ON THE CHALLENGES OF SIMULATING THE
EARLY MARS ENVIRONMENT(S) WITH
CLIMATE MODELS AND LAB EXPERIMENTS
Martin Turbet, Jean-Michel Hartmann, Ha Tran, ChristianBoulet, Tijs Karman, Didier Mondelain, Alain Campargue,
François Forget, Ehouarn Millour, Edwin Kite, Olivier Pirali,
Cédric Gillmann, Baptiste Baudin, Vladimir Svetsov

THE EARLY MARS ENIGMA

Huygens Crater20 km

MAP OF KNOWN VALLEY NETWORKSHynek et al. 2010

Ø Formed 3.5-3.8 billion years ago
Ø Likely required > 105 years to form

OVERWHELMING NUMBER OF PIECES OF EVIDENCEFOR THE PRESENCE OF LIQUID WATER
1) Valley Networks

4

OVERWHELMING NUMBER OF PIECES OF EVIDENCEFOR THE PRESENCE OF LIQUID WATER
1) Valley Networks
2) High erosion rates

5Crater infilling + rim erosion

HIGH EROSION RATES OFOLD CRATERS (3.5-4Gyo)
Craddock & Howard 2002
Mangold et al. 2012

OVERWHELMING NUMBER OF PIECES OF EVIDENCEFOR THE PRESENCE OF LIQUID WATER
1) Valley Networks
2) High erosion rates
3) Presence of sediments

7

Malin and Edget 2003
Moore et al. 2003
See also
Mangold and Ansan 2006

Curiosity, Gale Crater, 07/2014

OVERWHELMING NUMBER OF PIECES OF EVIDENCEFOR THE PRESENCE OF LIQUID WATER
1) Valley Networks
2) High erosion rates
3) Presence of sediments
4) Widespread hydrated minerals

10MAP OF HYDROUS MINERAL DETECTIONS
Carter et al. 2011
See most recent map in Carter et al. 2019, 2020

OVERWHELMING NUMBER OF PIECES OF EVIDENCEFOR THE PRESENCE OF LIQUID WATER
1) Valley Networks
2) High erosion rates
3) Presence of sediments
4) Widespread hydrated minerals5) Shorelines*, evidence for tsunami events*
12*controversial

Artist's depiction of the life cycle of a Sun-like star
Credit: ESO

THE FAINT YOUNG SUN:Ø The Sun was about 25% fainter 3.5-4 billion years ago
Ø Mars received about 0.32 solar constant13

WHAT ATMOSPHERE FOR EARLY MARS?

See review in Kite (2019)CAN A PURE CO2 ATMOSPHERE WARM EARLY MARS?

CAN A PURE CO2 ATMOSPHERE WARM EARLY MARS?

Also
Kasting, 1991
Forget and Pierrehumbert, 1997
Haberle, 1998
Mischna et al, 2000

CAN A PURE CO2 ATMOSPHERE WARM EARLY MARS?

Also
Kasting, 1991
Forget and Pierrehumbert, 1997
Haberle, 1998
Mischna et al, 2000

CAN A PURE CO2 ATMOSPHERE WARM EARLY MARS?

Also
Kasting, 1991
Forget and Pierrehumbert, 1997
Haberle, 1998
Mischna et al, 2000

CAN A PURE CO2 ATMOSPHERE WARM EARLY MARS?

Also
Kasting, 1991
Forget and Pierrehumbert, 1997
Haberle, 1998
Mischna et al, 2000

CAN A PURE CO2 ATMOSPHERE WARM EARLY MARS?

