Carbon Cycle
The carbon cycle is the process through which carbon is exchanged between the atmosphere, oceans, biosphere, and geosphere. It involves various processes such as photosynthesis, respiration, decomposition, and combustion, which contribute to the movement of carbon in different forms. This cycle plays a crucial role in regulating Earth's climate and sustaining life on the planet.
8 Key excerpts on "Carbon Cycle"
eBook - ePubThe Global Carbon Cycle and Climate Change
Scaling Ecological Energetics from Organism to the Biosphere
- David E. Reichle(Author)
- 2019(Publication Date)
- Elsevier(Publisher)
...Chapter 10 The global Carbon Cycle and the biosphere Abstract Industrialization and changes in the landscape have disturbed natural geochemical cycles of carbon and other elements significantly for several centuries. Fossil fuel emissions are the main contributor, along with deforestation and cement production. Projection of future trends in atmospheric CO 2 and global carbon flows, under human disturbance, requires understanding of the natural exchanges between atmosphere, marine and terrestrial ecosystems, and geosphere pools. Regulation of the rates of flux in the global Carbon Cycle occur in enumerable biogeochemical processes, but overall through major feedbacks in the biogeochemical cycle of carbon through weathering, photosynthetic fixation, respiratory metabolism, and the ocean calcium carbonate buffering system...
eBook - ePub- Brian Dawson, Matt Spannagle(Authors)
- 2008(Publication Date)
- Routledge(Publisher)
...Carbon Cycle The Carbon Cycle refers to the processes by which carbon moves between the atmosphere, the terrestrial (land) system, and the oceans. Carbon is constantly moving between the three active reservoirs, and these exchanges are called carbon fluxes. Understanding how the Carbon Cycle works, and how these fluxes influence carbon dioxide (CO 2) concentrations in the atmosphere, is essential to understanding how anthropogenic greenhouse gas emissions influence the global climate. Reservoirs that absorb more CO 2 from the atmosphere than they emit to the atmosphere are termed carbon sinks. In total around 41,000 billion tonnes (or gigatonnes—Gt) of carbon (C) are available for exchange between the three principal reservoirs. The major reservoir of carbon is the ocean, which is estimated to contain around 38,000 GtC, or 93% of all exchangeable carbon. The ocean can be further subdivided into the surface ocean (down to about 100 m), which contains around 1,000 Gt C, and the deep ocean, which contains the remaining 37,000 GtC. The land carbon reservoir is estimated to contain just over 2,000 GtC, about 5% of exchangeable carbon. Of this, approximately 30% is stored in vegetation and other living organisms and the remainder in the soil and detritus. The atmosphere is the smallest of the three active reservoirs and is estimated, at present, to contain around 800 GtC, roughly 2% of exchangeable carbon. There is also a vast reservoir of geological carbon (20,000,000 Gt) stored in the earth’s crust, mainly as carbonate rocks. Of this, a small fraction (about 5,000 Gt) is stored as fossil fuels (coal, oil, and natural gas) and methane hydrates (5,000–10,000 Gt)...
eBook - ePub- Andrew H. Knoll, Don E. Canfield, Kurt O. Konhauser, Andrew H. Knoll, Don E. Canfield, Kurt O. Konhauser(Authors)
- 2012(Publication Date)
- Wiley-Blackwell(Publisher)
...3 THE GLOBAL Carbon Cycle: GEOLOGICAL PROCESSES Klaus Wallmann 1 and Giovanni Aloisi 1,2 1 Leibniz Institute for Marine Sciences (IFM-GEOMAR), Wischhofstrasse, 1–3; 24148, Kiel, Germany 2 UMR CNRS 7159LOCEAN, Universite Pierre et Marie Curie, Paris, France 3.1 Introduction In this chapter, we will discuss the geological Carbon Cycle including all processes controlling the distribution of carbon between the interior of the Earth, the lithosphere, the hydrosphere and the atmosphere (Fig. 3.1, Table 3.1). Our discussion focuses on the geochemical evolution of carbon inventories and fluxes on a multi-million year timescale. We will first address the magnitude of carbon fluxes in the pre-human Holocene and then over the last million years. We next examine the feedbacks stabilizing the distribution of carbon on our planet and present a balanced geological Carbon Cycle. Subsequently, we explore proxies and models to explain how carbon cycling may have changed over the Earth’s geological history in parallel with its biological and geological evolution. 3.2 Organic carbon cycling Land plants and phytoplankton use solar energy to convert atmospheric CO 2 into biomass via photosynthesis. The overall stoichiometry of photosynthesis can be expressed as: (3.1) where the simple carbohydrate C(H 2 O) represents organic carbon formed by this process. Molecular oxygen (O 2) is released as an important by-product of this reaction (see Chapter 7). Most of the biomass formed by photosynthesis, however, is rapidly consumed by microorganisms living in soils and in the oceans. Just as humans do, they use the biomass as an energy resource and recycle CO 2 into the atmosphere (electron acceptors other than O 2 are also used to oxidize organic matter as described below): (3.2) This respiration process consumes more than 99% of the biomass produced by photosynthesis both on land and in the sea (Table 3.2)...
