The Global Carbon Cycle and Climate Change

Scaling Ecological Energetics from Organism to the Biosphere

David E. Reichle

• Publisher: Elsevier
• Year: 2019
• ISBN:
  9780128217672
• Topic: Ciencias biológicas
• Subtopic: Ciencia medioambiental

The Global Carbon Cycle and Climate Change examines the global carbon cycle and the energy balance of the biosphere, following carbon and energy through increasingly complex levels of metabolism from cells to ecosystems. Utilizing scientific explanations, analyses of ecosystem functions, extensive references, and cutting-edge examples of energy flow in ecosystems, it is an essential resource to aid in understanding the scientific basis of the role played by ecological systems in climate change.

This book addresses the need to understand the global carbon cycle and the interrelationships among the disciplines of biology, chemistry, and physics in a holistic perspective. The Global Carbon Cycle and Climate Change is a compendium of easily accessible, technical information that provides a clear understanding of energy flow, ecosystem dynamics, the biosphere, and climate change.

"Dr. Reichle brings over four decades of research on the structure and function of forest ecosystems to bear on the existential issue of our time, climate change. Using a comprehensive review of carbon biogeochemistry as scaled from the physiology of organisms to landscape processes, his analysis provides an integrated discussion of how diverse processes at varying time and spatial scales function. The work speaks to several audiences. Too often students study their courses in a vacuum without necessarily understanding the relationships that transcend from the cellular process, to organism, to biosphere levels and exist in a dynamic atmosphere with its own processes, and spatial dimensions. This book provides the template whereupon students can be guided to see how the pieces fit together. The book is self-contained but lends itself to be amplified upon by a student or professor. The same intellectual quest would also apply for the lay reader who seeks a broad understanding." --W.F. Harris

• Provides clear explanations, examples, and data for understanding fossil fuel emissions affecting atmospheric CO2 levels and climate change, and the role played by ecosystems in the global cycle of energy and carbon
• Presents a comprehensive, factually based synthesis of the global cycle of carbon in the biosphere and the underlying scientific bases
• Includes clear illustrations of environmental processes

Chapter 1

An introduction to ecological energetics and the global carbon cycle

abstract

The study of ecological systems utilizes bioenergetics to understand the functioning of entire ecosystems. Energy is essential for life on Earth. An organism with a positive energy balance is a successful organism in nature. Organisms and ecosystems have, consequently, evolved as highly efficient thermodynamic systems. Bioenergetics deals with the energy requirements and the processing of energy by organisms. Since biologically utilized energy is the energy stored in carbon molecules, ecosystem metabolism necessarily deals with the carbon balance of the entire ecosystem. Ecosystem carbon balances for different types of ecosystems form the basis for global carbon balance calculations.

Keywords

Bioenergetics; Carbon balance; Carbon chemistry; Carbon cycle; Carbon cycle models; Climate change; Ecological energetics; Ecosystem metabolism; Greenhouse effect

1. 1.1 Recommended Reading 

Energy is essential for life on Earth. An organism with a positive energy balance is generally a successful organism in nature. Organisms and ecosystems have, consequently, evolved as highly efficient thermodynamic systems. Bioenergetics deals with the energy requirements and the processing of energy by organisms. The term is most often used in reference to animals, but also applies to plants. Plants have evolved the unique photosynthetic process, using sunlight to split water molecules and manufacture organic carbon molecules from atmospheric CO_2, thus converting radiant energy into chemical energy to support their metabolic requirements. In animal systems bioenergetics encompasses the procurement of the chemical energy in food, the digestion of food, subsequent metabolism, and the eventual energy expenditures required for living and reproducing. Bioenergetics involves, therefore, many aspects of the organism's physiology, thermal relationships, and behavior, and becomes very complex and complicated to quantify. Bioenergetics has become a very sophisticated tool in animal husbandry, for it deals with the efficiency by which animal protein can be produced economically. By the 1960s, bioenergetics as applied to free-living animals had bifurcated into two fields of study, one approach emphasizing behavioral biology where the animal's activity patterns were studied in relation to its energy balance with its environment, and another physiological approach dealing with the metabolism of the free-living organism. In actuality both these approaches are necessary to understand the thermodynamics of organisms in nature (Reichle et al., 1975).

By the 1970s the growing field of ecology began to utilize bioenergetics to understand the functioning of entire ecosystems. Thus, the study of ecological, or ecosystem, energetics developed. Ecosystem energetics addresses the energy balance of the entire ecosystem and all its trophic levels. It consists of the ecosystem's metabolism—its primary productivity, trophic level exchanges, turnover and decomposition of detritus, growth, and reproduction. Since biologically utilized energy is the energy stored in carbon molecules, ecosystem metabolism necessarily deals with the carbon balance of the entire ecosystem (Lindeman, 1942; Odum, 1957; Smalley, 1960; Teal, 1962; Macfadyen, 1964; Phillipson, 1966; Woodwell and Botkin, 1970; Reichle et al., 1973). Besides plant photosynthesis and trophic level energetics, understanding the carbon metabolism of the entire ecosystem, above and below ground, includes death and decomposition to complete the ecosystem's carbon balance (net ecosystem production) with the environment. This academically intriguing subject suddenly took on tremendous societal relevance beginning in the 1980s, with the growing concern over the combustion of fossil fuels and the resulting CO₂ emissions to the atmosphere, leading to the greenhouse effect and global warming.