Also
Kasting, 1991
Forget and Pierrehumbert, 1997
Haberle, 1998
Mischna et al, 2000

THE EARLY MARSENIGMA

Ps=0.5 bar

Temperature (K)Early Mars with
CO2/N2/H2O should be cold
Ps = 2 bar

Temperature (K)CO2 atmosphere:
Annual mean surface temperature

For a review, see:Wordsworth 2016, AREPS
Haberle et al. 2017, Cambridge Univ. Press

Obliquity = 25°[ CCN] = 105 kg-1

Forget et al. 2013

SCENARIOS FOR THE WARMING OF EARLY MARSGREENHOUSE EFFECT OF CLOUDS

Follow the debate

CO2 ice
CO2 icecloudsForget & Pierrehumbert 1997
Forget et al. 2013
Kitzmann et al. 2013, 2016, 2017

H2O icecloudsUrata & Toon 2013
Wordsworth et al. 2013
Ramirez & Kasting 2017
Turbet et al. 2020a

H2O iceWARMING BY CO2 ICE CLOUDS BACK-SCATTERING
Forget & Pierrehumbert 1997

28

WARMING BY CO2 ICE CLOUDS BACK-SCATTERING
CO2 ice clouds coverage

Forget et al. 2013

Main caveats:
1) Partial CO2 cloud coverage (Forget et al. 2013)
2) Scattering effect overestimated (Kitzmann 2016)
29

WARMING BY H2O ICE CLOUDSUrata & Toon 2013
Wordsworth et al. 2013
Ramirez & Kasting 2017
Turbet et al. 2020a

Main caveats:
1) Cloud coverage must be very high2) Size of H2O ice particles must be tuned3) Altitude of clouds must be tuned
4) Precipitations must be artificially suppressed

Ramirez & Kasting 2017Turbet et al. 2020
30

SCENARIOS FOR THE WARMING OF EARLY MARSVOLCANISM
Follow the debate
Johnson et al. 2008
Tian et al. 2010
Mischna et al. 2013
Halevy & Head 2014
Kerber et al. 2015

WARMING BY VOLCANIC GASES (SO2, H2S)

Freezing point of water32

Kerber et al. 2015

WARMING BY VOLCANIC GASES (SO2, H2S)
Main caveat:
Cooling effect of aerosols
Freezing point of water

33

Kerber et al. 2015

SCENARIOS FOR THE WARMING OF EARLY MARS

Follow the debate
Segura et al. 2002, 2008, 2012
Turbet 2018
Steakley et al. 2019
Turbet et al. 2020aIMPACTSIMPACT CRATERS ON MARSMap of impact craters on Mars

Made with the Robbins crater databaseMap of impact craters on Mars

Made with the Robbins crater databaseMap of impact craters on Mars

ArgyreHellas

Made with the Robbins crater database

VERY BIG IMPACT EVENTS
Surface temperatures (K)Turbet et al. 2020a

100km diameter meteorite
impacting a 1bar CO2 atmosphereØ Atmosphere + Subsurface = 500 Kelvins
Ø Vaporization of 1bar of H2O (30m GEL)

Rainfall rates (mm/day)

39

Cloud coverage

VERY BIG IMPACT EVENTS
Surface temperatures (K)Turbet et al. 2020a

100km diameter meteorite
impacting a 1bar CO2 atmosphereØ Atmosphere + Subsurface = 500 Kelvins
Ø Vaporization of 1bar of H2O (30m GEL)

Rainfall rates (mm/day)40

Cloud coverage

VERY LARGE IMPACT EVENTS
Turbet et al. 2020a

Cumulated rainfall in
3D climate simulation

VERY LARGE IMPACT EVENTS
Turbet et al. 2020a

Cumulated rainfall in
3D climate simulation

Positions of valley
networks

LARGE IMPACTS WITH A 1-D CLOUD-FREE CLIMATE MODEL
Turbet et al. 2020a

H2O partial pressure (bar)1010.110-310-50.1

1

CO2 partial pressure (bar)10

LARGE IMPACTS WITH A 1-D CLOUD-FREE CLIMATE MODEL
Turbet et al. 2020a

H2O partial pressure (bar)1010.1OUT OF
EQUILIRIUM

10-310-50.1

1

CO2 partial pressure (bar)10

LARGE IMPACTS WITH A 1-D CLOUD-FREE CLIMATE MODEL
Turbet et al. 2020a

H2O partial pressure (bar)1010.1

10-3

10-50.1

1

CO2 partial pressure (bar)10

LARGE IMPACTS WITH A 1-D CLOUD-FREE CLIMATE MODEL
Turbet et al. 2020a

H2O partial pressure (bar)1010.110-30°C

10-50.1

1

CO2 partial pressure (bar)10

LARGE IMPACTS WITH A 1-D
CLOUDY CLIMATE MODEL
Tsurface= 273K

Tsurface= 323K

Tsurface= 373K
Turbet et al. 2020

0%50%
Cloud coverage (in %)100%50VERY LARGE IMPACTS
In summary,Turbet et al. 2020a