eBook - ePub30-Second Climate
The 50 most topical events, measures and conditions, each explained in half a minute
- Joanna D Haigh(Author)
- 2019(Publication Date)
- Ivy Press(Publisher)
...Every year about 25 per cent of the CO 2 in the atmosphere is removed by plants conducting photosynthesis and by CO 2 dissolving at the ocean surface. However, almost the same amount of CO 2 is released into the atmosphere by respiration and wildfires on land and by CO 2 escaping dissolution at the ocean surface, representing a massive annual cycling of carbon. Earth’s climate and Carbon Cycle are tightly linked. Changes in atmospheric CO 2 alter the strength of the greenhouse effect, and changes in climate alter the balance between CO 2 taken up and released by the oceans and biosphere. Importantly, human activities are leading to increases in both CO 2 and methane in the atmosphere. 3-SECOND EVENT The term ‘Carbon Cycle’ refers to the exchanges of carbon between the Earth’s atmosphere, oceans, terrestrial biosphere and geological reservoirs by natural processes and human activities. 3-MINUTE CYCLE Since the Industrial Revolution the concentration of atmospheric CO 2 has increased by more than 40 per cent as a result of fossil-fuel burning, deforestation and other human activities. However, the rise in atmospheric CO 2 concentration would have been twice as large if not for the ocean and the plants and soils on land, which have removed about half of our carbon emissions from the atmosphere. As climate change progresses, these removal rates are expected to decline, thus further intensifying the effects. RELATED TEXTS See also HEAT RADIATION & THE GREENHOUSE EFFECT CLIMATE FORCING FACTORS & RADIATIVE FORCING CLIMATE PREDICTIONS TOWARDS ZERO CARBON 3-SECOND BIOGRAPHY INEZ FUNG 1949– Hong Kong/American climate scientist who deduced the terrestrial carbon sink and pioneered its representation in climate models 30-SECOND TEXT Heather D...
eBook - ePubThe Global Carbon Cycle
Integrating Humans, Climate, and the Natural World
- Christopher B. Field, Michael R. Raupach, Christopher B. Field, Michael R. Raupach(Authors)
- 2012(Publication Date)
- Island Press(Publisher)
...PART IV The Carbon Cycle of the Land 14 A Primer on the Terrestrial Carbon Cycle: What We Don’t Know But Should Jonathan A. Foley and Navin Ramankutty The terrestrial biosphere is an integral component of the global Carbon Cycle. Carbon is brought into the terrestrial biosphere through photosynthesis, and it is released back to the atmosphere through plant respiration, microbial respiration (or “decomposition”), fires, and some human land use practices. At times when photosynthesis exceeds the sum of plant respiration, microbial respiration, fires, and land use releases, there is a net sink of carbon from the atmosphere into ecosystems. When photosynthesis is less than the sum of the other terms, there is a net source from ecosystems to the atmosphere. On seasonal timescales, the gain and loss of carbon in terrestrial ecosystems is evident from subtle changes in atmospheric CO 2 concentrations—the seasonal “wiggles” in the Mauna Loa curve are a famous example of this phenomenon. But it is on longer timescales, from decades to centuries, that the Carbon Cycle of the terrestrial biosphere can significantly affect the CO 2 levels in the atmosphere and become important to the climate system. On these longer timescales, the amount of carbon stored in the terrestrial biosphere is the result of the balance between net primary productivity (NPP, the net accumulation of carbon through photosynthesis minus plant respiration over a year) and carbon losses through decomposition, land use, fires, and other disturbances (Figure 14.1). The scientific community currently believes that the terrestrial biosphere has been acting, on average, as a net sink of atmospheric carbon. In fact, terrestrial ecosystems appear to be absorbing a significant fraction of anthropogenic CO 2 emissions (from fossil-fuel combustion and, to a lesser extent, cement production) during the past few decades—thereby keeping atmospheric CO 2 levels lower than they would otherwise be...
