The lungs of the Earth: Review of the carbon cycle and mass extinction of species

Abstract. The vehicles that fly the satellite into a model of the Earth system are observation operators. They provide the link between the quantities simulated by the model and the quantities observed from space, either directly (spectral radiance) or indirectly estimated through a retrieval scheme (biogeophysical variables). By doing so, observation operators enable modellers to properly compare, evaluate, and constrain their models with the model analogue of the satellite observations. This paper provides the formalism and a few examples of how observation operators can be used in combination with data assimilation techniques to better ingest satellite products in a manner consistent with the dynamics of the Earth system expressed by models. It describes commonalities and potential synergies between assimilation and classical retrievals. This paper explains how the combination of observation operators and their derivatives (linearizations) form powerful research tools. It introduces a technique called automatic differentiation that greatly simplifies both the development and the maintenance of code for the evaluation of derivatives. Throughout this paper, a special focus lies on applications to the carbon cycle.

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Introduction

The Phanerozoic Carbon Cycle ◽

10.1093/oso/9780195173338.003.0003 ◽

2004 ◽

Author(s):

Robert A. Berner

Keyword(s):

Climate Change ◽

Carbon Dioxide ◽

Carbon Cycle ◽

Global Climate ◽

Geological Time ◽

Short Term ◽

Quaternary Period ◽

Geological Time Scale ◽

The Earth

The cycle of carbon is essential to the maintenance of life, to climate, and to the composition of the atmosphere and oceans. What is normally thought of as the “carbon cycle” is the transfer of carbon between the atmosphere, the oceans, and life. This is not the subject of interest of this book. To understand this apparently confusing statement, it is necessary to separate the carbon cycle into two cycles: the short-term cycle and the long-term cycle. The “carbon cycle,” as most people understand it, is represented in figure 1.1. Carbon dioxide is taken up via photosynthesis by green plants on the continents or phytoplankton in the ocean. On land carbon is transferred to soils by the dropping of leaves, root growth, and respiration, the death of plants, and the development of soil biota. Land herbivores eat the plants, and carnivores eat the herbivores. In the oceans the phytoplankton are eaten by zooplankton that are in turn eaten by larger and larger organisms. The plants, plankton, and animals respire CO2. Upon death the plants and animals are decomposed by microorganisms with the ultimate production of CO2. Carbon dioxide is exchanged between the oceans and atmosphere, and dissolved organic matter is carried in solution by rivers from soils to the sea. This all constitutes the shortterm carbon cycle. The word “short-term” is used because the characteristic times for transferring carbon between reservoirs range from days to tens of thousands of years. Because the earth is more than four billion years old, this is short on a geological time scale. As the short-term cycle proceeds, concentrations of the two principal atmospheric gases, CO2 and CH4, can change as a result of perturbations of the cycle. Because these two are both greenhouse gases—in other words, they adsorb outgoing infrared radiation from the earth surface—changes in their concentrations can involve global warming and cooling over centuries and many millennia. Such changes have accompanied global climate change over the Quaternary period (past 2 million years), although other factors, such as variations in the receipt of solar radiation due to changes in characteristics of the earth’s orbit, have also contributed to climate change.

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The Archean atmosphere

Science Advances ◽

10.1126/sciadv.aax1420 ◽

2020 ◽

Vol 6 (9) ◽

pp. eaax1420 ◽

Cited By ~ 30

Author(s):

David C. Catling ◽

Kevin J. Zahnle

Keyword(s):

Carbon Cycle ◽

Greenhouse Gas ◽

Solid Earth ◽

Atmospheric Composition ◽

Detailed Understanding ◽

Average Surface ◽

Substantial Loss ◽

Mass Fractionation ◽

The Earth ◽

Surface Temperatures

The atmosphere of the Archean eon—one-third of Earth’s history—is important for understanding the evolution of our planet and Earth-like exoplanets. New geological proxies combined with models constrain atmospheric composition. They imply surface O2 levels <10−6 times present, N2 levels that were similar to today or possibly a few times lower, and CO2 and CH4 levels ranging ~10 to 2500 and 102 to 104 times modern amounts, respectively. The greenhouse gas concentrations were sufficient to offset a fainter Sun. Climate moderation by the carbon cycle suggests average surface temperatures between 0° and 40°C, consistent with occasional glaciations. Isotopic mass fractionation of atmospheric xenon through the Archean until atmospheric oxygenation is best explained by drag of xenon ions by hydrogen escaping rapidly into space. These data imply that substantial loss of hydrogen oxidized the Earth. Despite these advances, detailed understanding of the coevolving solid Earth, biosphere, and atmosphere remains elusive, however.

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Rapid ocean acidification and protracted Earth system recovery followed the end-Cretaceous Chicxulub impact

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1905989116 ◽

2019 ◽

Vol 116 (45) ◽

pp. 22500-22504 ◽

Cited By ~ 25

Author(s):

Michael J. Henehan ◽

Andy Ridgwell ◽

Ellen Thomas ◽

Shuang Zhang ◽

Laia Alegret ◽

...

Keyword(s):

Carbon Cycle ◽

Ocean Acidification ◽

Carbon Isotope ◽

Primary Productivity ◽

Deep Sea ◽

Mass Extinction ◽

System Modeling ◽

Earth System ◽

Ph Gradients ◽

Chicxulub Impact

Mass extinction at the Cretaceous–Paleogene (K-Pg) boundary coincides with the Chicxulub bolide impact and also falls within the broader time frame of Deccan trap emplacement. Critically, though, empirical evidence as to how either of these factors could have driven observed extinction patterns and carbon cycle perturbations is still lacking. Here, using boron isotopes in foraminifera, we document a geologically rapid surface-ocean pH drop following the Chicxulub impact, supporting impact-induced ocean acidification as a mechanism for ecological collapse in the marine realm. Subsequently, surface water pH rebounded sharply with the extinction of marine calcifiers and the associated imbalance in the global carbon cycle. Our reconstructed water-column pH gradients, combined with Earth system modeling, indicate that a partial ∼50% reduction in global marine primary productivity is sufficient to explain observed marine carbon isotope patterns at the K-Pg, due to the underlying action of the solubility pump. While primary productivity recovered within a few tens of thousands of years, inefficiency in carbon export to the deep sea lasted much longer. This phased recovery scenario reconciles competing hypotheses previously put forward to explain the K-Pg carbon isotope records, and explains both spatially variable patterns of change in marine productivity across the event and a lack of extinction at the deep sea floor. In sum, we provide insights into the drivers of the last mass extinction, the recovery of marine carbon cycling in a postextinction world, and the way in which marine life imprints its isotopic signal onto the geological record.

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A new Rhaetian δ13Corg record: Carbon cycle disturbances, volcanism, End-Triassic mass Extinction (ETE)

Earth-Science Reviews ◽

10.1016/j.earscirev.2018.01.004 ◽

2018 ◽

Vol 178 ◽

pp. 92-104 ◽

Cited By ~ 8

Author(s):

Mariachiara Zaffani ◽

Flavio Jadoul ◽

Manuel Rigo

Keyword(s):

Carbon Cycle ◽

Mass Extinction

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Analytically tractable climate-carbon cycle feedbacks under 21st century anthropogenic forcing

10.5194/esd-2017-78 ◽

2017 ◽

Author(s):

Steven J. Lade ◽

Jonathan F. Donges ◽

Ingo Fetzer ◽

John M. Anderies ◽

Christian Beer ◽

...

Keyword(s):

Carbon Cycle ◽

Model Test ◽

Global Climate ◽

Earth System ◽

Planetary Boundaries ◽

Cycle Model ◽

Carbon Cycle Model ◽

The Earth ◽

Analytical Expressions ◽

Earth System Models

Abstract. Changes to climate-carbon cycle feedbacks may significantly affect the Earth System’s response to greenhouse gas emissions. These feedbacks are usually analysed from numerical output of complex and arguably opaque Earth System Models (ESMs). Here, we construct a stylized global climate-carbon cycle model, test its output against complex ESMs, and investigate the strengths of its climate-carbon cycle feedbacks analytically. The analytical expressions we obtain aid understanding of carbon-cycle feedbacks and the operation of the carbon cycle. We use our results to analytically study the relative strengths of different climate-carbon cycle feedbacks and how they may change in the future, as well as to compare different feedback formalisms. Simple models such as that developed here also provide workbenches for simple but mechanistically based explorations of Earth system processes, such as interactions and feedbacks between the Planetary Boundaries, that are currently too uncertain to be included in complex ESMs.

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Characteristic disruptions of an excitable carbon cycle

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1905164116 ◽

2019 ◽

Vol 116 (30) ◽

pp. 14813-14822 ◽

Cited By ~ 5

Author(s):

Daniel H. Rothman

Keyword(s):

Mathematical Model ◽

Carbon Cycle ◽

Mass Extinction ◽

Rate Of Change ◽

Stable Steady State ◽

Mass Extinctions ◽

Carbon Mass ◽

History Of ◽

External Sources ◽

Major Disruption

The history of the carbon cycle is punctuated by enigmatic transient changes in the ocean’s store of carbon. Mass extinction is always accompanied by such a disruption, but most disruptions are relatively benign. The less calamitous group exhibits a characteristic rate of change whereas greater surges accompany mass extinctions. To better understand these observations, I formulate and analyze a mathematical model that suggests that disruptions are initiated by perturbation of a permanently stable steady state beyond a threshold. The ensuing excitation exhibits the characteristic surge of real disruptions. In this view, the magnitude and timescale of the disruption are properties of the carbon cycle itself rather than its perturbation. Surges associated with mass extinction, however, require additional inputs from external sources such as massive volcanism. Surges are excited when CO2 enters the oceans at a flux that exceeds a threshold. The threshold depends on the duration of the injection. For injections lasting a time ti≳10,000 y in the modern carbon cycle, the threshold flux is constant; for smaller ti, the threshold scales like ti−1. Consequently the unusually strong but geologically brief duration of modern anthropogenic oceanic CO2 uptake is roughly equivalent, in terms of its potential to excite a major disruption, to relatively weak but longer-lived perturbations associated with massive volcanism in the geologic past.

