Redfield revisited: 2. What regulates the oxygen content of the atmosphere?

Lenton, Timothy M.; Watson, Andrew

doi:10.1029/1999gb900076

Cited by 154 publications

(150 citation statements)

References 81 publications

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“…The P weathering flux is partly tied to bulk silicate weathering, for example, due to the dissolution of apatite inclusions in silicate rocks, and the silicate weathering flux of alkalinity is in turn set by negative feedback in the longterm carbon cycle, so is ultimately controlled by the degassing input of CO 2 on timescales ≥1 My (7,10). However, plants and their associated mycorrhizal fungi can increase phosphorus weathering (20)(21)(22), and this could be sustained on longer timescales if they preferentially weather phosphorus relative to alkalinity.…”

Section: Significancementioning

confidence: 99%

Earliest land plants created modern levels of atmospheric oxygen

Lenton

Dahl

Daines

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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274

224

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The progressive oxygenation of the Earth's atmosphere was pivotal to the evolution of life, but the puzzle of when and how atmospheric oxygen (O 2 ) first approached modern levels (∼21%) remains unresolved. Redox proxy data indicate the deep oceans were oxygenated during 435-392 Ma, and the appearance of fossil charcoal indicates O 2 >15-17% by 420-400 Ma. However, existing models have failed to predict oxygenation at this time. Here we show that the earliest plants, which colonized the land surface from ∼470 Ma onward, were responsible for this mid-Paleozoic oxygenation event, through greatly increasing global organic carbon burialthe net long-term source of O 2 . We use a trait-based ecophysiological model to predict that cryptogamic vegetation cover could have achieved ∼30% of today's global terrestrial net primary productivity by ∼445 Ma. Data from modern bryophytes suggests this plentiful early plant material had a much higher molar C:P ratio (∼2,000) than marine biomass (∼100), such that a given weathering flux of phosphorus could support more organic carbon burial. Furthermore, recent experiments suggest that early plants selectively increased the flux of phosphorus (relative to alkalinity) weathered from rocks. Combining these effects in a model of long-term biogeochemical cycling, we reproduce a sustained +2‰ increase in the carbonate carbon isotope (δ 13 C) record by ∼445 Ma, and predict a corresponding rise in O 2 to present levels by 420-400 Ma, consistent with geochemical data. This oxygen rise represents a permanent shift in regulatory regime to one where fire-mediated negative feedbacks stabilize high O 2 levels.oxygen | Paleozoic | phosphorus | plants | weathering

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Section: Significancementioning

confidence: 99%

Earliest land plants created modern levels of atmospheric oxygen

Lenton

Dahl

Daines

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

274

224

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“…A. Raven et al 497 Phosphorus is one of the biogeochemical regulators of the O 2 content of the atmosphere [96,97]. This topic will be returned to below in the context of ocean deoxygenation as a function of increases in CO 2 and temperature.…”

Section: Oxygen Accumulation Rubisco Oxygenase and The Metabolism Ofmentioning

confidence: 99%

“…This nitrification-denitrification sequence decreases the availability of combined nitrogen to non-diazotrophic primary producers. In the case of phosphorus, the availability of O 2 converts Fe(II) to oxidized iron (Fe(III), which binds phosphate and thus decreases global phosphorus availability [96,97].…”

Section: Oxygen Accumulation Rubisco Oxygenase and The Metabolism Ofmentioning

confidence: 99%

Algal evolution in relation to atmospheric CO ₂ : carboxylases, carbon-concentrating mechanisms and carbon oxidation cycles