eBook - ePubDebunking The Myth Of Human Made Climate Change
Challenging the Construction of a theory which uses manipulation to gain acceptance
- Michael J Cole, White Magic Studios(Authors)
- 2021(Publication Date)
- Maple Publishers(Publisher)
...5.4 The Carbon Cycle - The Natural Carbon Cycle on Earth 1. The element of carbon, number six in the periodic table, is a prevalent substance in various forms or state in compounds of all matter and all living or dead matter. It is stored in all mediums of liquids, rocks, plant life, human life and gases. It is released due to natural processes like volcanic eruptions, decaying materials and processes such as tectonic plate movements and oceanic interfaces with the atmosphere. This cycle of releases and absorption, including photosynthesis where plants taking in CO 2 and emit oxygen, is an ongoing process and is, in effect, a balancing mechanism to keep the whole dynamic within parameters and levels so that it remains stable – in effect to keep the environment suitable for habitation and sustainability. 2. To put some value on this process let’s look at the storage sizes of carbon and the various parts of the planet. The atmosphere (surface gases) contains around 800 giga tons (giga = billion), the hydrosphere (all forms of water/ice) contains around 39,000 giga tons, the biosphere (all living things) contains around 2000 giga tons and the geosphere (all rocks and bedrocks) contains around 65,000,000 up to 100,000,000 giga tons. This is clearly a sizeable storage of carbon inherent in the natural world and the natural emissions generated (no human involvement). Let’s compare this to human emissions of CO 2 in our life style and industrial processes of 8.6 giga tons. It is clearly a very small fraction of the natural levels. To put this in perspective each year the ocean surface and exchanges is estimated at 90 giga tons – ten times that of human production. Other natural emissions dwarf human levels. 3. The release cycle of carbon and CO 2 in particular has fast and slow cycles. For example a volcanic eruption is fast, pumping millions of tons of CO 2 into the atmosphere in a short period...
eBook - ePub- Rattan Lal(Author)
- 2017(Publication Date)
- CRC Press(Publisher)
...Inorganic Carbon: Global Carbon Cycle William H. Schlesinger Department of Geology and Botany, Duke University, Durham, North Carolina, U.S.A. Abstract Changes in the quantity of carbon (C) in vegetation and soils play a major role in determining short- and long-term fluctuations in the concentration of carbon dioxide (CO 2) in earth’s atmosphere. Human activities, such as the irrigation of agricultural soils in arid regions, can alter the accumulation of pedogenic carbonate in soils. For comparative purposes, biogeochemists calculate the mean residence time (MRT). Although the amount of pedogenic carbonate in world soils is quite large, this pool of C is relatively sluggish. The long MRT of the pedogenic carbonate pool ensures that it will not become a major sink or source of atmospheric CO 2 over the next several centuries. INTRODUCTION The “global C cycle” is defined as the exchange of carbon (C) among the atmosphere, seawater, land vegetation, and soil reservoirs (Fig. 1). Each year dead plant materials entering the soil are decomposed by soil microbes that return carbon dioxide (CO 2) to the atmosphere. If the amount of land vegetation remains the same, the amount of CO 2 removed from the atmosphere by plant growth each year is balanced by the amount of plant death and decomposition. Such a perfect balance, however, is seldom seen. Changes in the quantity of C in vegetation and soils play a major role in determining short- and long-term fluctuations in the concentration of CO 2 in earth’s atmosphere. A portion of the atmospheric increase in CO 2, e.g., is because of the destruction of vegetation and the disturbance of soils by humans. MEAN RESIDENCE TIME (MRT) For comparative purposes, biogeochemists calculate the MRT or the amount of time C resides in each pool of the global C cycle before circulating to the others. For instance, a molecule of CO 2 spends, in average, about 5 years in the atmosphere before it enters the terrestrial biosphere or the oceans...
eBook - ePubThe Warming Papers
The Scientific Foundation for the Climate Change Forecast
- David Archer, Raymond Pierrehumbert, David Archer, Raymond Pierrehumbert(Authors)
- 2013(Publication Date)
- Wiley-Blackwell(Publisher)
...It appears that the warming will eventually occur, and the associated regional climatic changes so important to the assessment of socioeconomic consequences may well be significant, but unfortunately the latter cannot yet be adequately projected.2 Carbon in the AtmosphereA brief account of the key features of the exchange of carbon between the atmosphere, the living and dead organic matter on land (the terrestrial biosphere), and the oceans is essential as a basis for the discussion that follows. The intermediate layers (100–1000 m) of the oceans also play a central role both as a sink for excess atmospheric CO2and for heat. For these reasons some basic features of the Carbon Cycle will be outlined, based primarily on the recently published review by the Scientific Committee on Problems of the Environment (SCOPE) of the International Council of Scientific Unions (Bolinet al.,1979).The CO2concentration in the atmosphere has risen from about 314 ppm (parts per million, volume) in 1958 to about 334 ppm in 1979, i.e., an increase of 20 ppm, which is equivalent to 42 × 109tons of carbon. During this same period, about 78 × 109tons of carbon have been emitted to the atmosphere by fossil-fuel combustion. It has further been estimated that more than 150 × 109tons of carbon have been released to the atmosphere since the middle of the nineteenth century, at which time the CO2concentration in the atmosphere most likely was less than 300 ppm, probably about 290 ppm.By reducing the extent of the world forests (at present about 30 percent of the land surface) and increasing the area of farmland (at present about 10 percent of the land surface) man has also transformed carbon in trees and in organic matter in the soil into CO2. The magnitude of this additional emission into the atmosphere is poorly known...
