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hi i am sir watanabe from the university

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of tokyo i talk about the competition

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between concentra and syria with ring on

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detecting the extraterrestrial life is

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one of the ultimate goal of the

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observations of exoplanets

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upcoming observations of exoplanetary

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atmosphere would allow us to detect

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design of life in the future so that the

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process controlling the composition of

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the planetary atmosphere is now actively

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discussed

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among the constitute of the primary

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atmosphere oxygen has been discussed to

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be one of the strong biosignatures if

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you detected on x granite

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in the present atmosphere of the earth

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oxygen compresses 12 percent

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because oxygen is produced by oxygenic

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photosynthesis high concentration of

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oxygen in the exoplanetary atmosphere

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may indicate the existence of life

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thus how the oxygen level is controlled

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in the primary atmosphere is crucial to

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interpret the biosignature

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for this purpose we focus on the

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evolution of the oxygen level on earth

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in the history of the earth the

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atmospheric oxygen level was not kept as

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high as it is today in the early years

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the oxygen level was smaller than

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represented by more

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order of magnitude

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from such an anoxic condition

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the atmospheric oxygen level abruptly

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increased at around 2.3 billion years

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ago which is known as the great

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oxidation event

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various mechanisms has been proposed to

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explain degradation of great oxidation

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event but here i focus on the mechanism

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in the presentation the production rate

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of oxygen is limited by the supply of

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nutrient on a global perspective the

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marine primary productivity is limited

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by the rivalry input of phosphorus thus

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the atmospheric oxygen level is strongly

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linked to the phosphorus cycle on the

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planetary surface phosphorus is produced

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during the weathering of the carbonate

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and silicate mineral on the continent

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that grassed and is

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removed from the ocean as an organic

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carbon or inorganic compounds

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weathering of seafloor basalt is not

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expected to provide phosphorus because

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it precipitates as an appetite in dc

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flow so the phosphorus input rate and

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the atmospheric oxygen level depends on

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the concentration efficiency

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so the red shaded area in the right

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figure

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is the marine primary productivity

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estimated based on the phosphorus budget

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which is increased during the middle to

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let again

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this increase is driven by the growth of

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the congenital crust which is estimated

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to have happened during this period

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thus the growth of the congenital crust

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would becomes crucial

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in controlling the atmospheric

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composition through

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the biogeochemical processes associated

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with the phosphorus cycle

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however the consequence of the

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congenital growth on the atmospheric

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composition has not been systematically

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and one of the other important aspect of

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the earth red planets is the variation

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of orbital parameters

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these are the calculated variations of

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oberquity and the planetary

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orbital eccentricity of the past earth

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and mass

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it is well known that this kind of

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orbital variation have caused the

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glacial cyclone quaternary earth even

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though the change in the orbital

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parameters on earth especially obligated

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is small because of the existence of the

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moon

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in a product context of the exoplanet

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the various of orbital parameters could

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vary in a wider range of the parameter

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space

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it has been discussed that the different

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values of obligation and eccentricity

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could affect the climate and

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habitability of earth-like planets

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however how the different varies of

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orbital parameters could affect the

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coupled system of climate biosphere and

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atoms has not been systematically

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demonstrated

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so

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our purpose here is to elucidate the

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links between the growth of the

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continental crust orbital parameters and

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the atmospheric composition to discuss

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the country and condition to achieve the

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high atmospheric oxygen level in the

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atmosphere of the earth and earth-like

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planets with phosphorus limited marine

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for this purpose we employed a

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simplified ocean and atmosphere box

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model in which a long-time steady state

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of phosphorus carbon and oxygen cycle is

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calculated

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we use the parameterization of

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atmospheric photochemistry to calculate

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the budget of oxygen in the atmosphere

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for the climate model we use the

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parameterization based on

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one-dimensional radiative convective

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models

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and we also use the meridian

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one-dimensional energy balanced climate

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model to illustrate the rows of orbital

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parameters

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the steady-state co2 level is buffered

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by the container and zero weathering

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whose relative contribution becomes

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crucial on the

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so first we show the dependencies of the

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concentrated weathering and seafloor

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measuring on co2 and temperature which

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becomes crucial in controlling the

