres in rise.

Sea level rise why?

Heat up sea = expansion of water, more water in sea due to melting, or due to human activities.

Permafrost

Remains below freezing for all year 24/7, defined by if it remains frozen for 2 years straight.

Permafrost melt consequences

More water released into sea - sea level rise. Co2 and METHANE!! stored in permafrost bubble - released into atmosphere and contributes to GW. Leads to further permafrost melt.

terrestrial

relating to the land, located on the land.

4 types of terrestrial water

Surface water, groundwater, soil water and biological water.

Wetland importance

Huge dominance of vegetation, store loads of water and Co2, aids water purification, climate stabilisation, global biodiversity

Wetland example

The pantanal

Surface water

Water above the surface of the land, including lakes, rivers, streams, ponds, floodwater, and runoff.

Groundwater

water that fills the cracks and spaces in underground soil and rock layers. W.g. Aquifers.

Soil water

Moisture in the soil

Biological Water

water stored in all biomass

Groundwater over abstraction

Overusing the process of taking water from a ground source. Takes decades to fill back up, used up much faster. Leads to water running out unless it can be quickly recharged. Disrupts the water cycle equilibrium

Soil water importance

Fundamental to biological processes. Need water to live, controls flooding and exchange of water and heat to soil.

Water vapour

water in gas form

Water vapour role

Greenhouse gas, absorb reflect and scatter solar insolation / radiation. Keeps world temp stable - greenhouse effect contribute.

Positive feedback - water vapour

Heat up -> more evaporate -> more water vapour -> more solar insolation absorbed -> enhanced greenhouse effect -> heat up.

Type of water cycle vs scale

Global = closed, local = open

Overall water = oceanic %

95%

Of that freshwater how much = frozen

79%

Of that freshwater how much = groundwater

20%

So how much water is drinkable

1% of 2.5% of the global supply, 0.025%, with 38% of that drinkable water not being in the hydrosphere

Aquifer distribution

Common in Europe and South America. Some in North America and North Africa

Aquifers store water what % of freshwater wordwide?

30% of freshwater worldwide

Why aquifers some places not others

Soil and rocks vary dramatically in their ability to store water

Water table

The upper level of the saturated zone of groundwater

Why do humans disrupt aquifer equilibrium

More out than in, takes thousands of years to re fill

Albedo effect

the positive feedback loop in which an increase in the Earth's temperature causes ice to melt so more radiation is absorbed by the Earth's surface leading to further increases in temperature and therefore further ice melt. It has the same effect the other way round, more ice, more insolation reflected, less insolation absorbed, more ice.

Key terms for Albedo

Accumulation and Ablation, in terms of the change in ice levels

Albedo effect leads to overall?

Too far into one of them could lead to the disruption of the Dynamic Equilibrium. Lead to big consequences, ice age or heat death. Also huge effects on where and how water is stored.

Changes of matter

Evaporation and condensation, sublimation and deposition, melting and freezing.

Magnitude of water stores varies over?

Temporal and Spatial scales - time and place

Overall water that = freshwater %

2.5%

4 main drivers of change in the water system

Evaporation and condensation rates, Climate Change, Cryospheric Processes, Cloud formation and change in Precipitation.

Evaporation transfers water?

To the atmosphere

Evaporation rates depend on:

Humidity, Wind, Temperature, Sunlight and Daylight, Surface area of Water exposed

Condensation role

Water condenses into liquid from gas after evaporating in the atmosphere, it then falls as convective rainfall

Dew point temperature

The air cools to its saturation point, cannot hold any more water at that temperature, its temperature is too low it does not have enough internal energy to store that water as a gas, all the water stored as a gas rapidly condenses.

adiabiatic cooling

rising air decreases in pressure and expands in volume, uses up the internal energy to expand and push out on the other air, cools the temperature of the air, and then leads to condensation of that air as it has cooled, energy decrease and water condenses. Happens when Pressure goes from high to low.

