Cited by 333Space Science and Extraterrestrial LifeAstro and Planetary SciencePlanetary Science and Exploration

The DOI matches its Crossref record; 138 of the 138 references it cites were found in a registry or an index; none of the 147 sources its claims cite is checked for support yet.

The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth

Open access

Arney, Giada, Domagal-Goldman, Shawn D., Meadows, Victoria S., Wolf, Eric T., Schwieterman, Edward, Charnay, Benjamin, Claire, Mark, Hébrard, Eric, Trainer, Melissa G.·2016·Astrobiology

DOI 10.1089/ast.2015.1422PMC PMC5148108

Open this paper in CoChat — free account

Abstract

Recognizing whether a planet can support life is a primary goal of future exoplanet spectral characterization missions, but past research on habitability assessment has largely ignored the vastly different conditions that have existed in our planet's long habitable history. This study presents simulations of a habitable yet dramatically different phase of Earth's history, when the atmosphere contained a Titan-like, organic-rich haze. Prior work has claimed a haze-rich Archean Earth (3.8–2.5 billion years ago) would be frozen due to the haze's cooling effects. However, no previous studies have self-consistently taken into account climate, photochemistry, and fractal hazes. Here, we demonstrate using coupled climate-photochemical-microphysical simulations that hazes can cool the planet's surface by about 20 K, but habitable conditions with liquid surface water could be maintained with a relatively thick haze layer (τ ∼ 5 at 200 nm) even with the fainter young Sun. We find that optically thicker hazes are self-limiting due to their self-shielding properties, preventing catastrophic cooling of the planet. Hazes may even enhance planetary habitability through UV shielding, reducing surface UV flux by about 97% compared to a haze-free planet and potentially allowing survival of land-based organisms 2.7–2.6 billion years ago. The broad UV absorption signature produced by this haze may be visible across interstellar distances, allowing characterization of similar hazy exoplanets. The haze in Archean Earth's atmosphere was strongly dependent on biologically produced methane, and we propose that hydrocarbon haze may be a novel type of spectral biosignature on planets with substantial levels of CO 2 . Hazy Archean Earth is the most alien world for which we have geochemical constraints on environmental conditions, providing a useful analogue for similar habitable, anoxic exoplanets. Key Words: Haze—Archean Earth—Exoplanets—Spectra—Biosignatures—Planetary habitability. Astrobiology 16, 873–899.

AI snapshot

Written from the paper’s full text.

TL;DR

Coupled climate-photochemical-microphysical simulations of hazy Archean Earth show that organic haze can cool the surface by about 20 K but still permit habitable temperatures with liquid surface water, because thick hazes self-limit via UV self-shielding. The haze also strongly shields surface UV and produces distinctive spectral features, suggesting hydrocarbon haze may be a biologically mediated spectral biosignature on anoxic, CO₂-rich exoplanets.

Key findings

Hazy Archean climates were cold but likely habitable: for Cases A–D, stabilized surface temperatures with haze were 263, 274, 262, and 251 K, and with ice-albedo feedback 257, 271, 257, and 241 K, all above the adopted 248 K habitability threshold; haze cooling reached up to ∼20 K, with maximum haze optical thickness leveling off at τ ∼ 5 at 200 nm.
Haze is self-limiting: optically thicker hazes shield CH₄ from photolysis, shutting down haze formation and preventing catastrophic cooling; the CH₄/CO₂ ratios needed to initiate haze formation were 0.18, 0.15, 0.19, and 0.28 for Cases A–D.
UV shielding was substantial: for Case B with CH₄/CO₂ = 0.21, surface UVC flux was about 0.03 W/m² at SZA = 60° and 0.22 W/m² at SZA = 0°, compared with 0.93 and 2.62 W/m² for the haze-free case, a reduction of about 97%; this may have allowed survival of land-based organisms 2.7–2.6 billion years ago.
Hazy Archean Earth would be a “pale orange dot,” with a broad UV absorption signature, a 6 μm transit-transmission haze feature, and a weaker 3 μm feature; the CH₄ flux needed to initiate haze was about 1 × 10¹¹ to 3 × 10¹¹ molecules/cm²/s, far above estimated maximum abiotic serpentinization fluxes of 6.8 × 10⁸ and 1.3 × 10⁹ molecules/cm²/s for 1 and 5 Earth-mass rocky planets.

Methods

Used the coupled 1-D photochemical-climate model Atmos and the 1-D radiative transfer model SMART; the photochemical model has 200 plane-parallel layers from the surface to 100 km, 76 chemical species, and fractal hydrocarbon haze microphysics, while the climate model uses correlated-k absorption and a δ-2-stream radiative transfer scheme, iterating between models to convergence.
Simulated four Archean cases spanning pCO₂ = 0.0036–0.018 bar and surface pressure = 0.5–1 bar, with solar constant at 2.7 Ga = 0.81 S/S₀, surface O₂ = 1.0 × 10⁻⁸, and varied CH₄/CO₂; about 60 coupled Atmos runs were required.
Generated synthetic reflectance, thermal emission, and transit transmission spectra with SMART, including binned haze particle modes and, for Case B, tests with water clouds.

Limitations

Stated in paper: the climate model could only be run to about 80 km while the photochemical model extends to 100 km, with isoprofiles above the climate grid; sensitivity tests showed <5% difference in largest haze particles and <0.5 K surface temperature effect. Older CH₄ coefficients may overestimate surface temperature by ≲5 K, while the model underpredicts Archean temperature by about 2–5 K compared with 3-D models, so these may cancel.
Stated in paper: the 1-D model lacks atmospheric circulation, precipitation, cloud formation, cloud scattering and absorption, and long-wave cloud radiative forcing; comparison with GCMs suggests the presented temperatures may be underestimates by about 3–5 K, and ice-albedo feedback, haze deposition, haze circulation, and cloud feedbacks are left to future GCM studies.
Stated in paper and evident from text: haze formation chemistry is not well understood, and the model assumes C₄H₂ and C₅H₄ condense directly to haze particles, possibly overestimating aerosol formation; only one Archean haze refractive index measurement exists, at 532 nm, and the study uses Titan-like Khare optical constants; NH₃ was not included in the photochemical scheme; nominal haze spectra exclude water clouds.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1089/ast.2015.1422

Cites

138 of 138 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 147 cited sources checked · 0 supported · 0 flagged

In the paper
“The haze can produce a stronger UV shield compared to the low O2 atmosphere (0.1% PAL) proposed recently by Planavsky et al. (2014) for our atmospheric assumptions.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 3. Results > 3.2. UV shielding
What the sources say
- Not checked yetcites Planavsky et al., 2014
Load-bearingStrength:plain· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“By using the updated habitability threshold of Tsurf > 248 K, all our cases even with thick hazes are habitable.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 3. Results > 3.1. Hazy climates
Load-bearingStrength:plain· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
- Rests on an assumption: A planet with any nonzero fraction of open ocean is habitable.