Ø No self-sustained ‘RUNAWAY CLIMATE’Ø Warming is instead SHORT-LIVED( O(101) martian years for the largest impact events).

Ø Precipitation are (1) deluge-style, (2) insufficientand (3) uncorrelated with valley networks positions.

Remark: Very large impacts could have contributed to (1)mineralogy and (2) the crater rim degradation.
54

Map of impact craters on Mars

ArgyreHellas

Made with the Robbins crater databaseMap of impact craters on Mars

Made with the Robbins crater database

HYDROCODE SIMULATIONS
Turbet 2018, PhD thesis

15-km diameter body hitting the surface of MarsdensityHYDROCODESIMULATIONSEjecta field after theimpact event

Turbet 2018, PhD thesis

64

RESULTS OF 3-D GLOBAL CLIMATE MODELINITIAL STATE
1bar CO2
atmosphere
Stabilizedsurface
ice reservoirs

Turbet 2018, PhD thesis

SurfaceTemperatures(K)

Vaporcolumn(kg/m²)
Surfaceicedeposits(mm)
65

RESULTS OF 3-D GLOBAL CLIMATE MODELINITIAL STATE
1bar CO2
atmosphere
Stabilized
surface
ice reservoirs

Turbet 2018, PhD thesis

SurfaceTemperatures(K)

Vaporcolumn(kg/m²)
Surfaceicedeposits(mm)66

RESULTS OF 3-D GLOBAL CLIMATE MODEL
Upper atmosphere water ice clouds sediment rapidly
water vapour

Altitude(km)Altitude(km)water ice clouds

Longitude

Longitude
Turbet 2018, PhD thesis

67

RESULTS OF 3-D GLOBAL CLIMATE MODEL
Upper atmosphere water ice clouds sediment rapidly
water vapour

Altitude(km)Altitude(km)water ice clouds

Longitude

Longitude
Turbet 2018, PhD thesis

68Turbet 2018, PhD thesis

69

MELTING OF THE PERMANENT ICE RESERVOIRSØ Results:
Melting of a 85 cm Global
Equivalent Layer MAXIMUM

Turbet 2018, PhD thesis70

AMOUNT OF ICE MELTING
Ø Maximum cumulated melt production:•••

Turbet 2018, PhD thesis

150m GEL for 5-50km diameter impactors
70m GEL for <5 km diameter impactors
220m GEL in total

Ø Minimum total water required to carve the valley networks:••

5000m GEL (Luo et al. 2017)
640m GEL (Rosenberg et al. 2018)
CONCLUSION:MELT PRODUCTION IS NOT SUFFICIENT ENOUGHTO CARVE THE VALLEY NETWORKS71

REDUCING GASES (H2)A viable alternative to warm early Mars?
Possible sources of H2:• Outgassing from a reduced early Martian mantle (Ramirez et al. 2014)• Serpentinization (see Chassefière et al. 2016)• Radiolysis (Tarnas et al. 2018)• Atmospheric thermochemistry following large meteorite impacts (Haberle et al. 2019)

REDUCING GASES (H2)A viable alternative to warm early Mars?
Surface Temperature (K)1D calculations, 2bar CO2 atmosphere

0°C

Ramirez et al. 2014

Hydrogen content (%)

73

REDUCING GASES (H2)A viable alternative to warm early Mars?
Surface Temperature (K)1D calculations, 2bar CO2 atmosphere

0°C
Wordsworth et al. 2017
Ramirez et al. 2014

Hydrogen content (%)