What did we know about the global cycle of carbon? And, when did we know it (Rich, 2018)? Ecosystem carbon balances for different types of ecosystems, when used with the geographic distribution of ecosystem types, or biomes, formed the basis for early global carbon balance calculations (Craig, 1957; Revelle and Suess, 1957; Bolin, 1970). As the modeling of ecosystem bioenergetics advanced, it became possible to construct dynamic global carbon models of the biosphere, which were functionally based and could, consequently, permit questions to be asked about the biosphere's response to changing atmospheric CO₂ levels or rising temperatures or changing land use cover or feedback loops such as oxidation of Arctic tundra, glacial melting, ocean outgassing, etc (Trabalka, 1985; Trabalka and Reichle, 1986). These questions remain very pertinent and central to the debate today on the consequences of climate change.

This text begins with an introduction to ecological energetics in Chapter 1. Chapter 2 defines energy terms, introduces the physical laws of energy, and discusses how the basic principles of thermodynamics govern biological as well as physical systems. Chapter 3 is a primer on energy relationships between organisms and the environment. Chapter 4 covers the biological energy transformations of photosynthesis and energy conversion efficiencies. In Chapter 5 the energy processing by animals, their metabolism, and energy budgets are examined. Chapter 6 examines how species adapt thermally to their environments. Chapter 7 addresses the energy exchange between plants and animals, ecological energetics, food chains, and the trophic level concept. Then in Chapter 8, the complexities of energy flow in ecosystems are covered. Subsequently, Chapter 9 examines the concept of ecosystem productivity; and then in Chapter 10 the global carbon cycle and the biosphere are reviewed. Chapter 11 examines how the anthropogenic emissions of CO₂ and land use change have altered the natural global carbon cycle and have influenced climate change. Ultimately, humankind will have policy decisions to make about fossil energy use to avoid the negative climatic consequences of having changed the biosphere's carbon cycle (Chapter 12).

Before continuing, I need to make several brief comments about references. Much of the ecological energetics and productivity data from the decades of the mid-1960s to the mid-1980s, particularly during the International Biological Program, are contained in the proceedings of international conferences, which are now nearly inaccessible to many. I have identified these publications and extracted pertinent information from these sources so that it can remain in the mainstream of scientific literature. Secondly, I have sought permission to reproduce select graphs and illustrations contained in benchmark publications under copyright by publishers of books and scientific journals, so that they are available to those without the privileges of access to these sources through institutional library IT agreements. And lastly, when possible, I have referenced key data whenever they were published in government-sponsored symposia and reports; and since they are in the public domain, I have provided their urls for convenient, direct IT access by the reader.

1.1 Recommended Reading

Bolin B, Degens E.T, Kempe S, Ketner P, eds.  The Global Carbon Cycle. SCOPE . 13. New York: John Wiley and Sons; 1979:491. https://www.researchgate.net/publication/40170880_The_Global_Carbon_Cycle_SCOPE_Report_13/.

Odum H.T. Trophic structure and productivity of Silver Springs, Florida.  Ecol. Monogr.  1957;25:55–112. doi: 10.2307/1948571.

Phillipson J. Ecological energetics. New York: St. Martin’s Press; 1966:57. https://www.worldcat.org/title/ecological-energetics/oclc/220312888/.

Reichle D.E, O’Neill R.V, Harris W.F. Principles of Energy and Material Exchange in Ecosystems. In: W. H. van Dobben and R. H. Lowe-McConnell, ed.  Unifying Concepts in Ecology . The Hague: W. Junk Pub; 1975:27–43 302 pp. https://link.springer.com/chapter/10.1007/978-94-010-1954-5_3/.

Chapter 2

The physical and chemical bases of energy

abstract

Energy is the capacity to do work. Energy can exist in various forms, but those of greatest importance to living organisms are mechanical, chemical, radiant, and heat energy. All forms of energy are interconvertible; when conversions do occur, they do so according to rigorous laws of exchange. These are the Laws of Thermodynamics. Enthalpy is the total potential energy of a system. Entropy is a measure of the disorder, or randomness, of a system.

Keywords

Carbon; Carbon forms; Chemical energy; Energy forms; Enthalpy; Entropy; Gaia hypothesis; Heat energy; Power; Solar radiant energy; Temperature; Thermodynamic laws; Work

1. 2.1 Energy, work, and power
   1. Calories and Joules
2. 2.2 The different forms of energy
   1. Chemical energy
   2. Radiant energy
   3. Heat energy
3. 2.3 The Laws of Thermodynamics
   1. The First Law of Thermodynamics
   2. Work
   3. Enthalpy
   4. The Second Law of Thermodynamics...