Show all 153 claims

Probably not a substantial claim. 40
It may state two separate claims as one. 58

The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“We find that hazy Archean climates were cold but most likely habitable (Fig. 4).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 3. Results > 3.1. Hazy climates
Load-bearingStrength:hedged· not yet calibratedCausal:correlational· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
- Rests on an assumption: A planet with any nonzero fraction of open ocean is habitable.
In the paper
“its buildup in our spectra is not inconsistent with the results of Domagal-Goldman et al. (2011)”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 3. Results > 3.3. Spectra
What the sources say
- Not checked yetcites Domagal-Goldman et al. (2011)
Strength:plain· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“We achieve the closest match to the Charnay et al. results for a modern continental land mass arrangement: in the GCM, this yields an average albedo of 0.34 and a temperature of 283.7 K, close to our result of 281.1 K for this configuration.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 4. Discussion > 4.2. Comparison with other climate studies
What the sources say
- Not checked yetcites Charnay et al.
Strength:plain· not yet calibratedCausal:correlational· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passes
It may state two separate claims as one.
In the paper
“This difference in temperature is smaller than the difference of using spherical versus fractal particles: our comparison to the Haqq-Misra et al. (2008) study in Section 4.2 shows that particle shape can result in temperature differences >10 K.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 4. Discussion > 4.5. Optical constants
What the sources say
- Not checked yetcites Haqq-Misra et al. (2008)
Strength:plain· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passes
It may state two separate claims as one.
In the paper
“the modeling work of Domagal-Goldman et al. (2008) suggests a longer Mesoarchean to Neoarchean hazy period between 3.2 and 2.7 Ga.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 1. Introduction > 1.1. Evidence for an Archean haze
What the sources say
- Not checked yetcites Domagal-Goldman et al., 2008
Strength:hedged· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“S8 is the most important species to rain out S-MIF from the atmosphere; because a more reducing atmosphere enhances the ability of S8 to polymerize, S-MIF is more easily preserved under reducing conditions (Zahnle et al., 2006).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 1. Introduction > 1.1. Evidence for an Archean haze
What the sources say
- Not checked yetcites Zahnle et al., 2006
Load-bearingStrength:plain· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“Several studies have proposed links between haze and the mass-independent sulfur isotope fractionation signal (S-MIF) (Farquhar et al., 2000) preserved in the geological record before the Great Oxygenation Event (GOE) at about 2.5 Ga”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 1. Introduction > 1.1. Evidence for an Archean haze
What the sources say
- Not checked yetcites Farquhar et al., 2000
- Not checked yetcites Domagal-Goldman et al., 2008
- Not checked yetcites Zerkle et al., 2012
Load-bearingStrength:plain· not yet calibratedCausal:correlational· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
Probably not a substantial claim.
None of the sources cited for this claim have been checked yet.
In the paper
“Early in Earth's history, an anoxic atmosphere could have supported the formation of an organic haze (Pavlov et al., 2001a; Trainer et al., 2004, 2006; DeWitt et al., 2009; Hasenkopf et al., 2010; Zerkle et al., 2012; Kurzweil et al., 2013; Claire et al., 2014; Izon et al., 2015) that strongly interacted with visible and UV radiation, cooling the planet's climate (Pavlov et al., 2001b; Domagal-Gol”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 1. Introduction
What the sources say
- Not checked yetcites Pavlov et al., 2001a
- Not checked yetcites Trainer et al., 2004, 2006
- Not checked yetcites DeWitt et al., 2009
Load-bearingStrength:hedged· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“Δ36S/Δ33S in Archean sedimentary rocks is generally around −1, but stratigraphic variations in this slope have been observed in the geological record and interpreted as evidence of changes to the S-MIF production mechanism resulting from changes in atmospheric composition (Zerkle et al., 2012; Kurzweil et al., 2013; Izon et al., 2015), suggesting the influence of haze.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 1. Introduction > 1.1. Evidence for an Archean haze
What the sources say
- Not checked yetcites Zerkle et al., 2012
- Not checked yetcites Kurzweil et al., 2013
- Not checked yetcites Izon et al., 2015
Load-bearingStrength:hedged· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
In the paper
“In general, compared to spherical particles, fractal particles produce more extinction in the ultraviolet (UV) but less in the visible and near infrared (NIR).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 2. Models and Methods > 2.1. Coupled photochemical-climate model
What the sources say
- Not checked yetcites Wolf and Toon, 2010
Load-bearingStrength:plain· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
In the paper
“they discuss a change in the slope of Δ36S/Δ33S from −1.5 to −0.9 at 2.71 Ga and interpret this to be caused by a decrease in the CH4/CO2 ratio at 2.71 Ga, possibly indicating an organic haze was present for some period of time prior to 2.71 Ga and cleared afterward.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 1. Introduction > 1.1. Evidence for an Archean haze
What the sources say
- Not checked yetcites Kurzweil et al., 2013
Load-bearingStrength:hedged· not yet calibratedCausal:conditional· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
Probably not a substantial claim. It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“An upper atmosphere haze that decreased tropospheric SO2 photolysis by blocking UV photons and cooled the planet could explain both the glaciation and the decrease in S-MIF.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 1. Introduction > 1.1. Evidence for an Archean haze
What the sources say
- Not checked yetcites Domagal-Goldman et al., 2008
- Not checked yetcites Haqq-Misra et al., 2008
Load-bearingStrength:hedged· not yet calibratedCausal:conditional· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
Probably not a substantial claim.
None of the sources cited for this claim have been checked yet.
In the paper
“In this interpretation, haze-free and reducing atmospheric conditions dominated after 2.71 Ga, with haze reappearing in brief intervals of time as suggested by the Zerkle et al. (2012) and Izon et al. (2015) measurements.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 1. Introduction > 1.1. Evidence for an Archean haze
What the sources say
- Not checked yetcites Zerkle et al., 2012
- Not checked yetcites Izon et al., 2015
Load-bearingStrength:hedged· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“In a real atmosphere, the molecules would be larger before aerosols condense, and back-reactions should occur, so this model may overestimate the rate of aerosol formation.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 2. Models and Methods > 2.1. Coupled photochemical-climate model
Strength:hedged· not yet calibratedCausal:conditional· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. The paper’s conclusions may not depend on it.
- The authors state this as an assumption: C4H2 and C5H4 condense directly to haze particles.
In the paper
“Spherical particles in SMART are binned according to log-normal size distributions using the radii mentioned previously and a mode standard deviation of 1.5, which is realistic for an aerosol distribution (Tolfo, 1977).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 2. Models and Methods > 2.2. The SMART model
What the sources say
- Not checked yetcites Tolfo, 1977
Strength:plain· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“Note that the version of the model used here can simulate atmospheres ranging from extremely anoxic (pO2 = 10−14) to modern-day O2 levels (Zahnle et al., 2006).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 2. Models and Methods > 2.1. Coupled photochemical-climate model
What the sources say
- Not checked yetcites Zahnle et al., 2006
Strength:plain· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“In addition, fractals tend to be more forward scattering in the visible and NIR and more isotropically scattering in the UV compared to equal-mass spherical particles.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 2. Models and Methods > 2.1. Coupled photochemical-climate model
What the sources say
- Not checked yetcites Wolf and Toon, 2010
Load-bearingStrength:plain· not yet calibratedCausal:correlational· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
In the paper
“Δ33S typically correlates with enrichments in δ34S and with depletions in δ36S”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 1. Introduction > 1.1. Evidence for an Archean haze
What the sources say
- Not checked yetcites Claire et al., 2014
Strength:plain· not yet calibratedCausal:correlational· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passes
It may state two separate claims as one.
In the paper
“In this conceptual model, the end of the cold period typified by low Δ33S may be due to a decrease in the atmospheric CH4/CO2 ratio, which would have cleared any haze present in the atmosphere.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 1. Introduction > 1.1. Evidence for an Archean haze
What the sources say
- Not checked yetcites Claire et al., 2014
Load-bearingStrength:hedged· not yet calibratedCausal:conditional· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
Probably not a substantial claim.
In the paper
“Unlike previous studies of the Archean climate under a haze, we use realistic fractal (rather than spherical) particles, which have different spectral properties and climatic effects.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 1. Introduction > 1.1. Evidence for an Archean haze
What the sources say
- Not checked yetcites Wolf and Toon, 2010
Load-bearingStrength:plain· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“Kurzweil et al. (2013) noted that an increase in magnitude of S-MIF signals after 2.73 Ga (Thomazo et al., 2009) occurred during a prolonged negative shift in δ13Corg, suggesting enhanced biological methane activity at this time.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 1. Introduction > 1.1. Evidence for an Archean haze
What the sources say
- Not checked yetcites Kurzweil et al., 2013
- Not checked yetcites Thomazo et al., 2009
Strength:hedged· not yet calibratedCausal:correlational· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. The paper’s conclusions may not depend on it.
None of the sources cited for this claim have been checked yet.
In the paper
“However, more recent 3-D studies have shown that Archean Earth can maintain an open ocean fraction of >50% for TGAT ≥ 260 K and an equatorial open ocean belt for TGAT ≥ 248 K (Wolf and Toon, 2013; Charnay et al., 2013).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 3. Results > 3.1. Hazy climates
What the sources say
- Not checked yetcites Wolf and Toon, 2013
- Not checked yetcites Charnay et al., 2013
Load-bearingStrength:plain· not yet calibratedCausal:conditional· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
In the paper
“This might lead to cooling of the planet or even warming depending on cloud particle size and the altitude—and therefore temperature—of the cloud layer (Goldblatt and Zahnle, 2011).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 3. Results > 3.1. Hazy climates
What the sources say
- Not checked yetcites Goldblatt and Zahnle, 2011
Strength:hedged· not yet calibratedCausal:conditional· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passes
It may state two separate claims as one.
In the paper
“but a recent study of chromium isotopes suggests that the Proterozoic O2 mixing ratio was, at most, 0.1% PAL (Planavsky et al., 2014).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 3. Results > 3.2. UV shielding
What the sources say
- Not checked yetcites Planavsky et al., 2014
Load-bearingStrength:hedged· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
Probably not a substantial claim.
None of the sources cited for this claim have been checked yet.
In the paper
“Later purported hazy periods around 2.7 Ga (Kurzweil et al., 2013; Izon et al., 2015) and between 2.65 and 2.5 Ga (Zerkle et al., 2012) are not associated with glaciations and may be consistent with the thinner-haze solution space of Cases A and C or even the thickest haze solution space of the warmer Case B.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 3. Results > 3.1. Hazy climates
What the sources say
- Not checked yetcites Kurzweil et al., 2013
- Not checked yetcites Izon et al., 2015
- Not checked yetcites Zerkle et al., 2012
Load-bearingStrength:hedged· not yet calibratedCausal:correlational· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“DNA damage is most acute in the UVC (λ < 0.28 μm) wavelength range (Pierson et al., 1992; Dillon and Castenholz, 1999), but in the modern atmosphere, UVC is fully blocked by O2 and ozone.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 3. Results > 3.2. UV shielding
What the sources say
- Not checked yetcites Pierson et al., 1992
- Not checked yetcites Dillon and Castenholz, 1999
Load-bearingStrength:plain· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
In the paper
“Unless otherwise specified, the surface albedo used by the climate model is 0.32. This includes the effect of clouds, which is standard in this 1-D treatment (Kopparapu et al., 2013) and is the albedo that reproduces the average temperature of present-day Earth (288 K) with modern atmospheric conditions.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 2. Models and Methods > 2.3. Model inputs
What the sources say
- Not checked yetcites Kopparapu et al., 2013
Strength:plain· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
In the paper
“We set the mixing ratio of O2 at the surface to 1.0 × 10−8, consistent with the Zerkle et al. (2012) study.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 2. Models and Methods > 2.3. Model inputs
What the sources say
- Not checked yetcites Zerkle et al., 2012
Load-bearingStrength:plain· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
Probably not a substantial claim.
In the paper
“Furthermore, Abbot et al. (2011) argued that ocean open belts can remain climatologically stable, even if the ice latitude is reduced to 5–15°.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 3. Results > 3.1. Hazy climates
What the sources say
- Not checked yetcites Abbot et al., 2011
Load-bearingStrength:plain· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
Probably not a substantial claim.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Because methane-producing metabolisms evolved early and Earth's atmosphere was anoxic for about a billion years after the origin of life, pale orange dots may proliferate in the Galaxy if other habitable worlds evolve on similar paths to Earth.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 3. Results > 3.3. Spectra
Strength:hedged· not yet calibratedCausal:conditional· not yet calibratedSingle case
Tests✓ Asserted: passes✗ Checkable: fails✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. It may be too vague to check against evidence. The paper’s conclusions may not depend on it. It may state two separate claims as one.
- Rests on an assumption: Methane-producing metabolisms evolved early.
- Rests on an assumption: Earth's atmosphere was anoxic for about a billion years after the origin of life.
In the paper
“Of course, the true cloud distribution on Archean Earth is unknown, and clouds may have had important climatic effects on our early planet (Goldblatt and Zahnle, 2011).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 2. Models and Methods > 2.3. Model inputs
What the sources say
- Not checked yetcites Goldblatt and Zahnle, 2011
Strength:hedged· not yet calibratedCausal:conditional· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
In the paper
“The solar zenith angles (SZAs) used in the climate and photochemical models were chosen to best represent globally averaged behavior of the physics in each specific model, which Segura et al. (2003) found as SZA = 45° in the photochemical model and SZA = 60° in the climate model. These zenith angles are both tuned to reproduce modern-day Earth's average chemical profiles and climate, respectively.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 2. Models and Methods > 2.3. Model inputs
What the sources say
- Not checked yetcites Segura et al., 2003
Load-bearingStrength:plain· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“The impact of these hazes on the biosphere goes beyond temperature reduction: their fractal nature makes them strong absorbers at short wavelengths and therefore a potential shield against damaging UV radiation for the anoxic Archean (Wolf and Toon, 2010), which would have received significantly more UV at the surface than the planet today (Rugheimer et al., 2015).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 3. Results > 3.2. UV shielding
What the sources say
- Not checked yetcites Wolf and Toon, 2010
- Not checked yetcites Rugheimer et al., 2015
Load-bearingStrength:hedged· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
In the paper
“which showed much greater C2H6 accumulation on planets orbiting low-mass stars compared to worlds orbiting the Sun.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 3. Results > 3.3. Spectra
What the sources say
- Not checked yetcites Domagal-Goldman et al. (2011)
Strength:plain· not yet calibratedCausal:correlational· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“Based on their calculations, Guzmán-Marmolejo et al. (2013) suggested that an atmospheric CH4 concentration greater than 10 ppmv is suggestive of life.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 4. Discussion > 4.1. Haze and biology
What the sources say
- Not checked yetcites Guzmán-Marmolejo et al. (2013)
Load-bearingStrength:hedged· not yet calibratedCausal:correlational· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
Probably not a substantial claim.
In the paper
“The Charnay et al. results for the same atmospheric properties but with an equatorial supercontinent result in the same overall planetary albedo (0.33) but a lower mean temperature of 285 K”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 4. Discussion > 4.2. Comparison with other climate studies
What the sources say
- Not checked yetcites Charnay et al.
Strength:plain· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passes
It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“Laboratory experiments on organic haze formation have shown that haze-formation chemistry can involve the formation of important prebiotic molecules such as amino acids and nucleotide bases (Khare et al., 1986; McDonald et al., 1994; DeWitt et al., 2009; Hörst et al., 2012; Trainer, 2013)”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 4. Discussion > 4.1. Haze and biology
What the sources say
- Not checked yetcites Khare et al., 1986
- Not checked yetcites McDonald et al., 1994
- Not checked yetcites DeWitt et al., 2009
Strength:plain· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“We also tested our model results against the Community Atmosphere Model (CAM) GCM nominal Archean atmosphere reported by Wolf and Toon (2013).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 4. Discussion > 4.2. Comparison with other climate studies
What the sources say
- Not checked yetcites Wolf and Toon (2013)
Load-bearingStrength:plain· not yet calibratedSingle case
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
Probably not a substantial claim.
In the paper
“C2H6 is a greenhouse gas, and its ability to warm in a CH4- and haze-rich atmosphere has been discussed previously (Haqq-Misra et al., 2008).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 3. Results > 3.3. Spectra
What the sources say
- Not checked yetcites Haqq-Misra et al., 2008
Strength:plain· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
In the paper
“The Mahjoub study tested the impact of methane concentration in the gas phase on the resultant hydrocarbon optical properties with gas mixtures containing 1%, 2%, 5%, and 10% CH4 in CH4-N2 mixtures.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 4. Discussion > 4.5. Optical constants
What the sources say
- Not checked yetcites Mahjoub et al.
Strength:plain· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. The paper’s conclusions may not depend on it.
None of the sources cited for this claim have been checked yet.
In the paper
“Following Sagan and Chyba (1997), Wolf and Toon calculated a NH3 atmospheric lifetime of 7 × 107 years for a solar incident flux at a 45° angle assuming τ ∼ 11 at 200 nm.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 4. Discussion > 4.3. Potential for NH3 greenhouse gas shielding
What the sources say
- Not checked yetcites Sagan and Chyba (1997)
- Not checked yetcites Wolf and Toon
Load-bearingStrength:plain· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
Probably not a substantial claim.
In the paper
“As an example and test of the impact different refractive indices have on our spectra, we examined the sensitivity of our nominal spectra to varied refractive indices measured by Mahjoub et al. (2012).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 4. Discussion > 4.5. Optical constants
What the sources say
- Not checked yetcites Mahjoub et al. (2012)
Strength:plain· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“Mass spectrometry of aerosol analogues formed with C/O = 0.1 indicates the formation of carbonyl and carboxyl groups rather than aromatic cycles and long-aliphatic chains, and even suggests the formation of organic acids such as succinic acid (C4H6O4) (DeWitt et al., 2009).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 4. Discussion > 4.4. Haze formation pathways
What the sources say
- Not checked yetcites DeWitt et al., 2009
Load-bearingStrength:hedged· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
In the paper
“Unfortunately, only one study, that of Hasenkopf et al. (2010), has measured an Archean Earth haze refractive index (as opposed to a titanian haze), and this was only done at a single wavelength (532 nm).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 4. Discussion > 4.5. Optical constants
What the sources say
- Not checked yetcites Hasenkopf et al. (2010)
Load-bearingStrength:plain· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“Early Earth's atmosphere would have contained negligible O2 but significant amounts of CO2 (e.g., Kasting, 1993; Driese et al., 2011), whereas Titan's atmosphere is extremely reducing (de Kok et al., 2007).”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 4. Discussion > 4.4. Haze formation pathways
What the sources say
- Not checked yetcites Kasting, 1993
- Not checked yetcites Driese et al., 2011
- Not checked yetcites de Kok et al., 2007
Load-bearingStrength:hedged· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes
It may state two separate claims as one.
None of the sources cited for this claim have been checked yet.
In the paper
“In situ measurements by several instruments on board Cassini have found direct evidence for long hydrocarbons and nitriles chains, benzene (C6H6) and toluene (C6H5CH3), and indirect evidence for polycyclic aromatic hydrocarbons (PAHs) and nitrogen-containing polycyclic aromatic hydrocarbons (PANHs), indicating that these compounds might play a role in the formation of Titan's hazes (Waite et al.,”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 4. Discussion > 4.4. Haze formation pathways
What the sources say
- Not checked yetcites Waite et al., 2007
- Not checked yetcites López-Puertas et al., 2013
Strength:hedged· not yet calibratedCausal:conditional· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
In the paper
“Wolf and Toon (2010) commented on the possibility of a fractal hydrocarbon haze shielding ammonia (NH3) from photolysis, allowing this greenhouse gas to build up in the Archean atmosphere.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 4. Discussion > 4.3. Potential for NH3 greenhouse gas shielding
What the sources say
- Not checked yetcites Wolf and Toon (2010)
Strength:hedged· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passes
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“Mahjoub et al. found that refractive indices have a strong dependency on the CH4 concentration over 0.37–1 μm: results indicate that the imaginary index of refraction (k) decreases with increasing CH4 concentration, and the real index of refraction (n) increases with CH4 for the compositions tested.”
§ The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth > 4. Discussion > 4.5. Optical constants
What the sources say
- Not checked yetcites Mahjoub et al.
Strength:boosted· not yet calibratedCausal:direct· not yet calibrated
Tests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passes
It may state two separate claims as one.