Climate change vs Anthropogenic Climate Change

CC is natural, anthropogenic CC is caused by humans

Climate change

Maintained by the greenhouse effect, ruined and expanded due to the HUMAN ENHANCED greenhouse effect, leads to excess global warming, which leads to CC

Consequences of Climate Change

melting ice caps, rising sea levels, extreme weather, drought, flooding, increased extinction rates, habitat loss

Milankovitch cycles - what are they?

Eccentricity, Obliquity, Precession

Milankovitch cycles definition

Changes in the shape earth's orbit and tilt that cause glacial periods and interglacial periods.

Eccentricity

The oval shape of the earth orbit, not perfectly circular, close = more solar isolation, further = less, drives glacial vs interglacial, longest timescale up to 400,000 years between variation

Obliquity

The tilt of the Earth's axis, varies between 22.1 and 24.5 degrees, over a ~40000 year time period, controls how extreme the seasons are, greater tilt = more extreme, huge effect on long term CC and Glacial Cycles.

Precession

Wobble in Earth's rotational axis, around ~20000 year time period, shortest one, works in effect with eccentricity, in a pattern together, determines which hemisphere gets the hotter or colder set of seasons?

Cryospheric processes

The Albedo effect -> Glacial and Interglacial periods. Amplify or nullify the effect of the sun.

Ice damming

Ice build up blocks a valley and creates temporary lake, water transferred to the Hydropshere

Cloud formation

Rising of warm air, carries water up in it, air cools and water condenses, condenses and forms / sticks to Condensation Nuclei contained in Aerosols, Droplets keep growing and combine, cloud, fall as rain

What causes condensation of water in the air?

As it rises through the atmosphere, cools down and expands, effects of both adiabatic cooling and reaching the dew point lead to condensation

Types of rain

Relief / Orographic, convective, frontal

Relief/Orographic Rainfall

Rainfall formed due to warm moist air being forced to rise by the relief of the land. Once risen, the air cools, expands and condenses (due to effects of dew point and adiabatic cooling) forming cloud and then fall as precipitation.

Frontal Rainfall

When a warm air mass meets a cold air mass, don't mix as different densities, warm rises over the cold, as warm rises, cools and expands, condenses due to dew point and adiabiatic cooling, forms clouds and then falls as precipitation. Falls along the line where the two fronts meet.

Convective rainfall

Simplest type, heat ground, evaporate and warm up, rise, cool and expand, condense due to dew point and adiabiatic cooling, form cloud and fall as precipitation

Global Circulation model

Theory explaining how the atmosphere operates in three cells either side of the equator. All differently heated so have different low / high areas of pressure. Drives this theory

Cells in Global Circulation Model - From Equator

Hadley, Ferral, Polar

drainage basin

the area from which a single stream or river and its tributaries drains all of the water. A small scale example of the water system

Drainage basin in / out

Input: Precipitation, Output: River Discharge, Evaporation, Transpiration, Evapotranspiration

Drainage basin - underground flows

Throughflow, Baseflow, groundwater flow, infiltration, percolation

Throughflow / Interflow

Water flowing through the soil layer parallel to the surface

Groundwater flow

Water that is flowing beneath earths surface

Baseflow

Groundwater flow that feeds into rivers through river banks and river beds.

Difference between groundwater flow and Baseflow

Baseflow is groundwater flow when it enters a river through the banks or ground.

Other flows in a drainage basin

Stemflow, Throughfall, Transpiration, Evaporation, Evapotranspiration, River Discharge, Precipitation, Surface run off

Stem flow

When intercepted water runs down the trunks and stems of vegetation.

Throughfall

Water that reaches the ground either directly or after being intercepted by vegetation. E.g. Drips off of the leaves

Surface run off

Water flowing on top of the ground

Stores in a drainage basin

Interception, Soil Water, surface water, groundwater, channel storage and vegetation storage

Channel Storage

Water held in a river or stream channel

Interception

Water being prevented from reaching the surface by trees or grass