The Global Carbon Cycle and Climate Change: Scaling Ecological Energetics from Organism to the Biosphere

By David E. Reichle

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

• Language: English
• Publisher: Elsevier Science
• Release date: Nov 12, 2019
• ISBN: 9780128217672

David E. Reichle

David E. Reichle was the Associate Laboratory Director at the Oak Ridge National Laboratory for Environmental, Life, and Social Sciences, and the former director of its Environmental Sciences Division. He was also adjunct Professor of Ecology at the University of Tennessee. He has authored over 100 scientific articles on radionuclides in the environment and the metabolism of ecosystems, edited 4 books on productivity and carbon metabolism of ecosystems, and led development of several seminal government reports on greenhouse gas reduction technologies and carbon sequestration. He has served on many scientific advisory boards for the Department of Energy, the National Science Foundation, the Environmental Protection Agency, the National Academy of Sciences, and other academic institutions and business organizations. He is a Fellow of the American Association for the Advancement of Science and a recipient of a Scientific Achievement Award from the International Union of Forest Research Organizations, a Distinguished Service Award from the U.S. Department of Energy, and a Muskingum University Distinguished Alumni Service Award. He also served on the national board of Governors of The Nature Conservancy, and as Chairman of TNC’s Tennessee state chapter.

Book preview

The Global Carbon Cycle and Climate Change

Scaling Ecological Energetics from Organism to Biosphere

David E. Reichle

Associate Director, retired, Oak Ridge National Laboratory

Table of Contents

Cover image

Title page

Copyright

List of figures

List of tables

Author Bio

Foreword

Acknowledgments

Chapter 1. An introduction to ecological energetics and the global carbon cycle

Chapter 2. The physical and chemical bases of energy

2.1. Energy, work, and power

2.2. The different forms of energy

2.3. The Laws of Thermodynamics

2.4. Gaia hypothesis

2.5. Carbon and energy

Chapter 3. Energy relationships between organisms and their environment

3.1. Energy balance

3.2. Functional interrelationships affecting leaf temperature

3.3. Solar

3.4. Thermal energy

3.5. Energy balance of a leaf

3.6. Radiative energy balance of a forest

3.7. Energy exchange of animals

Chapter 4. Biological energy transformations by plants

4.1. Solar radiation

4.2. Photosynthesis

4.3. Strategies for coping with environmental constraints

4.4. Energy conversion efficiencies

Chapter 5. Energy processing by animals

5.1. Metabolism

5.2. Free energy

5.3. Respiration

5.4. Energy value of foods

5.5. Digestion and assimilation

5.6. Respiration rates

5.7. Energy costs of digestion

5.8. Food energy budget for an individual

5.9. Why pork is cheaper than beef and chicken costs least of all

Chapter 6. Species adaptations to their energy environment

6.1. The limits of survival

6.2. Adaptation to the energy environment

6.3. Phenological relationships

6.4. Extreme environments

Chapter 7. Food chains and trophic level transfers

7.1. Food chains

7.2. Population dynamics and food chains

7.3. Food webs

7.4. Trophic levels

7.5. Trophic level efficiencies

7.6. Trophic structure of different ecosystems

Chapter 8. Energy flow in ecosystems

8.1 Ecosystem energetics

8.2 Ecosystem production equations

8.3 Measurement of pools and fluxes

8.4 The carbon cycle in ecosystems

8.5 Comparison of carbon metabolism among ecosystems

8.6 Net ecosystem production and net ecosystem exchange

8.7 Emergent properties of ecosystems

Chapter 9. Ecosystem productivity

9.1. Terrestrial ecosystems

9.2. Freshwater ecosystems

9.3. Marine ecosystems

9.4. Secondary production

9.5. Global biome-scale production

9.6. Factors affecting global productivity

9.7. Scaling from stand to the planetary boundary layer

Chapter 10. The global carbon cycle and the biosphere

10.1. The components of the global carbon cycle

10.2. Carbon cycle regulators

10.3. Units of measure for the global scale

10.4. History of carbon dioxide in the atmosphere

10.5. Uptake of carbon dioxide by the oceans

10.6. Carbon exchange between the atmosphere and terrestrial ecosystems

10.7. Modeling carbon in the biosphere

Chapter 11. Anthropogenic alterations to the global carbon cycle and climate change