Raven

Giordano

Beardall

et al. 2012

Phil. Trans. R. Soc. B

251

209

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Oxygenic photosynthesis evolved at least 2.4 Ga; all oxygenic organisms use the ribulose bisphosphate carboxylase-oxygenase (Rubisco) -photosynthetic carbon reduction cycle (PCRC) rather than one of the five other known pathways of autotrophic CO 2 assimilation. The high CO 2 and (initially) O 2 -free conditions permitted the use of a Rubisco with a high maximum specific reaction rate. As CO 2 decreased and O 2 increased, Rubisco oxygenase activity increased and 2-phosphoglycolate was produced, with the evolution of pathways recycling this inhibitory product to sugar phosphates. Changed atmospheric composition also selected for Rubiscos with higher CO 2 affinity and CO 2 /O 2 selectivity correlated with decreased CO 2 -saturated catalytic capacity and/or for CO 2 -concentrating mechanisms (CCMs). These changes increase the energy, nitrogen, phosphorus, iron, zinc and manganese cost of producing and operating Rubisco -PCRC, while biosphere oxygenation decreased the availability of nitrogen, phosphorus and iron. The majority of algae today have CCMs; the timing of their origins is unclear. If CCMs evolved in a low-CO 2 episode followed by one or more lengthy high-CO 2 episodes, CCM retention could involve a combination of environmental factors known to favour CCM retention in extant organisms that also occur in a warmer high-CO 2 ocean. More investigations, including studies of genetic adaptation, are needed.

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“…Vegetation, wildfire and atmospheric oxygen on Earth have changed throughout geological times (Lovelock, 1979;Lenton and Watson, 2000), and are dependent on each other, determining the evolution of ecosystems, the carbon cycle, and the climate, as found in the fossil record (Belcher and McElwain, 2008;Belcher et al, 2010;Lenton, 2013). Increasing the oxygen concentration (X O 2 , percentage by volume) above the present-day level of 21%, the ignition probability of vegetation on land increases (Lovelock and Lodge, 1972;Lenton and Watson, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…Increasing the oxygen concentration (X O 2 , percentage by volume) above the present-day level of 21%, the ignition probability of vegetation on land increases (Lovelock and Lodge, 1972;Lenton and Watson, 2000). The influence of atmospheric oxygen on the flammability of Earth ecosystems has been investigated in Wildman et al (2004); Belcher and McElwain (2008) ;Belcher et al (2010); Watson and Lovelock (2013).…”

Section: Introductionmentioning

confidence: 99%

Interactions of Earth's atmospheric oxygen and fuel moisture in smouldering wildfires

Huang

Rein

2016

Science of The Total Environment

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Vegetation, wildfire and atmospheric oxygen on Earth have changed throughout geological times, and are dependent on each other, determining the evolution of ecosystems, the carbon cycle, and the climate, as found in the fossil record. Previous work in the literature has only studied flaming wildfires, but smouldering is the most persistent type of fire phenomena, consuming large amounts of biomass. In this study, the dependence of smouldering fires in peatlands, the largest wildfires on Earth, with atmospheric oxygen is investigated. A physics-based computational model of reactive porous media is developed which was previously validated against experiments. Simulations are conducted for wide ranges of atmospheric oxygen concentrations and fuel moisture contents to find thresholds for ignition and extinction. Results show that the predicted rate of spread increases in oxygen-rich atmospheres, while it decreases over wetter fuels. A novel nonlinear relationship between critical oxygen and critical moisture is found. More importantly, we show that compared to previous work on flaming fires, smouldering fires can be ignited and sustained at a substantially higher moisture content (> 100%), and at a substantially lower oxygen concentration (∼ 12%). This defines a possible lower oxygen threshold for wildfire and could help interpret the char remains and paleo fire activities seen in the fossil record.

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Redfield revisited: 2. What regulates the oxygen content of the atmosphere?

Cited by 154 publications

References 81 publications

Earliest land plants created modern levels of atmospheric oxygen

Earliest land plants created modern levels of atmospheric oxygen

Algal evolution in relation to atmospheric CO ₂ : carboxylases, carbon-concentrating mechanisms and carbon oxidation cycles

Interactions of Earth's atmospheric oxygen and fuel moisture in smouldering wildfires

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Redfield revisited: 2. What regulates the oxygen content of the atmosphere?

Cited by 154 publications

References 81 publications

Earliest land plants created modern levels of atmospheric oxygen

Earliest land plants created modern levels of atmospheric oxygen

Algal evolution in relation to atmospheric CO 2 : carboxylases, carbon-concentrating mechanisms and carbon oxidation cycles

Interactions of Earth's atmospheric oxygen and fuel moisture in smouldering wildfires

Contact Info

Product

Resources

About

Algal evolution in relation to atmospheric CO ₂ : carboxylases, carbon-concentrating mechanisms and carbon oxidation cycles