74

COLLISION-INDUCEDABSORPTIONS
N2-H2 (exp+theory)
CO2-H2 (theory)

Wordsworth et al. 2017

Ramirez et al. 2014

EXPERIMENTS AT THE SOLEIL SYNCHROTRON / AILES LINES
Turbet et al. 2019,Icarus

76

COLLISION-INDUCEDABSORPTIONS
N2-H2 (exp+theory)
CO2-H2 (theory)

Wordsworth et al. 2017

Ramirez et al. 2014

Turbet et al. 2019, Icarus

COLLISION-INDUCEDABSORPTIONS
N2-H2 (exp+theory)
CO2-H2 (theory)

Wordsworth et al. 2017

CO2-H2 (exp)Ramirez et al. 2014

Turbet et al. 2019, Icarus

COLLISION-INDUCEDABSORPTIONS
N2-H2 (exp+theory)
CO2-H2 (theory)

Wordsworth et al. 2017

CO2-H2 (exp)
CO2-H2 (2nd exp)
Ramirez et al. 2014

Turbet et al. 2019, Icarus
Turbet et al. 2020b (available on arXiv)

CO2+H2 COLLISION-INDUCED ABSORPTIONS(1) EXPERIMENTS

Turbet et al. 2019,
IcarusTurbet et al. 2020,
sub. to Icarus(see arXiv)
2nd experiment

1st experiment86

CO2+H2 COLLISION-INDUCED ABSORPTIONS(2) CALCULS

Turbet et al. 2020,
sub. to Icarus(see arXiv)

calculations (300K)

2nd experiment

1st experiment87

CO2+H2 COLLISION-INDUCED ABSORPTIONS(2) CALCULS

Turbet et al. 2020,
sub. to Icarus(see arXiv)
2nd experiment
1st experimentcalculations (300K)

88

CO2+H2 COLLISION-INDUCED ABSORPTIONS(2) CALCULS

500K

Turbet et al. 2020,
sub. to Icarus(see arXiv)

2nd experiment
1st experiment100K
calculations (300K)
89

REDUCING GASES (H2)A viable alternative to warm early Mars?
Surface Temperature (K)1D calculations, 2bar CO2 atmosphere

0°C

Wordsworth
et al. 2017

Ramirez et al. 2014

Hydrogen content (%)

94

REDUCING GASES (H2)A viable alternative to warm early Mars?
Surface Temperature (K)1D calculations, 2bar CO2 atmosphere

0°C

Wordsworth
et al. 2017
Exp-fitted CIA

Turbet et al. 2020b(available on arXiv)

Ramirez et al. 2014

Hydrogen content (%)

95

CO2+H2 COLLISION-INDUCED ABSORPTIONS(2) CALCULS

500K

Turbet et al. 2020,
sub. to Icarus(see arXiv)

2nd experiment
1st experiment100K
calculations (300K)
96

THE CAVITY RING DOWN SPECTROSCOPY (CRDS)
GRENOBLE EXPERIMENTAL SETUP

Threshold
Laser ON

Laser OFF

Frequency scan
COMPLEAT Project – Credit: D. Mondelain and A. Campargue

Simulation of the Early Mars Climate : a hierarchy of models…

Ø 1D global radiative convective models_ To evaluate global mean surface temperature with various atmospheres(e.g. Kasting et al. 1991, Forget and Pollack 1997, Wordsworth et al. 2010, Ramirez et al.
2014, 2017, Turbet & Tran 2017)

Simulation of the Early Mars Climate : a hierarchy of models…

Ø 1D global radiative convective models_ To evaluate global mean surface temperature with various atmospheres(e.g. Kasting et al. 1991, Forget and Pollack 1997, Wordsworth et al. 2010, Ramirez et al.
2014, 2017, Turbet & Tran 2017, Turbet et al. 2020ab)Ø 3D Global Climate model with a converged watercycle_ To evaluate local surface temperatures & their variations with season,obliquity, the role of clouds, etc …
(e.g. Forget et al. 2013, Mischna et al. 2013, Kerber et al. 2015, Turbet & Forget 2019)_ To evaluate rain, snow melting, and long-term evolution of the full watercycle.
(e.g. Wordsworth et al. 2013, 2015, Turbet et al. 2017a, see also Turbet’s 2018 PhD thesis,Turbet et al. 2020a)

