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[Music]

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[Applause]

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yes thank you very much and good morning

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everyone my name is he asked to attend a

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BA from the University of Tokyo in Japan

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and I'm PhD student in university of

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tokyo and we are working with these

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people and so today I'd like to talk

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about the global carbon cycle in the

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areas so in the areas especially in the

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Archaean D from 4 billion years ago to

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the 2.5 years ago the solar luminosity

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was just around 80% relativity present

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on the other hand this figure shows the

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reconstructed sea water temperature and

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which suggests that in the area in the

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areas the surface temperature was warmer

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warm or even hot environment exceeding

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50 degrees so to achieve such warm our

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Eve hot environment under the dimension

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and greenhouse gases are considered to

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be necessary so the most Green has a

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most possible greenhouse gases carbon

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dioxide but the warm sea is too warm to

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pass the warmest parts of surface

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temperature much warmer at the present

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Emma co2 only co2 is not only co2 only

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with co2 also yeah only always and to

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achieve such warm environment only with

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co2 it's difficult in a range of a

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reconstructed path see what a

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temperature so and another greenhouse

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gas that is considered to be compensated

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see the insufficient green greenhouse

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warming is missing missing is produced

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by similar machines in the early ocean

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and in the area and it's produced by the

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microbiology in the areas on decomposing

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the organic carbon but missing is a

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highly reactive photochemical reactive

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species so that to achieve high machine

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level in the atmosphere a much amount of

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missing should be produced from the

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ocean so in the early years anoxic or us

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the balance between sealed

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balance between shield to Anzio and

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missing was different from the present

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condition so to consider the climate

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stability in the areas we need to

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consider not only the co2 cycle but also

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the cycle of missing and warming by

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missing so we investigate C crowbar

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carbon budget and carbon cycle under the

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anoxic early Earth system in the area by

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developing a couple model of atmosphere

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photochemistry and marine microbial

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ecosystem and global carbon cycle and

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this is a schematic of the model we

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developed and as you can see we

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characterize the poor chemical processes

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and marine microbial reactions in the

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context of the global carbon cycle so we

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explain it's part of the model briefly

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so called the photochemical plot model

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part we use the Atmos model a

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one-dimensional photochemical model if

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it is identical to the last bit that

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last week I used and so I don't explain

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the detail but using this model we can

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calculate the vertical structure of many

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species and balance between them like

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this so and on this photochemical model

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we further introduce a chemical reaction

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pathway of the marine microbial

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ecosystem and we actually as a lower

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boundary condition and we assume the

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hydrogen based and iron based

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photosynthesis as a primary produces the

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anoxic environment and we also

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considered the Isetta chain which uses

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carbon monoxide as an electron donor so

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and we assumed that the activity is

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limited by the supply of each electron

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donor

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so we also curve and consider the

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activity by heterotrophs that food

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decomposes the organic carbon so as you

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can see this rip in these reactions the

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primary producers constant co2 where

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others produce co2 right so we

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considered such photo chemical and

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microbial reactions in the context of

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the global commerce cycle so in the

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anoxic areas condition the carbon

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dioxide produced by degassing is

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considered to be balanced by the

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consumption by variable organic carbon

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and the native area of English carbon

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that is and continental watering and c4

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weathering and here we introduce the

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balance of the ecosystem reactions and

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photochemical reactions into the

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speranza quick over equation by

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calculating the necessary flux and

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necessary weathering flux to achieve

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this balance of equation we can get C

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equilibrium co2 level and see what a

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team and so fast temperature so we move

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on to the results section and first of

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all we I shows a result without zero

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weathering and and on the last ride I

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chose a relative with c4 always I think

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so this is a result and this figure

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shows is atmospheric co2 missing and

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surface temperature and on different co2

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degassing rating as you can see we see

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simultaneously estimated both the

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atmospheric co2 and missing at the same

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time of the century and as you can see

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on shaded area there is a Mars for

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equilibrium exists why it's hot climate

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mode which has a high co2 emission level

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and the other is cold climate model

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which is an unstable solution unstable

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equilibrium state and so why this low

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co2 condition is unstable to assess this

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to understand this I see the each item

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of the co2 consumption

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processes and so this is a left figure I

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should but the horizontal axis will co2

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degassing but on the bar and only

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quadrivium

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it is balanced by the co2 consumption so

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if we switch the axis the new vertical

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axis corresponds to the co2 consumption

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that is balanced by co2 degassing and if

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we plot different processes of co2

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consumption as you can see on hot

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climate model the consumption by

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continental weathering is dominant which

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is an equilibrium by Walker feedback on

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the other hand on unstable cold climate

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state in the consumption by a coupled

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system of photochemical reactions and

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marine microbial reactions are dominant

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so and associated with consumption on

