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Carbon Cycle Notes

20190722 Notes / from Mike Weintraub, carbon cycle, youtube video https://www.youtube.com/watch?v=nzImo8kSXiU

One of the most important elements on earth

One of the most abundant elements period

All earth life is based on carbon

carbon is contained and moved from one state and place to other states/places -- this is the carbon cycle

human activities are releasing all these different stores of carbon (forests, plants, soil, fossil fuels) into airbone CO2

Atmosphere is a small carbon sink, roughly 1% of the earths carbon pool. But, since its not that much, we can easily change it by disrupting other aspects of the carbon cycle (like releasing a bunch from below ground via burning fossil fuels or crappy land managment practice)

Disturbing the other stores/systems releases more to the atmosphere and that rapidly has a drastic, immediate, & lasting affect (effect?)

drop of food coloring in a cup of water versus a pool of water... as illustration?

plants/trees take their carbon from the atmosphere. photosynthesis

the main issue is that we keep adding more to the atmosphere without taking some out -- plants use what we normally respirate; but if we're unearthing carbon from ground and below ground stores its too much too fast.

20190722 BBC.com Material Cycles in Ecosystems https://www.bbc.com/bitesize/guides/zg9v6yc/revision/2

Carbon is in everything on earth (pretty much)

Carbon eneters the atmosphere as CO2 from respiration and combustion (decomposition is also a form of respiration)

Photosynthetic plants take CO2 from the air and use that C to grow, release the O2 back to the atmosphere.

Photosynthesis builds carbohydrates for plants to use for their life processes. Mostly in the form of Glucose. How that works, well, that's another presentation for a different class... or for your own research...

There is a sub cycle, less CO2 in northern hemisphere summers, more in winters due to northern boreal forests growing and then losing foliage for the winter...

  1. carbon enters the atmospher as CO2 through respiration and combustion.
  2. carbon is absorbed as CO2 by plants through photosynthesis; used to make glucose (C + H20 = carbohydrates)
  3. Animals + other organisms eat plants moving some of that carbon into their bodies (moves along the foodchain). We mainly then exhale out the carbon we've taken in from eating as CO2 -- Aerobic respiration.
  4. Animals, insects, microbes, and plants all eventually die. Decomposition breaks down the dead matter returning more C to the atmosphere as CO2 (microbe respiration also releases CO2). However, somtimes decomposition is blocked and the plant or animal matter gets buried -- this sequesters this carbon, containing it underground or underwater. This might eventually turn into sedimentary rock or into fossil fuels.
  5. When/If we unearth fossil fuels and burn them, combustion causes that carbon to become CO2 in the atmosphere.

20190722 Khan Academy Carbon Cycle Class https://www.khanacademy.org/science/biology/ecology/biogeochemical-cycles/a/the-carbon-cycle

Fast and slow processes

Fast are all the regular life processes -- these turn carbon from one form to another in minutes, days, weeks, or years... (respiration, decomposition, combustion)

Slow are the geological processes. like the forming of rocks and fossil fuels. These take decades, centuries or millenia.

20190725 Hugh Pocock Carbon Lecture http://climatechangeandsustainability.edublogs.org/lectures/

CARBON CYCLE

Q. What is Carbon?

A. Carbon is the 4th most abundant element in the universe (Hydrogen, helium, oxygen, carbon)

Q. Where did it come from?

A. Comes from meteorites that bombarded the planet as it was forming billions of years ago

Q. What does it do?

A. Carbon anchors all organic substances, it is a polymer, it binds things together, forms chains, helps things get organized, is basis for all life

Carbon plus hydrogen make hydrocarbons, equals fossil fuels equals crude oil, gasoline,kerosene

When combined with oxygen and hydrogen, carbon can form many groups of important biological compounds including sugars, celluloses, lignans, chitins, alcohols, fats, and aromatic esters. With nitrogen it forms alkaloids, and with the addition of sulfur also it forms antibiotics, amino acids and proteins. With the addition of phosphorus to these other elements, it forms DNA and RNA, the chemical codes of life.

Makes hardest material and softest, diamond and graphite

Q. Where is it found?

A. It is found in all living things, also in the atmosphere and in limestone layers in ocean also in all fossil fuels (coal,oil)

Q. What is CO2?

A. Carbon plus oxygen make carbon dioxide, Co2 is essential for biological life

Q. What does CO2 in the atmosphere do?

A. Our atmosphere is the envelope around our planet where energy from the sun is temporarily stored, giving us the temperatures necessary for life. Co2 along with methane and water vapor are termed greenhouse gases as they are semi opaque gases that allow for the suns energy in the form of visible light to enter the atmosphere but partially block it after it bounces off the earth’s surface in the form of heat. The balance of what is allowed into the atmosphere and the amount that is allowed back out is what determines the atmospheres temperature. In particular the Lower Atmosphere where we live. The higher concentration of greenhouse gases, the more heat confined to the atmosphere.

