Carbon Dynamics

by

Rebecca Abney, Chelsea Arnold, Michael Kaiser, Lixia Jin, Asmeret Asefaw Berhe

• LAST REVIEWED: 16 August 2021
• LAST MODIFIED: 27 April 2017
• DOI: 10.1093/obo/9780199363445-0065

Introduction

The biogeochemical cycle of carbon (C) in the earth system controls fluxes, pools, and transformations associated with life’s most fundamental element. As the most basic building block for all living organisms, organically bound C forms the basis for the overwhelming majority of food chains in ecosystems and global energy flows. The uptake of carbon dioxide (CO₂) by autotrophic organisms and photosynthetic transformation of light energy into chemical energy enables conversion of atmospheric CO₂ into structural materials for living organisms and ultimately fossil fuels. In the earth system, C exists in different forms and reservoirs, including gaseous, dissolved, and solid forms distributed and continually exchanged among the atmosphere, terrestrial, and aquatic spheres. The most important gaseous forms of C include CO₂ and methane (CH₄). The liquid phase includes different species of C found in water, including (1) dissolved CO₂ and carbonic acid (H₂CO₃) and its intermediates, (2) dissolved organic compounds (molecules <0.45 µm in size), (3) suspended organic and inorganic colloids/particles (typically >10s nm) containing C, and (4) raw oil. The solid phase comprises C (1) in rocks of organic and inorganic origin, in sedimentary rocks and sediments including coal, (2) on and in soils in the form of carbonates, (3) in dead not dissolved or suspended organic compounds, and (4) in the living biomass of microorganisms, plants, and animals. The C in the atmosphere, terrestrial, and aquatic systems can be characterized according to the amount of C stored in a given reservoir, its mean residence time (i.e., the time needed to exchange each C atom of the considered system or subsystem at least once), and the physical or chemical state of C in a given reservoir or as it exchanges among reservoirs. Different systems can be subdivided into active and inactive drivers of C dynamics based on the C mean residence times. Under natural conditions, almost the entire C stored in sediments or sedimentary rocks, for example, is considered to be inactive with mean residence times longer than 1,000 years. Contrastingly, the C stored in the atmosphere, surface oceans, plant biomass, and soil organic material in the soil is relatively active with residence times ranging from seconds to centuries. However, anthropogenic extractions of fossil fuel C from global sedimentary deposits, for example, have demonstrated how inactive C reservoirs can be rapidly transformed into highly active drivers of global C dynamics.

Historical Overview

To fully understand the field of C dynamics, it is important to recognize some of the earlier works that developed the fundamental concepts and principles that now serve as underpinnings for studying the biogeochemical cycling of C in the earth system. Archer and Pierrehumbert 2011 compiles some of the most important scientific works that have established the scientific basis for our understanding of global climate change. A few of these foundational studies are highlighted in this section.

• Archer, D., and R. Pierrehumbert, eds. 2011. The warming papers. Chichester, UK: John Wiley.

  A collection of the classic scientific papers that form the foundation of our current scientific understanding of climate change and its consequences. Available online by subscription.

• Arrhenius, S. 1896. On the influence of carbonic acid in the air upon the temperature of the ground. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science 41.251: 237–276.

  DOI: 10.1080/14786449608620846

  The work is credited with the development of modern climate science and the idea of climate sensitivity. Arrhenius first calculated the extent of warming that can be experienced due to the doubling of atmospheric concentration of CO₂.

• Callendar, G. S. 1938. The artificial production of carbon dioxide and its influence on temperature. Quarterly Journal of the Royal Meteorological Society 64.275: 223–240.

  DOI: 10.1002/qj.49706427503

  A seminal early work that related increased concentration of CO₂ in the atmosphere with rising global air temperature. This work partially inspired the measurement of atmospheric CO₂ concentration at the Mauna Loa observatory on the island of Hawaii by Charles David Keeling.

• Foote, E. 1856. Circumstances affecting the heat of the sun’s rays. American Journal of Science and Arts. 22:382–383.

  This work is credited for establishing that solar radiation causes a different degree of warming on air, depending on the type and concentration of gases present. In this work, Foote showed that CO₂ traps more heat than the other gases she investigated. Based on her findings, she theorized that differences in concentration of CO₂ in the earth’s atmosphere can change its temperature.

• Fourier, J. 1824. Annales de chimie et de physique 27. Paris: Annals of Chemistry and Physics.

  This work is widely credited for being the first to propose the greenhouse effect, describing the atmosphere as a glass house that allows light to come in but traps dark rays or heat from escaping. In addition, Fourier’s works in the 1820s established how distance from the sun determines the temperature of planets, sources and sinks of a planet’s energy, and the possibility that the earth’s atmosphere could act as an insulator. Fourier also advanced the idea that infrared radiation loss from a planet is equated to heat loss and that absorption of visible light by planetary objects converts it to infrared.

• Keeling, C. D. 1960. The concentration and isotopic abundances of carbon dioxide in the atmosphere. Tellus 12:200–203.

  DOI: 10.1111/j.2153-3490.1960.tb01300.x

  Keeling, the first person to make frequent and regular measurements of the concentration of CO₂ in the atmosphere, developed an isotopic approach to determine the diurnal changes in CO₂ release from plants and soil. Keeling also determined seasonal variations in CO₂ concentration and showed that the annual rate of increase in CO₂ concentration in the atmosphere that he was measuring matched the amount of C that was being released to the atmosphere by fossil fuel burning.

• Revelle, R., and H. Suess. 1957. Carbon dioxide exchange between the atmosphere and ocean and the question of an increase of atmospheric CO₂ during past decades. Tellus 9:18–27.

  DOI: 10.1111/j.2153-3490.1957.tb01849.x

  One of the seminal papers that drew scientific attention to the issue of fossil fuel burning and the implication of releasing organic C that has been stored in sedimentary rocks for hundreds of millions of years to the atmosphere.

• Tans, P. P., I. Y. Fung, and T. Takahashi. 1990. Observational constraints on the global atmospheric CO₂ budget. Science 247.4949: 1431–1438.

  DOI: 10.1126/science.247.4949.1431

  Combined measurements of atmospheric concentrations of CO₂, with partial pressures of CO₂ in surface oceans and general circulation model to determine the distribution of sources and sinks for atmospheric CO₂ around the globe, and the strength of the ocean and land sinks.

• Tyndall, J. 1861. On the absorption and radiation of heat by gases and vapors, and on the physical connexion of radiation, absorption, and conduction: The bakerian lecture. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science 22.146: 169–194.

  DOI: 10.1080/14786446108643138

  This was among the first works to demonstrate that different gases (later known as greenhouse gases) and vapors have distinct potential to absorb infrared radiation. This work provided the experimental basis for how human actions can change the temperature of the atmosphere by altering the concentration of the different gases in the atmosphere (i.e., the greenhouse effect).