11.1. Changing atmospheric concentrations of CO2

11.2. The greenhouse effect

11.3. Climate change

11.4. Greenhouse gases

11.5. Anthropogenic contributions to atmospheric CO2

11.6. Where are the CO2 emissions being generated?

11.7. Carbon cycle model projections of future atmospheres

11.8. Climate changes and climate model projections for the future

11.9. The effects of climate change

Chapter 12. Carbon, climate change, and public policy

12.1. What are the potential consequences of inaction?

12.2. Do we know enough?

12.3. International accords

12.4. Mitigation and adaptation

12.5. The economics of clean energy

12.6. What has been the impedance?

12.7. Is it too late to act?

Chapter 13. Postscript

Chapter 14. Suggested classroom uses of this book

Bibliography

Author Index

Subject Index

Copyright

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Notices

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List of figures

Figure 3.1 Energy exchange of the Earth and atmosphere for the northern hemisphere (100 units = 0.485 cal cm−² min−¹) based upon a solar constant value of 1.94 cal cm−² min−¹17

Figure 3.2 Global map of global horizontal radiation on the earth’s surface, kWm−².19

Figure 3.3 Radiation exchange for a leaf.19

Figure 3.4 The boundary layer between a leaf and its environment.25

Figure 3.5 The oak forest of Virelles-Blaimont energy balance from 25 May to 24 October, 1967 (calcm−²). So, extraatmosphere solar radiation on a horizontal surface (short waves); aSo, extraatmospheric solar radiation reflected by Earth-atmosphere system; Soabs, solar radiation absorbed by atmosphere; S, direct solar radiation on a horizontal surface; U, extraatmospheric upward radiation (long waves); D, diffuse scattered radiation on a horizontal surface (short waves); G, global radiation on a horizontal surface (S+D) (short waves); Te, terrestrial radiation (long waves); A, atmospheric radiation (long waves); aS, reflected solar radiation; aD, reflected diffuse radiation, aG, reflected global radiation; aNA, reflected atmospheric radiation; apG, global radiation utilized in net photosynthesis; Q1, short-wave radiation balance (G - aG); Q2, long-wave radiation balance (A - Te); Q, short- and long-wave radiation balance (G - aG+A - aNA - Te); QG, sensible heat flux in soil; QV, sensible heat flux in vegetation; K, sensible heat turbulent flux; V, latent heat in evapotranspiration; QR, latent heat in water condensation; Qh, advective sensible heat; Qprec, sensible heat flux in precipitation water. Parameters of the stand (per ha): biomass, 156 ton; net primary production (ground), 14.6 ton. Exchange aerial surfaces (haha−¹): foliage (2 faces) of trees, 14; bark of trees, 2; herb layer, 2; litter, 1.5; total exchange surfaces (except litter, 18haha−¹). Figures in brackets are estimated values (metric ton=10⁶g).35

Figure 3.6 Energy exchange for a lizard in its natural desert environment, showing the energy flows to the desert surface and to the lizard.37

Figure 3.7 Core-shell (two-layer) model for a lizard and a schematic representation of the thermal energy flows with its environment (Porter et al., 1973).39

Figure 3.8 Model predicted seasonal behavior patterns for the desert iguana, Diposaurus dorsalis, compared to behavioral observations shown as solid bars.40

Figure 4.1 Electromagnetic wavelength distribution of radiant energy.44

Figure 4.2 Schematic of a chloroplast from a plant cell.46

Figure 4.3 Photosystem II, the photolysis of H2O, and Photosystem I, producer of ATP and NADPH, both occurring in the thylakoid membrane of the chloroplast.47

Figure 4.4 The Calvin cycle. Atoms are: black - carbon, white - hydrogen, red - oxygen, pink - phosphorus.48

Figure 4.5 ADP-ATP cycle fueled by the glycolysis of a glucose substrate.50

Figure 5.1 Relationship between enthalpy (H), free energy (G), and entropy (S).56

Figure 5.2 Summary of anaerobic respiration: the metabolic pathway of glycolysis.60

Figure 5.3 The citric acid or Kreb’s cycle.61

Figure 5.4 Radioactive elimination curve for two cryptozoan species (Parcoblatta sp., the wood roach, and Sphaeroderus stenostomus, a snail-feeding carabid ground beetle) fed with ¹³⁴Cs isotope-tagged food.70

Figure 5.5 Idealized relationship between the metabolic rate of a mouse and environmental temperature. BMR, basal metabolic rate; MR, maximal rate; Tlc, lower critical temperature; Tuc, upper critical temperature; Tb, body temperature.75

Figure 5.6 Energy flow in an organism showing the categories of energy allocation and loss.76

Figure 6.1 Chemical reaction rate plotted against temperature, °C, change.81

Figure 6.2 Comparison of respiration and photosynthesis with temperature.82

Figure 6.3 Response of ectotherms and endotherms to increasing temperature.83

Figure 6.4 The phenology, leaf expansion and senescence, and biomass growth components of a soybean simulation model interact dynamically and demonstrate how each are influenced by weather variables. TDM, Total above ground dry matter, RDM, Below ground dry matter, LDM, Leaf dry matter, STDM, Stem dry matter, SDM, Seed dry matter, CG, Crop growth, SG, Seed Growth, MG, Relative maturity group, Stem Term, Stem termination type (Indeterminate vs Semi-determinate), RH, Relative humidity, ET, Reference evapotranspiration, Irrig., Irrigation.90