3-D CLIMATE SIMULATIONS OF
REDUCING ATMOSPHERES ON MARS
Turbet & Forget, in preparation

1) Implementation of the radiative
effect of CO2+H2 atmospheres

3-D CLIMATE SIMULATIONS OFREDUCING ATMOSPHERES ON MARS
Turbet & Forget, in preparation

1) Implementation of the radiative
effect of CO2+H2 atmospheres
2) Implementation of water reservoirs
and their effect on topography

3-D CLIMATE SIMULATIONS OF
REDUCING ATMOSPHERES ON MARS
Turbet & Forget, in preparation

1) Implementation of the radiative
effect of CO2+H2 atmospheres
2) Implementation of water reservoirs
and their effect on topography3) Implementation of the climatic effect ofimpact crater lakes and their evolution

VO = VI+(AT-AL)P RB+ALP-EAL
Matsubara et al. 2011

3D CLIMATE
MODELINGSurfaceTemperature(K)

0.8barpure CO2
Atmosphere

Permanent
ice deposits(mm)

Liquid waterfrom seasonalmelting (m)Turbet & Forget, in preparation

3D CLIMATE MODELING

SurfaceTemperature(K)

1st result –Average Tsurf > 273K condition
doesn’t hold in 3D••

Water trapped in cold points
Ice/Snow albedo feedback

Permanent
ice deposits(mm)

Example: 0.8bar CO2
atmospherewith 20% H2, low watercontent

Liquid waterfrom seasonalmelting (m)Turbet & Forget, in preparation

104

3D CLIMATE MODELING
2nd result –The temperature of the coldest
point of the planet (usually thehighlands for thick atmospheres)needs to be above 273K to avoid
water cold trapping.

SurfaceTemperature(K)

Permanentice deposits(mm)à Need more H2 to ‘warm’ early Mars

Example: 2.3bar CO2
atmosphere with 5% H2, lowwater content

Liquid waterfrom seasonalmelting (m)Turbet & Forget, in preparation

105

3D CLIMATE MODELING
3rd result« Icy highland » scenario canalso work in warm mode (« WetHighlands) with water trappedin the liquid form in thesouthern highland lakes
Example: 2.3bar CO2
atmosphere with 5% H2, lowwater content(~1m GEL)
Turbet & Forget, in preparation

Cumulated
runoff (m/year)

Lake coverage(in %)

Valley networks
positions(pre-TPW)
106

3D CLIMATE MODELING
4th result –Position of impact-crater lakes
and precipitation/runoff can betuned assuming various water
reservoir size and position
Example: 2.3bar CO2
atmosphere with 5% H2, lowwater content(~10m GEL)
Turbet & Forget, in preparation

Cumulated
runoff (m/year)

Lake coverage(in %)

Valley networks
positions(pre-TPW)
107

3D CLIMATE MODELING
Cumulated
runoff (m/year)

2.3bar CO2
atmospherewith 5% H2
with small
oceansLake coverage(in %)

Valley networks
positionsTurbet & Forget, in preparation

108

3D CLIMATE MODELING
Cumulatedrunoff (m/year)

2.3bar CO2
atmospherewith 5% H2
with large
oceansLake coverage(in %)

Valley networks
positionsTurbet & Forget, in preparation

109

CONCLUSIONS/SUMMARY•

The « Hydrogen solution » is promising but still challenging:– The measured Collision-Induced Absorption (inducing greenhouse effect) not as strongas previously estimated– In 3D more greenhouse effect is required to avoid complete freezing of the water in cold
traps (especially if one want to avoid any glaciation !)•••However, with enough greenhouse effect promising solution with realistic
run-off seems possible.
Too much greenhouse effect or too much water can provide irrealistic
results (for instance with too many open-lake basin, or heavy precipitationnear coastlines).
To be continued !
110