89 of 89

The authors state this as an assumption.
Fixed isoprofiles are assumed for CO2 and N2 in the atmospheres considered here.
“Fixed isoprofiles are assumed for CO2 and N2 in the atmospheres considered here.”
The authors state this as an assumption.
C4H2 and C5H4 condense directly to haze particles.
“it is assumed that C4H2 and C5H4 condense directly to haze particles (called HCAER and HCAER2 in Supplementary Table S1).”
The paper relies on this without support.
A planet with any nonzero fraction of open ocean is habitable.
“Since a planet with any nonzero fraction of open ocean is habitable, we regard these updated globally averaged temperatures—all of which are significantly below freezing—to be more realistic habitability thresholds than 273 K.”
The paper relies on this without support.
Methane-producing metabolisms evolved early.
“Because methane-producing metabolisms evolved early and Earth's atmosphere was anoxic for about a billion years after the origin of life, pale orange dots may proliferate in the Galaxy if other habitable worlds evolve on similar paths to Earth.”
The paper relies on this without support.
Earth's atmosphere was anoxic for about a billion years after the origin of life.
“Because methane-producing metabolisms evolved early and Earth's atmosphere was anoxic for about a billion years after the origin of life, pale orange dots may proliferate in the Galaxy if other habitable worlds evolve on similar paths to Earth.”
The paper relies on this without support.
Water vapor clouds have an approximately gray opacity from the visible into the NIR.
“water vapor clouds have an approximately gray opacity from the visible into the NIR.”
The paper relies on this without support.
The tropopause on Earth is at roughly 10 km.
“The tropopause on Earth is at roughly 10 km”
The paper relies on this without support.
Geochemical evidence suggests hazy conditions were not present throughout the entire Archean.
“geochemical evidence suggests hazy conditions were not present throughout the entire Archean”
The paper relies on this without support.
The geochemical constraints on Archean CO2 concentration and geological constraints on surface pressure used in the study are valid.
“consistent with geochemical constraints on CO2 concentration and geological constraints on surface pressure”
The paper relies on this without support.
UVC radiation is harmful to unshielded life.
“may have allowed survival of otherwise unshielded life at the surface of our Archean planet”

10 of 10

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

Conflicting criteria for haze-particle growth
Minor
The methods say particles can grow when the coagulation lifetime is longer than the removal lifetime, but the results say growth occurs when the coagulation timescale is shorter than the removal timescale.
Sulfur isotope relationship uses the wrong isotope on its right-hand side
Minor
The text says δ36S is roughly twice δ34S, but the stated mass-dependent relationship makes δ36S proportional to itself instead.
Example does not give equal log-space bin distances
Minor
The stated binning rule uses distance in log space, but 0.33 μm is not halfway in log space between 0.3 and 0.4 μm. Those bins therefore would not each receive 50% of the mass under the stated rule.