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Dust Constraints from joint Observational-Modelling-experiMental analysis (DustCOMM): comparison with measurements and model simulations

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-829-2020 ◽

2020 ◽

Vol 20 (2) ◽

pp. 829-863 ◽

Cited By ~ 2

Author(s):

Adeyemi A. Adebiyi ◽

Jasper F. Kok ◽

Yang Wang ◽

Akinori Ito ◽

David A. Ridley ◽

...

Keyword(s):

Mass Extinction ◽

Global Model ◽

Earth System ◽

Atmospheric Dust ◽

Global Models ◽

Model Simulations ◽

Extinction Efficiency ◽

Dust Size Distribution ◽

The Earth ◽

Mass Extinction Efficiency

Abstract. Mineral dust is the most abundant aerosol species by mass in the atmosphere, and it impacts global climate, biogeochemistry, and human health. Understanding these varied impacts on the Earth system requires accurate knowledge of dust abundance, size, and optical properties, and how they vary in space and time. However, current global models show substantial biases against measurements of these dust properties. For instance, recent studies suggest that atmospheric dust is substantially coarser and more aspherical than accounted for in models, leading to persistent biases in modelled impacts of dust on the Earth system. Here, we facilitate more accurate constraints on dust impacts by developing a new dataset: Dust Constraints from joint Observational-Modelling-experiMental analysis (DustCOMM). This dataset combines an ensemble of global model simulations with observational and experimental constraints on dust size distribution and shape to obtain more accurate constraints on three-dimensional (3-D) atmospheric dust properties than is possible from global model simulations alone. Specifically, we present annual and seasonal climatologies of the 3-D dust size distribution, 3-D dust mass extinction efficiency at 550 nm, and two-dimensional (2-D) atmospheric dust loading. Comparisons with independent measurements taken over several locations, heights, and seasons show that DustCOMM estimates consistently outperform conventional global model simulations. In particular, DustCOMM achieves a substantial reduction in the bias relative to measured dust size distributions in the 0.5–20 µm diameter range. Furthermore, DustCOMM reproduces measurements of dust mass extinction efficiency to almost within the experimental uncertainties, whereas global models generally overestimate the mass extinction efficiency. DustCOMM thus provides more accurate constraints on 3-D dust properties, and as such can be used to improve global models or serve as an alternative to global model simulations in constraining dust impacts on the Earth system.

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Investigation of the Roadside Forest Based on "Carbon Neutral"

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.779-780.1314 ◽

2013 ◽

Vol 779-780 ◽

pp. 1314-1319

Author(s):

Xing Long Zhu ◽

Chen Zhao

Keyword(s):

Carbon Sequestration ◽

Carbon Cycle ◽

Transport System ◽

Carbon Balance ◽

Carbon Emission ◽

Carbon Sink ◽

The Road ◽

The Earth ◽

Carbon Neutral ◽

Highway System

The paper discusses the importance of increasing the carbon sink function of the highway system in maintaining carbon cycle balance of the Earth and "Carbon neutral" concept is used in highway roadside design. The carbon emission and carbon sequestration capacity of forest on both sides of the highway system are also calculated. The results show that most of the road green design has not yet reached a self-balancing capability of neutral carbon sink, and the establishment of the carbon sink forest from 50m to 100m will realize the carbon balance of the transport system.

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Has the Earth been exposed to numerous supernovae within the last 300 kyr?

International Journal of Astrobiology ◽

10.1017/s1473550414000512 ◽

2014 ◽

Vol 14 (3) ◽

pp. 375-378 ◽

Cited By ~ 8

Author(s):

Adrian L. Melott ◽

Ilya G. Usoskin ◽

Gennady A. Kovaltsov ◽

Claude M. Laird

Keyword(s):

Late Pleistocene ◽

Mass Extinction ◽

Past Research ◽

The Earth ◽

Middle And Late Pleistocene

AbstractFirestone (2014) asserted evidence for numerous (23) nearby (d < 300 pc) supernovae (SNe) within the Middle and Late Pleistocene. If true, this would have strong implications for the irradiation of the Earth; at this rate, the mass extinction level events due to SNe would be more frequent than 100 Myr. However, there are numerous errors in the application of past research. The paper overestimates likely nitrate and14C production from moderately nearby SNe by about four orders of magnitude. Moreover, the results are based on wrongly selected (obsolete) nitrate and14C datasets. The use of correct and up-to-date datasets does not confirm the claimed results. The claims in the paper are invalid.

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