Figure 6.5 Flowering phenophases in a temperate deciduous forest.91

Figure 6.6 Phenological degree-day summation predicting flowering for 133 species of vascular plants in an oak-hickory forest at Oak Ridge, Tennessee.92

Figure 7.1 Scheme of matter and/or energy flow for a food chain or trophic level. MR, total material removed by the organism or population; NU, material removed, but not consumed; C, consumption; FU, rejecta; F, egesta; U, excreta; A, assimilation; D, digested energy/material; P, production; Pg, production due to body growth; Pr, production due to reproduction; R, respiration; ΔB, changes in mass of the individual or population; E, elimination. Nomenclature after Petrusewicz and Macfadyen, 1970.98

Figure 7.2 The time delays between peaks of radioactivity concentrations in trophic levels reflect the temporal delay in the flux of energy along food chains.99

Figure 7.3 Fluctuation of biomass and numbers of a hypothetical population in time. Assumptions are: a life span of 3years, one litter per year, maturation in 1year, completion of growth of young in 4months, and a stable population and reproductive rate from year to year. The insert shows partitioning of biomass for net production per year. The net production exceeds the biomass peak because of the production of animals dying prior to the time of biomass peak. BO, biomass of current generation; B1,2 … n, cumulative biomass from earlier generations; EO, elimination and MR, material removed by predation.104

Figure 7.4 Food web showing the interactions between organisms across trophic levels in the Lake Ontario ecosystem. Primary producers are outlined in green, primary consumers in orange, secondary consumers in blue, and tertiary (apex) consumers in purple. Arrows point from an organism that is consumed to the organism that consumes it.105

Figure 7.5 A stylized trophic level pyramid with the area in each level representing biomass or chemical energy content.108

Figure 7.6 Ecological pyramids comparing biomass and energy for trophic levels from different aquatic ecosystems. Notation: C1, primary consumer; C2, secondary consumer; C3, tertiary consumer; P, Producer; S, saprotroph.109

Figure 7.7 Heterotroph biomass as a function of primary production per unit plant biomass. The six points represent ecosystem types: Cs, cone spring; Df, deciduous forest; Po0, pond; Sm, salt marsh; Tu, tundra; Tf, tropical forest.114

Figure 8.1 Oxygen production during the light bottle:dark bottle experiment.125

Figure 8.2 A diagrammatic representation of the pathways of energy and carbon flux in a freshwater ecosystem: Silver Springs, Florida. Carbon values given in Table 8.1.131

Figure 8.3 Conceptual representations of stream spiraling and uptake length affecting carbon metabolism in flowing waters.134

Figure 8.4 The biogeochemical cycle of carbon in the ocean ecosystem.137

Figure 8.5 The carbon cycle in a mesic deciduous forest in Tennessee. Trees, left to right, represent understory, dominant Liriodendron tulipifera, and all other overstory trees. Decomposers are separated by surface litter and soil zones. Heterotrophs are invertebrates only for both herbivores and carnivores; values do not include vertebrates. All values are in g C m−² for biomass (boxes, upper left standing crop; lower right, annual increment) and in g C m−² yr−¹ for fluxes (arrows).141

Figure 8.6 Approximate turnover times in years representative for carbon in major world ecosystem types: vegetation in green and soils/sediments in brown, approximate average times in years derived from the sources below.153

Figure 9.1 The global distribution of biomes, or ecofloristic zones mapped by the United Nations Food and Agricultural Organization. Source: Ruesch and Gibbs, 2008.159

Figure 9.2 Ecofloristic zones (biomes) as determined by mean annual temperature and annual precipitation.160

Figure 9.3 IPCC Tier-1 Global Biomass Carbon Map (above and below-ground) for the Year 2000 in metric tons carbon per hectare (100gm−²).174

Figure 9.4 Patterns of ocean circulation.177

Figure 10.1 The natural global cycle of carbon showing the major reservoirs (pools) and pathways (fluxes) of carbon flow in the biosphere, as illustrated in the structure of an early, multidimensional box model.185

Figure 10.2 Interannual fluctuations in atmospheric CO2 concentrations reveal the breathing of the biosphere across the seasons of the year.186

Figure 10.3 Contours of soil carbon (kg C m−²) plotted on a Holdridge (1967) life-zone chart.201