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these conditions the hydrocarbon haze

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that can be seen in the tyrants

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atmosphere is formed in the atmosphere

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so so then so it is associated with

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consumption so I explained this so first

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of all I explained the photochemical co2

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consumption so this figure shows a net

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co2 consumption in the atmosphere by

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photochemical reactions and as you can

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see on any condition co2 is consumed

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within the atmosphere this large

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consumption flux is actually but

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compensated by the net microbial co2

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production from the ocean especially in

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the hot climate stable solution but

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there is a steering imbalance in the

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Annex anoxic unstable so hazy solution

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so and this imbalance is equals to the

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pre production and removal of

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hydrocarbon erazor in the atmosphere so

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I explain this using our reaction and

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schematic of the reaction pathway so

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first of all I explain the co2

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consumption in the atmosphere and the

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atmosphere co2 is photo dissociated into

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co and co reacts with hydroxyl radical

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in the end of atmosphere to form co2

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alright usually this is balanced but

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under anoxic Archaean condition the

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strong missing flux from the ocean by

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microbiology a consumes consumes the

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hydroxyl radical in the lower atmosphere

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so that this reaction does not proceed

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and that much so that as a result the

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atmospheric reaction works as a net

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photochemical co2 consumption on any

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condition so and this last consumption

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flux is compensated by the reaction by a

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solutions and methanogens

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however I own not hazy condition but

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once he is formed in the atmosphere and

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part of the meeting

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part of the missing is converted to

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hydrocarbon aerosol particles and they

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settle down in the atmosphere and

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finally removed by ring and intestine

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and sinks into the ocean by internal

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waves so as a result and part of the

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dissociated co2 is converted to CO and

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missing and hydrocarbon hazen removed

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from the atmosphere ocean system so that

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remember a formation of his works as a

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co2 formation of his this to see it

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decrease in co2 level so once your two

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lever is decreased the atmosphere gets

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more reducing so that haze formation is

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enhanced and so this feedback mechanism

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works as a positive feedback hole in the

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climate system so making the sister l so

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making this so this makes the system

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unstable regardless of the optical

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properties of the haze particles and as

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a result on low co2 condition she is

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constantly in the cup water system of

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photochemistry and marine microbial

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reactions so that there's a carefully

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characteristic shape like a vari and co2

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consumption and you if you switch the

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axis again hey you get characteristic

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shapes of equilibrium so finally if we

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consider the uncertainty is the

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parameter especially the weathering a

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continental weathering efficiency egg

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equilibrium can be represented like this

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as a result in the anoxic Archaean

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Indian aqua corners the hot climate mode

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and the robbery frozen state is the only

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stable solution and the present climate

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state is under hazy unstable solution so

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and the hot reconstructs and one

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reconstruction by phosphate or even hot

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reconstruction by charts a could be

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achieved on a present co2 degassing co2

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degassing great

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and and if the secret was earning who is

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effectively working as David's exist

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and the surface temperature does not

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exist 40 degrees Celsius but the our

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main conclusion that also but our main

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conclusion that sea anoxic has a

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condition it's unstable is unchanged so

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and this is a summary so my take home

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message is that anoxic has a condition

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in the early Earth is unstable and thank

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you very much sorry I didn't explain

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that in the hurry annex anoxic rot

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reducing atmosphere like that of spider

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the hydric haze that is composed of

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hydrocarbon particles composting they

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are higher altitude of the atmosphere so

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I'm in this one I just have a comment

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which is that earlier this year with

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Kevin's only we published a paper about

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xenon fractionation how that's related

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to hydrogen escape and methane levels

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and one of the kind of conclusions which

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may be a little bit hidden in that paper

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is that for the most part we don't think

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that the early Earth could have been

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hazy because that messes up in it

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affects the xenon isotopes fractionation

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xenon can be taken all into organic haze

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particles so that would support your

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conclusion oh so for most of the time it

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must have been a haze free Atmos mm-hmm

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all right thank you very much

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ah yeah thank you and this alright so so

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if his is not formally the atmosphere

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the co2 consumption by photochemical

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process is is balanced by this pathway

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by a microbiological reactions but if

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haze is formed in the atmosphere the

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parties and so duties and associated in

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Co first and this Co is converted to

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missing to form hydrocarbon haze so that

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part of C and a part of the this pathway

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is depleted because this pathway is

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affected so so after it is removed in

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dissolution ah so yeah that's a very

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good question Matt and edit because this

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is so much reduced hydrocarbon and to

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own present ocean condition and

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basically oxygen is necessary to

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decompose such reduced hydrocarbon so we

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think that so on anoxic condition the

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hydrocarbon haze is difficult to be

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decomposed but and I think that's partly

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its I think it is partly decomposed and

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to some extent and so this is a very

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important point so I will assess about