Earth is more than one Planet · Arney et al (2016, 2017, 2018) Izon et al. (2015, 2017) Climate:...

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Earth is more than one Planet:Lessons from Earth history

Giada ArneyNASA Goddard Space Flight Center

Image by Maggie Turnbull

vegetation

carbon dioxide

methane

oxygen and ozone water

optical nearinfrared

wavelength

NASA EPIC/DSCOVR

Earth is more than one planet

6(now)

A couple examples…

7(now)

PhanerozoicPrecambrian

EonsEarth’s history

Hadean Archean Proterozoic

history of oxygen

Reinhard et al. (2017)

O2 virtually absent (e.g. Farquhar et al. 2001)

no O2 but…

likelyabundant CH4

(e.g. Ueno et al. 2006; Kharecha et al. 2005)

methanogenesiscarbon dioxide + dihydrogen → methane + water CO2 + 4 H2 CH4 + 2 H2O 13

http://metanogen.biotech.uni.wroc.pl/

serpentinizationOlivine + water + carbonic acid → serpentine + magnetite + methane(Fe,Mg)2SiO4 + n·H2O + CO2 → Mg3Si2O5(OH)4 + Fe3O4 + CH4 14

http://www.whoi.edu/

I have abundant methane

methane produced serpentinization

(non-life)

High CH4 production rates life?

(Krissansen-Totton et al 2018)

Abundant CH4, but low

production rate

Less CH4, but high production rate

I have a haze!

late Archean intermittent

hazy periods?e.g. Trainer et al. (2006)Haqq-Misra et al. (2008)

Domagal-Goldman et al. (2008)Wolf & Toon (2010)Zerkle et al. (2012)

Arney et al (2016, 2017, 2018)Izon et al. (2015, 2017)

Climate:Haze cools surface by 20-30 K

Habitability can be maintained in the presence of other greenhouse gases (e.g. 2% CO2)

UV shielding:Haze is a good

UV shield

blocks 97% of UVC radiation

reflection spectra

thin haze

thick haze

Haze extinction

H2O H2O

H2OCH4

Earth with pCO2 = 0.018 bar, 1 bar total pressure

Arney et al. (2016)

history of oxygen

Reinhard et al. (2017)

O2 level possibly as low as 0.1% of the present day level (Planavsky et al. 2014)

low O2 but…

likely still able to detect ozone

e.g. Reinhard et al. (2017), Olson et al. (2018), Schwieterman et al. (2019)

25Olson et al. 2018

biological seasonal ozone variations

Olson et al 2018

Earth is more than one Planet · Arney et al (2016, 2017, 2018) Izon et al. (2015, 2017) Climate:...

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