3 of 3

Phylogenetic structure of the prokaryotic domain: The primary kingdoms
Woese, C. R., & Fox, G. E. (1977) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.74.11.5088 · Cited by 4,131 · cited 2×
“5 billion years ago) haze was likely biologically mediated via CH4 produced from methanogenesis, one of the earliest metabolisms (Woese and Fox, 1977; Ueno et al., 2006).”
Influential
The formation, properties and impact of secondary organic aerosol: current and emerging issues
Hallquist, M., Wenger, J., Baltensperger, U., Rudich, Y., Simpson, D. M., Claeys, M., Dommen, J., Donahue, N. M., George, C., Goldstein, A. H., et al. (2009) · Atmospheric chemistry and physics · doi:10.5194/acp-9-5155-2009 · Cited by 4,039 · cited 1×
“Since the full chemical scheme that leads to aerosol formation is not well understood despite both laboratory and theoretical studies ( e.g. , Hallquist et al. , 2009; Hicks et al. , 2015), it is assumed that C 4 H 2 and C 5 H 4 condense directly to haze particles (called HCAER and HCAER2 in…”
The HITRAN2012 molecular spectroscopic database
Rothman, L. S., Gordon, I. E., Babikov, Y., Barbe, A., Chris Benner, D., Bernath, P. F., Birk, M., Bizzocchi, L., Boudon, V., Brown, L. R., et al. (2013) · Journal of Quantitative Spectroscopy and Radiative Transfer · doi:10.1016/j.jqsrt.2013.07.002 · Cited by 3,255 · cited 1×
“The Line-by-Line Absorption Coefﬁcients (LBLABC) code, a companion to SMART, creates line-by-line absorption ﬁles for input gas mixing ratios and temperature-pressure proﬁles using HITRAN 2012 line lists (Rothman et al. , 2013).”
Diffuse radiation in the Galaxy
Henyey, L. C., & Greenstein, J. L. (1941) · The Astrophysical Journal · doi:10.1086/144246 · Cited by 2,971 · cited 1×
“Spherical particles use a full Mie phase function, while fractal particles employ a Henyey-Greenstein phase function (Henyey and Greenstein, 1941).”
Atmospheric Influence of Earth's Earliest Sulfur Cycle
Farquhar, J., Bao, H., & Thiemens, M. (2000) · Science · doi:10.1126/science.289.5480.756 · Cited by 1,805 · cited 16×
“Thus, S-MIF is generally regarded as robust evidence for an anoxic Archean atmosphere.”
Influential
HABITABLE ZONES AROUND MAIN-SEQUENCE STARS: NEW ESTIMATES
Kopparapu, R. K., Ramirez, R., Kasting, J. F., Eymet, V., Robinson, T. D., Mahadevan, S., Terrien, R. C., Domagal-Goldman, S., Meadows, V., & Deshpande, R. (2013) · The Astrophysical Journal · doi:10.1088/0004-637x/765/2/131 · Cited by 1,615 · cited 7×
“The version we use here is based directly on that used by Kopparapu et al. (2013).”
InfluentialSelf-citation
Earth's Early Atmosphere
Kasting, J. F. (1993) · Science · doi:10.1126/science.11536547 · Cited by 1,374
A Serpentinite-Hosted Ecosystem: The Lost City Hydrothermal Field
Kelley, D. S., Karson, J. A., Früh-Green, G. L., Yoerger, D. R., Shank, T. M., Butterfield, D. A., Hayes, J. M., Schrenk, M. O., Olson, E. J., Proskurowski, G., et al. (2005) · Science · doi:10.1126/science.1102556 · Cited by 1,288 · cited 1×
“In addition, several abiotic processes including serpentinization (the hydration of ultramaﬁc rocks, mainly olivine and pyroxenes) can form methane (Kelley et al. , 2005; Etiope and Sherwood Lollar, 2013; Guzma´n-Marmolejo et al. , 2013), but the biotic ﬂux of methane to the Archean atmosphere was…”
Photochemistry of the atmosphere of Titan - Comparison between model and observations
Yung, Y. L., Allen, M., & Pinto, J. P. (1984) · The Astrophysical Journal Supplement Series · doi:10.1086/190963 · Cited by 1,081 · cited 2×
“Following the mechanism proposed for the formation of Titan’s hydrocarbon haze (Allen et al. , 1980; Yung et al. , 1984), every model of hydrocarbon haze formation in early Earth’s atmosphere—including ours—has assumed that aerosol formation will occur through the formation of acetylene (C 2 H 2 )…”
Clouds in the atmosphere of the super-Earth exoplanet GJ 1214b
Kreidberg, L., Bean, J. L., Désert, J.-M., Benneke, B., Deming, D., Stevenson, K. B., Seager, S., Berta-Thompson, Z. K., Seifahrt, A., & Homeier, D. (2013) · Nature · doi:10.1038/nature12888 · Cited by 938 · cited 2×
“Unlike the hazes that may exist around exoplanets with thick hydrogen-dominated atmospheres (Sing et al., 2011; Knutson et al., 2014; Kreidberg et al., 2014), the Archean (3.”
Influential

Flagged first, then by citations

Show all 136 references

Research works printed but not linked: 5

10.1051/0004-6361/201014343 · DOI
Schopf J.W., editor. (1983) Earth's Earliest Biosphere: Its Origin and Evolution, Princeton University Press, Princeton, NJ.
Sciamma-O'Brien E., , Dahoo P.-R., , Hadamcik E., , Carrasco N., , Quirico E., , Szopa C., , and Cernogora G. (2012) Optical constants from 370nm to 900nm of Titan tholins produced in a low pressure RF plasma discharge. Icarus, 218:353–363.
Traub W.A. (2003) Extrasolar planet characteristics in the visible wavelength range. In Proceedings of the Conference on Towards Other Earths: DARWIN/TPF and the Search for Extrasolar Terrestrial Planets, Heidelberg, Germany, pp 231–239.
Workman J., editor. (2000) The Handbook of Organic Compounds, Three-Volume Set: NIR, IR, R, and UV-Vis Spectra Featuring Polymers and Surfactants, Academic Press, San Diego, CA.