Q. What is the “Carbon cycle”?

A. With our current understanding of the earth’s dynamics the carbon cycle is the way that we observe carbon cycling through the planets interconnected systems.

The total cycle has within it two systems that operate at different time scales, these are the Geological and the Biological.

Geological Carbon Cycle: millions of years

Carbon is present from the forming of the planet, (bombarding meteorites) H2o and CO2 in the atmosphere form to make a weak acid that releases the carbon from exposed rock and washes it into the ocean where it settles onto the seabed. With the movement of the earth’s crust it is then drawn back into the earth’s mantle through subduction, where it becomes magma, through volcanic eruptions is released again as CO2, volcanic gas and lava. This system regulates amount of atmospheric carbon dioxide which in turn contributes to the regulation of the earth’s temperature. Over the course of the earth’s history this cycle has varied in intensity , this variable is thought to be a contributing factor in the oscillation of ice ages and periods of warming or deglaciation

Biological: days,thousands of years,

photosynthesis is the foundation of the biological carbon cycle system, through photosynthesis plants combine solar energy and co2 into sugars or carbo hydrates, this is the energy of cell division…growth

the “burning” of these carbohydrates is called respiration through which CO2 is released back into the atmosphere.

It is biologically fixed CO2

Plants inhale and exhale CO2, but far greater percentage of the CO2 is sequestered in the biological cycle by being stored in living and dead plant matter, roots, in the soil, eaten by animals (us to). In the oceans CO2 is stored in phytoplankton, clamshells these settle to bottom and form limestone, sediments,fossil fuels this is one place where the biological and the geological carbon cycles interconnect

Photosynthesis and respiration provide both a daily and annual fluctuation in co2 levels

We can look at both the biological and geological as a vast unified carbon regulator, a system the absorbs and releases carbon at different rates over different periods of time,

all things store carbon for differing lengths,

our bodies are a type of temporary CO2 containers

Carbon Sinks – places where co2 is stored for either a temporary or indefinite period of time,

Plants, algae and forests store CO2 through photosynthesis

Oceans store CO2 through absorbtion

The soil, grasslands and deserts are also important carbon sinks

Oceans are by far the greatest absorbers of atmospheric CO2

They accomplish this through the exchange of warm and cold water

As warm surface water travels from the equators to the poles it cools and sinks to deeper depths, this deep cold water then circulates back to the equators and rises as it warms

CO2 is absorbed by the cold descending water and is held there or deposited on the ocean floor

Some of the CO2 remains desolved in the seawater and is then released again into the atmosphere as it warms at lower latitudes

Forests and plants are important carbon sinks though they operate on the biological time scale.

In trees the differential rate of carbon absorbtion through photosynthesis to carbon release through respiration changes over lifetime of tree, at first a majority of carbon is retained as it is fixed to generate growth of tree, as growth slows down and tree begins to loose branches and roots it returns more carbon through decompostion, eventually after tree falls it becomes a net carbon emittor.

Forest fires release all carbon stored in tree, good when naturally occurring because makes way for new forest growth that will take up greater amount on co2, bad when clearing for agriculture because no new forest is allowed to grow and ranching use is huge carbon emmitter

This is why rainforest loss is so critical to CC

Eastern US forest regeneration as carbon sink

Missing carbon mystery, the amount of carbon emitted over past century is far greater than scientists have been able to find, where is it? Ocean? Oak tree roots? Deserts?

This is important because systems can become saturated thereby greatly increasing carbon level in atmosphere

In fact recent studies have indicated that the oceans are absorbing carbon at a slower rate causing some scientists to speculate they they may be reaching their capacity

Anthropogenic carbon – the carbon released into the atmosphere through the activities of Man

We are a force of nature

We are adding 80 billion tons of CO2 per year into the atmosphere and this level is rising

This is the use of the suns fossilized energy in the form of coal oil and gas to provide power for industry, transportation, heating and light.

What has occurred is that we have entered into both the biological and geological carbon cycles and have brought about a massive shift in the distribution and storing of carbon. The carbon in the geological cycle that would otherwise be stored underground for millions of years is prematurely released into the atmosphere by our mining and burning of fossil fuels.

Likewise the carbon in the biological cycle that is stored in trees and soil has been massively released through deforestation and agriculture.

Our task, as the UN Framework Convention on Climate Change has worded it is to stabilize greenhouse gas emissions ”at a level that would prevent dangerous anthropogenic interference with the climate system”

Or how to find balance, equilibrium, an equity with our planet.

Some sources: