Carbon Cycle - Atmospheric Flashcards
Why is carbon important?
The dry matter of all living tissue is composed primarily of carbon ( biomass)
Almost all the carbon that gets into the living tissue is from the atmosphere. Plants that we consume turns sunlight into carbohydrates and we consume the carbohydrates ( primary producers)
The concentration of carbon in the atmosphere and the fluxes of carbon through the atmosphere have been closely involved with the development of life on Earth
Concentration of carbon affects climate and affects evolution of life - linked to processes that affect how co2 is absorbed
What do cycles involve?
Pools and fluxes
What is a pool?
A pool ( reservoir) holds a quantity of the chemical in an identifiable form e.g rock, fossil fuel, or dissolved in oceans
Units are usually mass ( often Gt = giga tonne = billion tonnes)
What if a flux?
A flux moves the material from one pool to another at a certain rate ( Gt/year)
What’s the atmospheric co2 atm
406*
Increasing at 1.5 ppm per year and accelerating
280 before industrial rev
330 in 1960s
Talk about the history of atmospheric co2
Carbon dioxide originally emitted by volcanic activity during the formation of earth
Originally no plants to consume co2 ( 500 million years ago) and plants can’t drive weathering so atmospheric co2 continually builds up in earths atmosphere
Peak concentration of co2 probably 3% ( 30,000 ppm)
What is the total amount of carbon on and in Earth?
1 x 10^9 Gt
1 Gt = 1000 Mt
Almost all this carbon ( > 80 percent) is stored in sedimentary rocks
Also like coal, fossil fuels etc
Talk about the long term carbon cycle
Rainwater contains CO2 from the atmosphere. Soil water contains CO2 from respiration and microbial activity.
Hence formation of weak carbonic acid, H2CO3
H2O + CO2 -> H+ + HCO3- H2CO3
Equation uses the co2 and strips it out of the atmosphere and takes it through weathering
Igneous silicate rocks contain minerals such as feldspar which are rich in sodium, potassium, magnesium and calcium
The carbonic acid dissolves the silicate and the dominant ions in the runoff included HCO3-,A’s well as Mg2+, Ca2+, K+ and Na+
The carbon in the runoff flows into the oceans and forms sedimentary magnesium and calcium carbonate rocks
The carbonate rocks are subducted and CO2 is released from volcanoes and hydrothermal vents
Atmospheric CO2 would be used up in about 1 million years by rock weathering if not replenished like this
What are short term pools in the carbon cycle?
Active pools of carbon near Earth’s surface make up 40 000 Gt (0.04 percent of the total)
Examples include soil organic matter, fossil fuels, vegetation, atmospheric C, ocean C
The main exchanges are photosynthesis and respiration ( Net Primary Productivity (NPP), or the production of plant biomass, is equal to all of the carbon taken up by the vegetation through photosynthesis (called Gross Primary Production or GPP) minus the carbon that is lost to respiration.
Combustion - imbalance accelerating long term carbon cycle which affects short term carbon cycle
Volcanic emissions, forest fires and fossil fuel combustion
What are other carbon molecules in the atmosphere?
Methane - CH4 ( decomposition of vegetation - at present at about 1.8 ppm
Carbon monoxide
Background concentration 0.1 ppm
Toxic urban pollutant important trace gas for atmospheric chemistry
Hydrocarbons
Fuels ( coal, oil, petrols, diesel) - unburnt hydrocarbons?
Vegetation ( smoky mountains)
Chlorofluorocarbons -
What is the Greenhouse warming potential?
An index, based upon radiative properties of well-mixed greenhouse
Global warming potential is a measure of how much heat a greenhouse gas traps in the atmosphere up to a specific time horizon, relative to carbon dioxide.
How good at absorbing outgoing thermal infrared radiation
The Kyoto protocol is based on GWP over a 100 year timeframe
Is Methane a highly potent greenhouse gas?
GWP 30 - this means in 1 unit of methane when emitted to atmosphere has the GWP of 30 units of carbon dioxide
When and what was was the paleocene Eocene Thermal maximum? what was the heat produced by?
About 55 million years ago
May be called initial Eocene thermal maximum ( LETM)
And Late Paleocene thermal maximum ( LPTM)
Rapid and transient warning event that lasted ~100- 200 thousand years
Looking at the isotope records people have estimated it shows a 6-8 degree warming
Particular acute warming at high latitudes
They used this as a model event to study
human induced global climate change
Eruption of vast amounts of methane from the ocean into the atmosphere. Huge amounts of methane driving up global warming
How did plants react to surge of warming during the PETM ( paratropical floral response)? How do paratropical plants tend to be pollinated?
Loss in 20 percent of sporomorph taxa could represent a diversity decline ~ 40 percent
They are underrepresented in the fossil record
Paratropical plants tend to be animal pollinated
Produce smaller amounts of pollen which is larger than that of wind pollinated plants