Sorted by citations

Living at the Extremes: Extremophiles and the Limits of Life in a Planetary Context
Merino, N., Aronson, H. S., Bojanova, D. P., Feyhl‐Buska, J., Wong, M. L., Zhang, S. J., & Giovannelli, D. (2019) · Frontiers in Microbiology · doi:10.3389/fmicb.2019.00780 · Cited by 707
The Archean atmosphere
Catling, D. C., & Zahnle, K. J. (2020) · Science Advances · doi:10.1126/sciadv.aax1420 · Cited by 568
“Thus, attenuation of sunlight saturates (1, 163).”
Background
Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life
Schwieterman, E. W., Kiang, N. Y., Parenteau, M. N., Harman, C. E., DasSarma, S., Fisher, T. M., Arney, G. N., Hartnett, H. E., Reinhard, C. T., Olson, S. L., et al. (2018) · Astrobiology · doi:10.1089/ast.2017.1729 · Cited by 630
“…al., 2013), a purple Archean ocean due to photosynthetic purple bacteria (Sanromá et al., 2014); an orange Archean Earth due to an organic-rich atmospheric haze (Arney et al., 2016); and trajectories of O2 fluxes over geologic time given estimated atmospheric concentrations (Gebauer et al., 2017).”
BackgroundMethodInfluentialSelf-citation
Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life
Schwieterman, E. W., Kiang, N. Y.-L., Parenteau, M. N., Harman, C. E., DasSarma, S., Fisher, T. M., Arney, G., Hartnett, H. E., Reinhard, C. T., Olson, S. L., et al. (2017) · eScholarship (California Digital Library) · Cited by 452
Self-citation
Exoplanet Biosignatures: Understanding Oxygen as a Biosignature in the Context of Its Environment
Meadows, V., Reinhard, C. T., Arney, G., Parenteau, M. N., Schwieterman, E. W., Domagal-Goldman, S. D., Lincowski, A., Stapelfeldt, K. R., Rauer, H., DasSarma, S., et al. (2018) · Astrobiology · doi:10.1089/ast.2017.1727 · Cited by 341
“Such hazes may have been present during early periods of Earth’s history when the atmosphere was more reducing (Arney et al., 2016).”
BackgroundMethodSelf-citation
Impact of space weather on climate and habitability of terrestrial-type exoplanets
Airapetian, V. S., Barnes, R., Cohen, O., Collinson, G. A., Danchi, W. C., Dong, C., C, A. D. D. G., France, K., Garcia-Sage, K., Glocer, A., et al. (2019) · International Journal of Astrobiology · doi:10.1017/s1473550419000132 · Cited by 288
How to Characterize Habitable Worlds and Signs of Life
Kaltenegger, L. (2017) · Annual Review of Astronomy and Astrophysics · doi:10.1146/annurev-astro-082214-122238 · Cited by 256
Modeling Repeated M Dwarf Flaring at an Earth-like Planet in the Habitable Zone: Atmospheric Effects for an Unmagnetized Planet
Tilley, M. A., Segura, A., Meadows, V., Hawley, S., & Davenport, J. (2018) · Astrobiology · doi:10.1089/ast.2017.1794 · Cited by 271
“In an early-Earth-type anoxic atmosphere, Arney et al. (2016) showed that the presence of haze can cut the incident UVC radiation at the surface of the planet by a factor of *30 with a solar zenith angle of 60 .”
BackgroundInfluentialSelf-citation
Exoplanet Biosignatures: A Framework for Their Assessment
Catling, D. C., Krissansen-Totton, J., Kiang, N. Y., Crisp, D., Robinson, T. D., DasSarma, S., Rushby, A. J., Del Genio, A., Bains, W., & Domagal-Goldman, S. (2018) · Astrobiology · doi:10.1089/ast.2017.1737 · Cited by 225
“1, and there is adequate UV flux from the star, an organic haze is produced (Trainer et al., 2006; Haqq-Misra et al., 2008; Arney et al., 2016), which may decrease biological productivity through an antigreenhouse effect on the climate (Haqq-Misra et al.”
BackgroundMethodInfluentialSelf-citation
Fungi are key players in extreme ecosystems
Coleine, C., Stajich, J., & Selbmann, L. (2022) · Trends in Ecology & Evolution · doi:10.1016/j.tree.2022.02.002 · Cited by 208
Habitable Moist Atmospheres on Terrestrial Planets near the Inner Edge of the Habitable Zone around M Dwarfs
Kopparapu, R., Wolf, E. T., Arney, G., Batalha, N. E., Haqq-Misra, J. D., Grimm, S. L., & Heng, K. (2017) · The Astrophysical Journal · doi:10.3847/1538-4357/aa7cf9 · Cited by 213
“It has been validated against solar system objects (Arney et al. 2014; Robinson et al. 2014) and has been used to study a wide variety of types of atmospheres (Robinson et al. 2011; Arney et al. 2016; Schwieterman et al. 2016; Charnay et al. 2015).”
MethodSelf-citation
Modeling climate diversity, tidal dynamics and the fate of volatiles on TRAPPIST-1 planets
Turbet, M., Bolmont, É., Leconte, J., Forget, F., Selsis, F., Tobie, G., Caldas, A., Naar, J., & Gillon, M. (2018) · Astronomy and Astrophysics · doi:10.1051/0004-6361/201731620 · Cited by 211
“We acknowledge however that the arguments stated in the previous section (especially the haze negative feedback on CH4 photolysis, as proposed by Arney et al. 2016) could drastically limit the CH4 photolysis rate and relax the constraint on the methane production rate required to sustain a CH4-rich…”
BackgroundMethod
Science Goals and Objectives for the Dragonfly Titan Rotorcraft Relocatable Lander
Barnes, J. W., Turtle, E. P., Trainer, M. G., Lorenz, R. D., MacKenzie, S., Brinckerhoff, W. B., Cable, M. L., Ernst, C. M., Freissinet, C., Hand, K. P., et al. (2021) · The Planetary Science Journal · doi:10.3847/psj/abfdcf · Cited by 236
Self-citation
Strange messenger: a new history of hydrogen on Earth, as told by xenon
Zahnle, K. J., Gacesa, M., & Catling, D. C. (2019) · Geochimica et Cosmochimica Acta · doi:10.1016/j.gca.2018.09.017 · Cited by 175
“This partiality to life as an ion would change if O2 were abundant, as was certainly the case after the GOE (Great Oxidation Event) ca 2.4-2.1 Ga (Catling and Kasting, 2017, p. 257), or if small hydrocarbons (other than CH4) were abundant, as could have been the case if Archean Earth experienced a Titan-like pale oran…”
BackgroundInfluential
Reflections on O 2 as a Biosignature in Exoplanetary Atmospheres
Meadows, V. S. (2017) · Astrobiology · doi:10.1089/ast.2016.1578 · Cited by 173
“…observation, direct imaging observations complement transmission observations because they can see much deeper into a planetary atmosphere, and possibly all the way to the surface—and are less sensitive to the attenuating effects of hazes and other upper atmospheric absorbers (Arney et al., 2016).”
BackgroundInfluentialSelf-citation
Exoplanet Biosignatures: Observational Prospects
Fujii, Y., Angerhausen, D., Deitrick, R., Domagal-Goldman, S., Grenfell, J. L., Hori, Y., Kane, S. R., Pallé, E., Rauer, H., Siegler, N., et al. (2018) · Astrobiology · doi:10.1089/ast.2017.1733 · Cited by 185
“At longer wavelengths, transmission spectra are less sensitive to high-altitude haze particles due to the reduced extinction efficiency (e.g., Hu et al., 2013; Arney et al., 2016).”
BackgroundInfluentialSelf-citation
When Did Life Likely Emerge on Earth in an RNA‐First Process?
Benner, S. A., Bell, E. A., Biondi, E., Brasser, R., Carell, T., Kim, H., Mojzsis, S. J., Omran, A., Pasek, M. A., & Trail, D. (2020) · ChemSystemsChem · doi:10.1002/syst.201900035 · Cited by 162
Evolved Climates and Observational Discriminants for the TRAPPIST-1 Planetary System
Lincowski, A., Meadows, V. S., Crisp, D., Robinson, T. D., Luger, R., Lustig‐Yaeger, J., & Arney, G. (2018) · The Astrophysical Journal · doi:10.3847/1538-4357/aae36a · Cited by 163
“…we couple VPL Climate to a publicly available atmospheric chemistry model.6 This code is based on Kasting et al. (1979) and Zahnle et al. (2006) and can simulate a range of planetary redox states, including high-oxygen atmospheres (Arney et al. 2016; Schwieterman et al. 2016; Meadows et al. 2018a).”
BackgroundMethodSelf-citation
Impact of Clouds and Hazes on the Simulated JWST Transmission Spectra of Habitable Zone Planets in the TRAPPIST-1 System
Fauchez, T. J., Turbet, M., Villanueva, G. L., Wolf, E. T., Arney, G., Kopparapu, R., Lincowski, A., Mandell, A. M., de Wit, J., Pidhorodetska, D., et al. (2019) · The Astrophysical Journal · doi:10.3847/1538-4357/ab5862 · Cited by 143
“For planets for which the ratio of methane over carbon dioxide (CH4/CO2) in the atmosphere exceeds about 0.1, haze formation can occur (Arney et al. 2016).”
BackgroundMethodInfluentialSelf-citation
Exoplanet Biosignatures: Observational Prospects
Fujii, Y., Angerhausen, D., Deitrick, R., Domagal-Goldman, S. D., Grenfell, J. L., Hori, Y., Kane, S. R., Πάλλη, Ε., Rauer, H., Siegler, N., et al. (2018) · doi:10.7892/boris.126822 · Cited by 162
Self-citation
The Habitability of Proxima Centauri b: Environmental States and Observational Discriminants
Meadows, V. S., Arney, G., Schwieterman, E. W., Lustig‐Yaeger, J., Lincowski, A., Robinson, T., Domagal-Goldman, S. D., Deitrick, R., Barnes, R. K., Fleming, D. P., et al. (2018) · Astrobiology · doi:10.1089/ast.2016.1589 · Cited by 164
“However, 3-D GCM studies have shown that Archean Earth can maintain an open ocean fraction of >50%, and thereby remain habitable, for globally averaged surface temperatures as low as 260 K (Wolf and Toon, 2013; Arney et al., 2016), and an equatorial belt of open ocean may also be possible for globally averaged surface…”
BackgroundMethodInfluentialSelf-citation
Pale Orange Dots: The Impact of Organic Haze on the Habitability and Detectability of Earthlike Exoplanets
Arney, G., Meadows, V. S., Domagal-Goldman, S. D., Deming, D., Robinson, T. D., Mendoza, G. T., Wolf, E. T., & Schwieterman, E. W. (2017) · The Astrophysical Journal · doi:10.3847/1538-4357/836/1/49 · Cited by 179
“Particle coagulation proceeds more efficiently in hotter atmospheres, leading to larger particles (Arney et al. 2016).”
BackgroundMethodResultInfluentialSelf-citation
Optical properties of potential condensates in exoplanetary atmospheres
Kitzmann, D., & Heng, K. (2017) · Monthly Notices of the Royal Astronomical Society · doi:10.1093/mnras/stx3141 · Cited by 134
“This was done, for example, for fractal haze particles in the atmosphere of the early Earth by Arney et al. (2016) or to describe non-spherical water ice cloud crystals in Earth-like atmospheres by Kitzmann et al. (2010).”
Background
Atmospheric Escape Processes and Planetary Atmospheric Evolution
Gronoff, G., Arras, P., Baraka, S., Bell, J. M., Cessateur, G., Cohen, O., Curry, S. M., Drake, J. J., Elrod, M. K., Erwin, J. T., et al. (2020) · Journal of Geophysical Research Space Physics · doi:10.1029/2019ja027639 · Cited by 173
Co‐evolution of early Earth environments and microbial life
Lyons, T. W., Tino, C., Fournier, G. P., Anderson, R. E., Leavitt, W. D., Konhauser, K. O., & Stüeken, E. E. (2024) · Nature Reviews Microbiology · doi:10.1038/s41579-024-01044-y · Cited by 141
“However, there are both direct and indirect contextual observations suggesting high concentrations of methane (potentially producing organic hazes such as those on Titan, Saturn’s largest moon 168 ) in the Archaean atmosphere.”
Phosphine as a Biosignature Gas in Exoplanet Atmospheres
Sousa‐Silva, C., Seager, S., Ranjan, S., Petkowski, J. J., Zhan, Z., Hu, R., & Bains, W. (2019) · Astrobiology · doi:10.1089/ast.2018.1954 · Cited by 144
“Organic hazes are predicted to form at [CH 4 ]/[CO 2 ] > 0.12 for M dwarf stars, and [CH 4 ]/[CO 2 ] ‡ 0.2 for Sun-like stars (Arney et al. , 2016, 2017).”
Influential
Detectability of atmospheric features of Earth-like planets in the habitable zone around M dwarfs
Wunderlich, F., Godolt, M., Grenfell, J. L., Städt, S., Smith, A. M. S., Gebauer, S., Schreier, F., Hedelt, P., & Rauer, H. (2019) · Astronomy and Astrophysics · doi:10.1051/0004-6361/201834504 · Cited by 115
“Including thick hazes would likely decrease the surface temperature by a few degr es (see e.g. Arney et al. 2016, 2017).”
BackgroundInfluential
Aerosols in Exoplanet Atmospheres
Gao, P., Wakeford, H. R., Moran, S. E., & Parmentier, V. (2021) · Journal of Geophysical Research Planets · doi:10.1029/2020je006655 · Cited by 127
Anomalous fractionation of mercury isotopes in the Late Archean atmosphere
Zerkle, A. L., Yin, R., Chen, C., Li, X. D., Izon, G., & Grasby, S. E. (2020) · Nature Communications · doi:10.1038/s41467-020-15495-3 · Cited by 100
Atmospheric regimes and trends on exoplanets and brown dwarfs
Zhang, X. (2020) · Research in Astronomy and Astrophysics · doi:10.1088/1674-4527/20/7/99 · Cited by 104
“…compositions of terrestrial exoplanetary atmospheres and the interpretation of their spectra (e.g., Selsis et al. 2002; Segura et al. 2005; Segura et al. 2007; Hu et al. 2012, 2013; Rugheimer et al. 2015; Arney et al. 2016, 2017; Meadows et al. 2018; Lincowski et al. 2018; Chen et al. 2019).”
Background