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rivalry phosphorus input rate

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in this figure the sensitivity of

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continent and separating to the

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atmospheric sealed level and temperature

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is shown the container weathering has a

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stronger co2 dependency while seafloor

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weathering has a much stronger

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as a result combining these dependencies

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sephora weathering rate has a stronger

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sensitivity to the climate warming

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caused by the change in atmospheric co2

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level while the content arrest and grade

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also increases with co2 driven warming

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as a result the riverline phosphorus

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input rate is also increased because

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container weathering is enhanced with

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because not only is it content that are

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weathering but also that seafaring

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buffers decline it the phosphorus input

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rate depends on the climate change as

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so next we should discuss the

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sensitivity to the machine driven

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warming

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in this figure the response of the

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phosphorous supply rate to the

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atmospheric missing level is summarized

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different lines represent the result

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with different pseudo outgassing flux

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because methane is a strong greenhouse

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gas it increases the equilibrium surface

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temperature

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where it decreases the equilibrium

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atmospheric co2 level through a silicate

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weathering negative feedback

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because lower sealed

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atmosphere to level and higher surface

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temperature promotes the severe

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weathering strongly

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the increase in the atmospheric messing

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level due to the decrease in the

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continental weathering as showing the

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solid line

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hence the river and phosphorus supply

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rate is also decreased

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thus the competition between continental

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and seafloor weighting could affect the

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then what happens

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if content area is increased as a result

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of the container growth

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these are the response of the co2

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phosphorous input rate and oxygen level

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against the increasing contenter area

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different lines represent a different

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co2 addressing rate

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as the container area increases steady

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state co2 level is decreased

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as a result of

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increasing

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congenital weight and efficiency

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the primary productivity in the ocean

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increases as a result of an increased

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phosphorus input

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to the ocean

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so now we see the atmospheric oxygen

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level

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when the content area is very small

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there's only an equilibrium

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with small atmospheric oxygen level even

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with large shield glassing rate

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with the present theory guessing rate

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shown in blue line the atmospheric

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oxygen level slightly increases but it

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is still kept low even with the present

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content area on the other hand when the

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co2 gassing rate is sufficient the

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branch of low oxygen level disappears

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as the content area increases as the

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gradient

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and the abrupt rise of oxygen is

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triggered

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so contented growth can drive the abrupt

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increase in the atmospheric oxygen when

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next we see the dependency of a model on

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orbital parameters

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this is a response of the co2 and global

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neon mean temperature

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and surface temperature and the

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weathering rates to different varieties

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of mean eccentricity of a planet

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the atmospheric co2 level decreases and

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the surface temperature increases

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against the

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increasing eccentricity

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in this case the solar irradiance at low

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ratio regions

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increases with the increasing

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eccentricity so that the global mean

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surface temperature also increases

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because container weathering is less

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effective under low co2 and high

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temperature conditions there phosphorus

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input and the marine primary

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productivity as small

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on the other hand this is the response

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of the different mean obligation of a

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planet

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the atmospheric field level is peaked at

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around 40 to 50

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degrees of obligation so that the

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weathering rate is also dependent on

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operating

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this is associated with the rational

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distribution of the insulation forcing

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it is uniformly distributed at around

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this values of obligation which

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resulted in the low global temperature

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thus both obligated and eccentricity

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could affect the marine biosphere and

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atmosphere

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through the competition of the

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so here we summarize the response of the

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co2 primary productivity and the

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atmospheric oxygen level to the

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different varies of obligation and

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eccentricity

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as we showed the atmospheric co2 level

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and the primary productivity is high

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under the condition with low

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eccentricity and also dependent on

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obliquity

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as a result the range

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of the condition that can sustain the

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high atmospheric oxygen level could vary

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as in the case we are showing here

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thus orbital parameters are important

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not only for climate and habitability

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but also the atmosphere and marine

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biological chemistry through the

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competition between container and

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seafloor weathering

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so this is the summary of our

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presentation the marine biosphere and

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atmospheric composition could be

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affected by the co2 and missing driven

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warmings

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and also by contented growth and also by

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the

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different

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values of

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orbital parameters through the

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competition between congenital and

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severe weathering

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which is a fundamental process for the