The case and context for atmospheric methane as an exoplanet biosignature
Thompson, M., Krissansen‐Totton, J., Wogan, N. F., Telus, M., & Fortney, J. J. (2022) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.2117933119 · Cited by 112
False Negatives for Remote Life Detection on Ocean-Bearing Planets: Lessons from the Early Earth
Reinhard, C. T., Olson, S. L., Schwieterman, E. W., & Lyons, T. W. (2017) · Astrobiology · doi:10.1089/ast.2016.1598 · Cited by 93
“, 2005) and has been previously used in spectral studies of the Archean Earth (Arney et al., 2016).”
BackgroundMethodSelf-citation
A Review of Possible Planetary Atmospheres in the TRAPPIST-1 System
Turbet, M., Bolmont, É., Bourrier, V., Demory, B.-O., Leconte, J., Owen, J. E., & Wolf, E. T. (2020) · Space Science Reviews · doi:10.1007/s11214-020-00719-1 · Cited by 92
“We do, however, acknowledge that the formation of high-altitude organic hazes from the NH3 and/or CH4 photolysis (Sagan and Chyba 1997; Wolf and Toon 2010; Arney et al. 2016) may shield these molecules.”
BackgroundSelf-citation
Biological regulation of atmospheric chemistry en route to planetary oxygenation
Izon, G., Zerkle, A. L., Williford, K. H., Farquhar, J., Poulton, S. W., & Claire, M. W. (2017) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1618798114 · Cited by 86
“, haze prevents methane photolysis), implicating intricate feedback systems between biological methane production, atmospheric chemistry, and surface-incident UV radiation (63).”
BackgroundMethodInfluentialSelf-citation
Exoplanet Classification and Yield Estimates for Direct Imaging Missions
Kopparapu, R. K., Hébrard, É., Belikov, R., Batalha, N. M., Mulders, G. D., Stark, C., Teal, D., Domagal-Goldman, S. D., & Mandell, A. M. (2018) · The Astrophysical Journal · doi:10.3847/1538-4357/aab205 · Cited by 88
“This process occurs on many solar system worlds (Courtin 2005; Waite et al. 2007; Gladstone et al. 2016), is thought to have occurred on Archean Earth (Arney et al. 2016), and likely occurs on exoplanets (Moses et al. 2011; Moses 2014).”
BackgroundSelf-citation
Organic Haze as a Biosignature in Anoxic Earth-like Atmospheres
Arney, G., Domagal-Goldman, S. D., & Meadows, V. (2017) · Astrobiology · doi:10.1089/ast.2017.1666 · Cited by 85
“Haze is included in SMART from Atmos via a particle binning scheme described in Arney et al. (2016).”
BackgroundMethodInfluentialSelf-citation
Photochemistry of Anoxic Abiotic Habitable Planet Atmospheres: Impact of New H 2 O Cross Sections
Ranjan, S., Schwieterman, E. W., Harman, C. E., Fateev, A., Sousa‐Silva, C., Seager, S., & Hu, R. (2020) · The Astrophysical Journal · doi:10.3847/1538-4357/ab9363 · Cited by 96
“To resolve this disagreement and derive a robust model for use in this work, we intercompare the models of Hu et al. (2012), Harman et al. (2015), and ATMOS (Arney et al. 2016, commit #be0de64; Archaean+haze template).”
BackgroundMethodInfluentialSelf-citation
Transient surface ocean oxygenation recorded in the ∼2.66-Ga Jeerinah Formation, Australia
Koehler, M. C., Buick, R., Kipp, M. A., Stüeken, E. E., & Zaloumis, J. (2018) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1720820115 · Cited by 72
“Alternatively, terrestrial cyanobacterial mat proliferation under a transient organic haze (18, 62, 63) providing temporary UV protection (64) may have increased the oxidative weathering flux of Se, but the feedback between O2 generation, aerobic methane oxidation, and haze formation needs to be explored in greater de…”
Background
A review of exoplanetary biosignatures
Grenfell, J. L. (2017) · Physics Reports · doi:10.1016/j.physrep.2017.08.003 · Cited by 74
Photochemical Haze Formation in the Atmospheres of Super-Earths and Mini-Neptunes
He, C., Hörst, S. M., Lewis, N. K., Yu, X., Moses, J. I., Kempton, E. M.-R., Marley, M. S., McGuiggan, P. M., Morley, C. V., Valenti, J. A., et al. (2018) · The Astronomical Journal · doi:10.3847/1538-3881/aac883 · Cited by 85
“As we discussed in our previous study (He et al. 2018), exoplanet atmospheric modelings used a broad size range of haze particles in the models: 5–10000 nm (see, e.g., Howe & Burrows 2012; Arney et al. 2016; Gao et al. 2017).”
Method
Exoplanet classification and yield estimates for direct imaging missions
(21879248), R. K., (21856967), E. H., Belikov, R., (7803182), N. B., (21879251), G. M., (15975902), C. S., (21879254), D. T., (21879257), S. D.-G., & (21840608), A. M. (2025) · Figshare · Cited by 76
Modeling p N 2 through Geological Time: Implications for Planetary Climates and Atmospheric Biosignatures
Stüeken, E. E., Kipp, M. A., Koehler, M. C., Schwieterman, E. W., Johnson, B., & Buick, R. (2016) · Astrobiology · doi:10.1089/ast.2016.1537 · Cited by 73
“, 2013) and characterize the surface temperature of a hypothetical Archean Earth with a global hydrocarbon haze (Arney et al., 2016).”
InfluentialSelf-citation
Exoplanet Biosignatures: At the Dawn of a New Era of Planetary Observations
Kiang, N. Y.-L., Domagal-Goldman, S. D., Parenteau, M. N., Catling, D. C., Fujii, Y., Meadows, V., Schwieterman, E. W., & Walker, S. I. (2018) · Astrobiology · doi:10.1089/ast.2018.1862 · Cited by 70
“Theoretical studies have identified potential atmospheric biosignatures for an anoxic planet, including an orange-hued organic haze (Arney et al., 2016) and ethane (C2H6; (Domagal-Goldman et al.”
BackgroundSelf-citation
Origin-of-life Molecules in the Atmosphere after Big Impacts on the Early Earth
Wogan, N. F., Catling, D. C., Zahnle, K. J., & Lupu, R. (2023) · The Planetary Science Journal · doi:10.3847/psj/aced83 · Cited by 81
Is the Faint Young Sun Problem for Earth Solved?
Charnay, B., Wolf, E. T., Marty, B. M., & Forget, F. (2020) · Space Science Reviews · doi:10.1007/s11214-020-00711-9 · Cited by 86
Self-citation
The Role of N 2 as a Geo-Biosignature for the Detection and Characterization of Earth-like Habitats
Lammer, H., Sproß, L., Grenfell, J. L., Scherf, M., Fossati, L., Lendl, M., & Cubillos, P. E. (2019) · Astrobiology · doi:10.1089/ast.2018.1914 · Cited by 67
“The possible detectability of an anoxic habitat, such as that of Earth during the Ar-chean with a CH 4 -rich atmosphere, is given by Arney et al. (2016) and Krissansen-Totton et al. (2018b).”
Laboratory Simulations of Haze Formation in the Atmospheres of Super-Earths and Mini-Neptunes: Particle Color and Size Distribution
He, C., Hörst, S. M., Lewis, N. K., Yu, X., Moses, J. I., Kempton, E. M.-R., McGuiggan, P. M., Morley, C. V., Valenti, J. A., & Vuitton, V. (2018) · The Astrophysical Journal Letters · doi:10.3847/2041-8213/aab42b · Cited by 69
“Currently, wide ranges of particle sizes, from 5 to 10,000 nm, are used in exoplanet atmospheric models (see, e.g., Howe & Burrows 2012; Arney et al. 2016; Gao et al. 2017).”
Method
Photochemical Haze Formation in the Atmospheres of Super-Earths and Mini-Neptunes
He, C., Moses, J. I., Kempton, E. M.-R., Valenti, J. A., Morley, C. V., Vuitton, V., Lewis, N. K., Marley, M. S., Hoerst, S. M., Yu, X., et al. (n.d.) · NASA STI Repository (National Aeronautics and Space Administration) · Cited by 71
Effects of primitive photosynthesis on Earth’s early climate system
Ozaki, K., Tajika, E., Hong, P. K., Nakagawa, Y., & Reinhard, C. T. (2018) · Nature Geoscience · doi:10.1038/s41561-017-0031-2 · Cited by 65
Abiotic O 2 Levels on Planets around F, G, K, and M Stars: Effects of Lightning-produced Catalysts in Eliminating Oxygen False Positives
Harman, C. E., Felton, R. C., Hu, R., Domagal-Goldman, S. D., Segura, A., Tian, F., & Kasting, J. F. (2018) · The Astrophysical Journal · doi:10.3847/1538-4357/aadd9b · Cited by 67
“The second model, Atmos, is described in detail in Arney et al. (2016), and while it shares its origins with the Harman et al. model, Zahnle (1986) began significant alterations.”
BackgroundSelf-citation
Large Interferometer For Exoplanets (LIFE)
Alei, E., Konrad, B. S., Angerhausen, D., Grenfell, J. L., Mollière, P., Quanz, S. P., Rugheimer, S., & Wunderlich, F. (2022) · Astronomy and Astrophysics · doi:10.1051/0004-6361/202243760 · Cited by 61
Venus, an Astrobiology Target
Limaye, S. S., Mogul, R., Baines, K. H., Bullock, M. A., Cockell, C. S., Cutts, J. A., Gentry, D. M., Grinspoon, D. H., Head, J. W., III, Jessup, K.-L., et al. (2021) · Astrobiology · doi:10.1089/ast.2020.2268 · Cited by 60
“Organic hazes with fractal shapes rather than spherical shaped particles have been suggested for Titan (Rannou et al. , 1997; Wolf and Toon, 2010) and primitive Earth (Arney et al. , 2016).”
Background
Colloquium: Physical constraints for the evolution of life on exoplanets
Lingam, M., & Loeb, A. (2019) · Reviews of Modern Physics · doi:10.1103/revmodphys.91.021002 · Cited by 63
Atmospheric Seasonality as an Exoplanet Biosignature
Olson, S. L., Schwieterman, E. W., Reinhard, C. T., Ridgwell, A. J., Kane, S. R., Meadows, V. S., & Lyons, T. W. (2018) · The Astrophysical Journal Letters · doi:10.3847/2041-8213/aac171 · Cited by 62
“We calculated seasonality in the O3 abundance arising from this O2 seasonality scenario using a 1D photochemical model (Kasting et al. 1979) that has a long legacy of modeling early Earth and Earth-like exoplanets (e.g., Arney et al. 2016, 2017).”
MethodSelf-citation
A Limited Habitable Zone for Complex Life
Schwieterman, E. W., Reinhard, C. T., Olson, S. L., Harman, C. E., & Lyons, T. W. (2019) · The Astrophysical Journal · doi:10.3847/1538-4357/ab1d52 · Cited by 62
“More recently, the code has been used to calculate photochemically self-consistent atmospheres for the Archean Earth and hazy planets orbiting other stars (Arney et al. 2016, 2017) and for calculating self-consistent trace gas abundances in the atmosphere of Proxima Centauri b (Meadows et al. 2018).”
MethodSelf-citation
Co-evolution of primitive methane-cycling ecosystems and early Earth’s atmosphere and climate
Sauterey, B., Charnay, B., Affholder, A., Mazevet, S., & Ferrière, R. (2020) · Nature Communications · doi:10.1038/s41467-020-16374-7 · Cited by 55
Self-citation
Transiting Exoplanet Atmospheres in the Era of JWST
Kempton, E. M.-R., & Knutson, H. A. (2024) · Reviews in Mineralogy and Geochemistry · doi:10.2138/rmg.2024.90.12 · Cited by 64
The future lifespan of Earth’s oxygenated atmosphere
Ozaki, K., & Reinhard, C. T. (2021) · Nature Geoscience · doi:10.1038/s41561-021-00693-5 · Cited by 56
A Methane Extension to the Classical Habitable Zone
Ramirez, R. M., & Kaltenegger, L. (2018) · The Astrophysical Journal · doi:10.3847/1538-4357/aab8fa · Cited by 60
“Even though the inner edge would be relatively robust to increases in CH4 at the concentrations considered, at even higher concentrations, the cooling effect from these hazes may be effective in moving the inner edge inward (e.g., Arney et al. 2016).”
Background
Haze evolution in temperate exoplanet atmospheres through surface energy measurements
Yu, X., He, C., Zhang, X., et al. (2021) · Nature Astronomy · doi:10.1038/s41550-021-01375-3 · Cited by 52
“tochemical hazes are signicant components in planetary and exoplanetary atmospheres [1, 2]. They could signicantly impact the radiation budget of planetary atmospheres, affecting planetary climates [3]. Recent work also suggests that hazes are the main particulate opacity sources in temperate exoplanetary atmospheres…”
Background
Sensitive probing of exoplanetary oxygen via mid-infrared collisional absorption
Fauchez, T. J., Villanueva, G. L., Schwieterman, E. W., Turbet, M., Arney, G., Pidhorodetska, D., Kopparapu, R. K., Mandell, A. M., & Domagal-Goldman, S. D. (2020) · Nature Astronomy · doi:10.1038/s41550-019-0977-7 · Cited by 56
Self-citation
Photochemical modelling of atmospheric oxygen levels confirms two stable states
Gregory, B. S., Claire, M. W., & Rugheimer, S. (2021) · Earth and Planetary Science Letters · doi:10.1016/j.epsl.2021.116818 · Cited by 50
Self-citation
Titan: Earth-like on the Outside, Ocean World on the Inside
MacKenzie, S., Birch, S., Hörst, S. M., Sotin, C., Barth, E. L., Lora, J. M., Trainer, M. G., Corlies, P., Malaska, M. J., Sciamma-O’Brien, E., et al. (2021) · The Planetary Science Journal · doi:10.3847/25c2cfeb.043eea88 · Cited by 57
Self-citation
Nitrogen Dioxide Pollution as a Signature of Extraterrestrial Technology
Kopparapu, R., Arney, G., Haqq-Misra, J., Lustig‐Yaeger, J., & Villanueva, G. (2021) · The Astrophysical Journal · doi:10.3847/1538-4357/abd7f7 · Cited by 56
Self-citation
A Catalog of Stellar Unified Properties (CATSUP) for 951 FGK-Stars within 30 pc
Hinkel, N., Mamajek, E., Turnbull, M., Osby, E., Shkolnik, E., Smith, G. H., Klimasewski, A., Somers, G., & Desch, S. (2017) · The Astrophysical Journal · doi:10.3847/1538-4357/aa8b0f · Cited by 37
“As the high energy UV photons alter the planets’ atmospheric evolution and photochemistry, interpretations of exoplanetary spectra are affected for both close-in giant planets and habitable zone earths (Miguel & Kaltenegger 2014; Rugheimer et al. 2015; Luger & Barnes 2015; Arney et al. 2016).”
Background
Possible link between Earth’s rotation rate and oxygenation
Klatt, J. M., Chennu, A., Arbic, B. K., Biddanda, B. A., & Dick, G. J. (2021) · Nature Geoscience · doi:10.1038/s41561-021-00784-3 · Cited by 51
Living at the Extremes: Extremophiles and the Limits of Life in a Planetary ContextPreprint
Merino, N., Aronson, H. S., Bojanova, D. P., et al. (2019) · doi:10.31223/osf.io/8eay6 · Cited by 49
Detectability of Molecular Signatures on TRAPPIST-1e through Transmission Spectroscopy Simulated for Future Space-based Observatories
Pidhorodetska, D., Fauchez, T. J., Villanueva, G. L., Domagal-Goldman, S. D., & Kopparapu, R. (2020) · The Astrophysical Journal Letters · doi:10.3847/2041-8213/aba4a1 · Cited by 48
“Software:Atmos (Arney et al. 2016), LMD-G (Wordsworth et al. 2011), PSG (Villanueva et al. 2018).”
BackgroundInfluentialSelf-citation
False Negatives for Remote Life Detection on Ocean-Bearing Planets: Lessons from the Early Earth.
Reinhard, C. T., Olson, S. L., Schwieterman, E. W., & Lyons, T. W. (2017) · eScholarship (California Digital Library) · Cited by 48
Self-citation
Factors Affecting Exoplanet Habitability
Meadows, V., & Barnes, R. (2018) · Springer eBooks · doi:10.1007/978-3-319-55333-7_57 · Cited by 52
Self-citation
Environmental control on microbial diversification and methane production in the Mesoarchean
Stüeken, E. E., & Buick, R. (2018) · Precambrian Research · doi:10.1016/j.precamres.2017.11.003 · Cited by 47
“As proposed by Arney et al. (2016), a haze could have facilitated the colonization of land masses, because it would have shielded organisms from harmful UV radiation.”
Background
Impact of space weather on climate and habitability of terrestrial-type exoplanets
Airapetian, V., Gopalswamy, N., Grenfell, J. L., Gronoff, G., Güdel, M., Herbst, K., Henning, W. G., Jackman, C. H., Jin, M., Johnstone, C. P., et al. (2020) · Yokohama National University Repository (Yokohama National University) · Cited by 41
TRAPPIST Habitable Atmosphere Intercomparison (THAI) Workshop Report
Fauchez, T. J., Turbet, M., Sergeev, D. E., Mayne, N. J., Spiga, A., Sohl, L. E., Saxena, P., Deitrick, R., Gilli, G., Domagal-Goldman, S. D., et al. (2021) · The Planetary Science Journal · doi:10.3847/psj/abf4df · Cited by 44
Self-citation
One-Pot Hydrogen Cyanide-Based Prebiotic Synthesis of Canonical Nucleobases and Glycine Initiated by High-Velocity Impacts on Early Earth
Ferus, M., Rimmer, P. B., Cassone, G., Knížek, A., Civiš, S., Šponer, J. E., Ivanek, O., Šponer, J., Saeidfirozeh, H., Kubelík, P., et al. (2020) · Astrobiology · doi:10.1089/ast.2020.2231 · Cited by 47
“In the simulated impact, formation of important molecules is followed by one-pot synthesis of prebiotic compounds at moderate temperatures combined with spontaneous chemistry after cooling down the system. hazes shielded the surface of the early Earth is explored in Arney et al. (2016).”
AU Microscopii in the Far-UV: Observations in Quiescence, during Flares, and Implications for AU Mic b and c
Feinstein, A. D., France, K. C., Youngblood, A. A., Duvvuri, G. M., Teal, D. J., Cauley, P. W., Seligman, D. Z., Gaidos, E. J., Kempton, E. M.-R., Bean, J. L., et al. (2022) · The Astronomical Journal · doi:10.3847/1538-3881/ac8107 · Cited by 46
“This updated version includes the addition of reactions for nitrogen-bearing species and the hydrocarbon haze prescription from Arney et al. (2016, 2017).”
Background
3D modelling of the impact of stellar activity on tidally locked terrestrial exoplanets: atmospheric composition and habitability
Ridgway, R. J., Zamyatina, M., Mayne, N. J., Manners, J. C., Lambert, F. H., Braam, M., Drummond, B., Hébrard, É., Palmer, P. I., & Kohary, K. I. (2022) · Monthly Notices of the Royal Astronomical Society · doi:10.1093/mnras/stac3105 · Cited by 44
Distinguishing between Wet and Dry Atmospheres of TRAPPIST-1 e and f
Wunderlich, F., Scheucher, M., Godolt, M., Grenfell, J. L., Schreier, F., Schneider, P. C., Wilson, D. J., Sánchez-López, A., López‐Puertas, M., & Rauer, H. (2020) · The Astrophysical Journal · doi:10.3847/1538-4357/aba59c · Cited by 52
“To reproduce an O2 mixing ratio of 0.21 for our Earth validation run (in Section 2.4.1), we need to set a νdep of 2×10 −8cms−1 (not shown), which is similar to the O2νdep=1× 10 −8cms−1 used by Arney et al. (2016).”
MethodInfluential
Detectability of Molecular Signatures on TRAPPIST-1e through Transmission Spectroscopy Simulated for Future Space-based Observatories
Pidhorodetska, D., Fauchez, T. J., Villanueva, G. L., Domagal-Goldman, S. D., & Kopparapu, R. (2020) · Maryland Shared Open Access Repository (USMAI Consortium) · doi:10.13016/m2mmhx-mukf · Cited by 43
Self-citation
Phosphine as a Biosignature Gas in Exoplanet Atmospheres
Sousa‐Silva, C., Seager, S., Ranjan, S., Petkowski, J. J., Zhan, Z., Hu, R., & Bains, W. (2019) · DSpace@MIT (Massachusetts Institute of Technology) · Cited by 41
Impact of photochemical hazes and gases on exoplanet atmospheric thermal structure
Lavvas, P., & Arfaux, A. (2021) · Monthly Notices of the Royal Astronomical Society · doi:10.1093/mnras/stab456 · Cited by 43
The K Dwarf Advantage for Biosignatures on Directly Imaged Exoplanets
Arney, G. (2019) · The Astrophysical Journal Letters · doi:10.3847/2041-8213/ab0651 · Cited by 50
“To simulate our atmospheres, we use a coupled 1D photochemical-climate model called Atmos, which is described in Arney et al. (2016).”
MethodInfluentialSelf-citation
Rethinking CO Antibiosignatures in the Search for Life Beyond the Solar System
Schwieterman, E. W., Reinhard, C. T., Olson, S. L., Ozaki, K., Harman, C. E., Hong, P. K., & Lyons, T. W. (2019) · The Astrophysical Journal · doi:10.3847/1538-4357/ab05e1 · Cited by 49
“For our “anoxic” scenarios we adopt boundary conditions consistent with an Archean Earth with 2% CO2 and thin or no haze 12 https://github.com/VirtualPlanetaryLaboratory/atmos (Arney et al. 2016, 2017).”
MethodSelf-citation
Timescales for Prebiotic Photochemistry Under Realistic Surface Ultraviolet Conditions
Rimmer, P. B., Thompson, S. J., Xu, J., Russell, D. A., Green, N. J., Ritson, D. J., Sutherland, J. D., & Queloz, D. P. (2021) · Astrobiology · doi:10.1089/ast.2020.2335 · Cited by 43
“It may have been more reducing, and if so, there would likely have been thick photochemical hazes that can obscure the UV light between 200 and 300 nm (Arney et al., 2016).”
Background
Atmospheric CO 2 levels from 2.7 billion years ago inferred from micrometeorite oxidation
Lehmer, O. R., Catling, D. C., Buick, R., Brownlee, D. E., & Newport, S. (2020) · Science Advances · doi:10.1126/sciadv.aay4644 · Cited by 39
Biosignature Anisotropy Modeled on Temperate Tidally Locked M-dwarf Planets
Chen, H., Wolf, E. T., Kopparapu, R., Domagal-Goldman, S. D., & Horton, D. E. (2018) · The Astrophysical Journal Letters · doi:10.3847/2041-8213/aaedb2 · Cited by 43
“…for example on anoxic Archean Earth (∼3.0 Ga), hydrocarbons and organosulfur biosignatures (C2H6, CH4, OCS, DMS etc.) could rise to more prominent abundances and hence may be conducive to remote detection (HaqqMisra et al. 2008; Domagal-Goldman et al. 2011; Hu et al. 2012; Arney et al. 2016).”
BackgroundInfluentialSelf-citation
Mission to Planet Earth: The First Two Billion Years
Stüeken, E. E., Som, S. M., Claire, M. W., Rugheimer, S., Scherf, M., Sproß, L., Tosi, N., Ueno, Y., & Lammer, H. (2020) · Space Science Reviews · doi:10.1007/s11214-020-00652-3 · Cited by 39
Self-citation
Chemical conditions on Hycean worlds
Madhusudhan, N., Moses, J. I., Rigby, F., & Barrier, E. (2023) · Faraday Discussions · doi:10.1039/d3fd00075c · Cited by 42
Haze evolution in temperate exoplanet atmospheres through surface energy measurements
Yu, X., He, C., Zhang, X., et al. (2021) · eScholarship (California Digital Library) · Cited by 38
Effects of UV Stellar Spectral Uncertainty on the Chemistry of Terrestrial Atmospheres
Teal, D. J., Kempton, E. M.-R., Bastelberger, S., Youngblood, A. A., & Arney, G. (2022) · The Astrophysical Journal · doi:10.3847/1538-4357/ac4d99 · Cited by 38
“These atmospheres have far more photochemically active species and the potential for strong radiative feedback from haze formation (Arney et al. 2016).”
BackgroundMethodInfluentialSelf-citation
When is Chemical Disequilibrium in Earth-like Planetary Atmospheres a Biosignature versus an Anti-biosignature? Disequilibria from Dead to Living Worlds
Wogan, N. F., & Catling, D. C. (2020) · The Astrophysical Journal · doi:10.3847/1538-4357/ab7b81 · Cited by 40
“…the Kasting group (Pavlov et al. 2001), and versions of this code have been used to simulate the Archean and Proterozoic Earth atmosphere (Zahnle et al. 2006), Mars (Zahnle et al. 2008; Smith et al. 2014; Sholes et al. 2019), and exoplanet atmospheres (Arney et al. 2016; Schwieterman et al. 2019).”
Method
The First Habitable-zone Earth-sized Planet from TESS. III. Climate States and Characterization Prospects for TOI-700 d
Suissa, G., Wolf, E. T., Kopparapu, R., Villanueva, G. L., Fauchez, T. J., Mandell, A. M., Arney, G., Gilbert, E. A., Schlieder, J. E., Barclay, T., et al. (2020) · The Astronomical Journal · doi:10.3847/1538-3881/aba4b4 · Cited by 48
“Oxygen radicals generated by this photolysis are the dominant sink of CH4 in modern Earth’s atmosphere; with the decrease of this photolysis rate comes the potential increase in CH4 abundance for planets around M dwarfs.”
BackgroundInfluentialSelf-citation
Is ozone a reliable proxy for molecular oxygen?
Kozakis, T., Mendonça, J. M., & Buchhave, L. A. (2022) · Astronomy and Astrophysics · doi:10.1051/0004-6361/202244164 · Cited by 44
The Fundamental Connections between the Solar System and Exoplanetary Science
Kane, S. R., Arney, G., Byrne, P. K., Dalba, P. A., Desch, S. J., Horner, J., Izenberg, N. R., Mandt, K. E., Meadows, V. S., & Quick, L. C. (2021) · Journal of Geophysical Research Planets · doi:10.1029/2020je006643 · Cited by 41
Self-citation
Near-infrared transmission spectrum of TRAPPIST-1 h usingHubbleWFC3 G141 observations
Gressier, A., Mori, M., Changeat, Q., Edwards, B., Beaulieu, J., Marcq, E., & Charnay, B. (2021) · Astronomy and Astrophysics · doi:10.1051/0004-6361/202142140 · Cited by 34
Self-citation
Identifiable acetylene features predicted for young Earth-like exoplanets with reducing atmospheres undergoing heavy bombardment
Rimmer, P. B., Ferus, M., Waldmann, I. P., Knížek, A., Kalvaitis, D., Ivanek, O., Kubelík, P., Yurchenko, S. N., Burian, T., Dostál, J., et al. (2020) · The Astrophysical Journal · doi:10.3847/1538-4357/ab55e8 · Cited by 34
“This is consistent with experimental and other model results for gases with high concentrations of CH4 (Trainer et al. 2004, 2006; Arney et al. 2016), and that CO changes the character of the resulting haze (Hörst & Tolbert 2014).”
BackgroundResultInfluential
Impact of the Dimethyl Sulfoxide Reductase Superfamily on the Evolution of Biogeochemical Cycles
Wells, M., Kim, M., Akob, D. M., Basu, P., & Stolz, J. F. (2023) · Microbiology Spectrum · doi:10.1128/spectrum.04145-22 · Cited by 33
HAZMAT. II. Ultraviolet Variability of Low-mass Stars in the GALEX Archive
Miles, B., & Shkolnik, E. L. (2017) · The Astronomical Journal · doi:10.3847/1538-3881/aa71ab · Cited by 33
Rethinking CO Antibiosignatures in the Search for Life Beyond the Solar System
Schwieterman, E. W., Reinhard, C. T., Olson, S. L., Ozaki, K., Harman, C. E., Hong, P. K., & Lyons, T. W. (2019) · NASA STI Repository (National Aeronautics and Space Administration) · doi:10.6082/87s5e-7ar65 · Cited by 32
Self-citation
Life as the Only Reason for the Existence of N2–O2-Dominated Atmospheres
Sproß, L., Scherf, M., Shematovich, V. I., Bisikalo, D. V., & Lammer, H. (2021) · Astronomy Reports · doi:10.1134/s1063772921040077 · Cited by 33
Detecting the proposed CH4–CO2 biosignature pair with the James Webb Space Telescope: TRAPPIST-1e and the effect of cloud/haze
Evans, T. M. (2021) · Monthly Notices of the Royal Astronomical Society · doi:10.1093/mnras/stab3383 · Cited by 32

Authors: Arney, G., Domagal-Goldman, S. D., Meadows, V. S., Wolf, E. T., Schwieterman, E., Charnay, B., Claire, M., Hébrard, E., & Trainer, M. G.
Affiliations: Goddard Space Flight Center (US)
University of Washington (US)
University of Colorado Boulder (US)
University of California, Riverside (US)
University of St Andrews (GB)
NASA Goddard Space Flight Center
Corresponding author: Arney, Giada
ORCID: Charnay, Benjamin
Venue: Astrobiology
Publisher: SAGE Publications
Published: 2016-11
Volume: 16
Issue: 11
Pages: 873-899
ISSN: 1531-1074 (ISSN-L)
1557-8070
DOI: 10.1089/ast.2015.1422
PMC: PMC5148108
OpenAlex: W2534050968
Semantic Scholar: 62da501fd3e70b940830188582e2e383e75193d3
Cited by: 327
References: 136
Citations by year: 2026: 22 · 2025: 59 · 2024: 28 · 2023: 33 · 2022: 33 · 2021: 30 · 2020: 33 · 2019: 25 · 2018: 45 · 2017: 18 · 2016: 1
FWCI: 14.17
Type: journal article
Language: en
Open access: hybrid
doi.org
Licence: cc-by-nc
creativecommons.org/licenses/by-nc/4.0/ (vor)
journals.sagepub.com/page/policies/text-and-data-mining-license (tdm)
Locations: Astrobiology (publishedVersion, cc-by-nc)
PubMed Central (publishedVersion, cc-by-nc)
PubMed (publishedVersion)
Open Research Exeter (University of Exeter) (acceptedVersion)
arXiv (Cornell University) (submittedVersion)
HAL (submittedVersion)
eScholarship (California Digital Library) (submittedVersion, cc-by-nc)
St Andrews Research Repository (St Andrews Research Repository) (submittedVersion, cc-by-nc)
arXiv (Cornell University)
Funders: Natural Environment Research Council (NE/J022802/2)
Topics: Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Space Science and Extraterrestrial Life
Physical Sciences › Earth and Planetary Sciences › Space and Planetary Science › Astro and Planetary Science
Physical Sciences › Earth and Planetary Sciences › Space and Planetary Science › Planetary Science and Exploration
Keywords: Archean, atmospheric haze, habitability, faint young Sun, UV protection, biosignatures, methane, self-shielding, exoplanet atmospheres, surface cooling
MeSH terms: Atmosphere, Climate, Extraterrestrial Environment, Gases, Models, Theoretical, Particle Size, Spectrophotometry, Ultraviolet, Temperature, Ultraviolet Rays, Water, Earth, Planet, Exobiology

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

A language model drew the claims from the paper on 2026-10-08, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).

A second model labelled each claim on 2026-10-08 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review

The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth

Abstract

Overview

AI snapshot

TL;DR

Key findings

Methods

Limitations

Integrity signals

Verification

Claims the paper makes

Claims other papers make about this one

Self-check

Citations

Cites

Cited by

Metadata

Record

About these checks