Figure 10.4 A compartment model of the global carbon cycle with couplings to other elements. The model construct incorporates rapid ecological processes (A) with slow geologic processes (B) averaged over the latter portion of post-Cambrian time. (A) Landscapes is early Holocene (recent) time had approximately equal quantities of rapidly cycling (mostly photosynthetic) tissue from woody and nonwoody parts of plants. The latter probably were of negligible mass before the late Silurian Period about 400 million years ago. Estimated values and uncertainties are given in Table 10.7. (B) Summary of oceanic and lithospheric cycles. Note: 1mol carbon dioxide=12g carbon.202

Figure 11.1 Global atmospheric CO2 versus Mauna Loa CO2. Measurements at Mauna Loa reflect the global average derived from many worldwide monitoring stations.212

Figure 11.2 Atmospheric CO2 levels (parts per million, ppm) over the past 10,000 years. Blue line from Taylor Dome, Antarctica ice cores. Green line from Law Dome, Antarctica ice cores. Red line from direct atmospheric measurements at Mauna Loa, Hawaii.213

Figure 11.3 Global satellite measurements of atmospheric CO2 concentrations in July 2008 from the NASA Atmospheric Infrared Sounder (AIRS) on the Aqua satellite.214

Figure 11.4 The Greenhouse Effect.215

Figure 11.5 Comparison of global temperature and atmospheric CO2 concentrations from 1880 to 2010, with temperature deviations from historic norms.216

Figure 11.6 An estimate in 1990 of worldwide greenhouse gas emissions. Values are 10¹²g CO2-eq.218

Figure 11.7 Fossil fuel consumption by the world.223

Figure 11.8 Breakdown of annual worldwide greenhouse gas emissions by industrial sector in 2010. Values are 10¹²g CO2-eq.223

Figure 11.9 The world’s carbon cycle at the beginning of the 21st century as influenced by human activities, showing how carbon atoms flow between various reservoirs in the Earth system. Reservoir sizes are in Gt (10¹⁵ g) C; fluxes are in Gt C yr−¹. The red numbers and arrows show the additional fluxes and reservoir changes caused by humans, such as the burning of fossil fuels and land use changes, averaged over 2000–2009.228

Figure 11.10 The airborne CO2 fraction showing global carbon dioxide emissions (as gigatons of carbon without oxygen molecular weight added) from 1960 through 2012, and the amount of emitted CO2 that has remained in the atmosphere.231

Figure 11.11 The biological pump of carbon in the ocean.236

Figure 11.12 Future atmospheric CO2 levels as projected for the four RCP emission scenarios (IPCC SRES Report, 2007). All forcing agents' atmospheric CO2-equivalent concentrations (in parts-per-million-by-volume (ppmv)) according to four RCPs.237

Figure 11.13 Radiative-forcing components used by the IPCC in 2007 in the calculation of climate outcomes from four different representative concentration pathways (RCPs) dependent upon possible future levels of greenhouse gas emissions.238

Figure 11.14 The 10 hottest years globally.241

Figure 11.15 Despite technological improvements that increase corn yields, extreme weather events have caused significant yield reductions in some years.245

Figure 12.1 Schematic diagram illustrating current and/or projected impacts of climate changes on major components of marine and coastal ecosystems.254

Figure 12.2 Past and future ocean heat content changes (OHC). Annual observational OHC changes are consistent with each other and consistent with the ensemble means of the CMIP5 models (Taylor et al., 2012) for historical simulations pre-2005 and projections from 2005 to 2017, giving confidence in future projections to 2100 (RCP2.6 and RCP8.5) (see the supplementary materials). The mean projected OHC changes and their 90% confidence intervals between 2081 and 2100 are shown in bars at the right. The inset depicts the detailed OHC changes after January 1990, using the monthly OHC changes updated to September 2018 (Cheng et al., 2017), along with the other annual observed values superposed.256

Figure 12.3 Worldwide greenhouse gas emission in 2005.260

Figure 12.4 Carbon flows in the energy system and sources of emissions in the United States in 1995 in millions of metric tons (10¹²gC).265

Figure 12.5 Carbon intensity of electricity: history and forward trends necessary to reach a zero-carbon electricity grid by mid-century.282

Figure 12.6 The world's economies vary considerably in how efficiently their GDPs utilize carbon-based fuels.283

List of tables

Table 2.1 Units of measure for energy in its various forms and transformations.6

Table 3.1 Transmission (langleys min−¹) of direct solar radiation through a canopy of red pine plantation.20

Table 3.2 Total emissivity, ε, all wavelengths and short-wave absorptivity of common bodies occurring in the natural environment (Handbook of Chemistry and Physics).23

Table 3.3 Typical albedo values for environmental surfaces on earth.24

Table 3.4 Typical thermal conductivities of environmental media, biological constituents, and other reference materials at ordinary temperatures.25

Table 3.5 Convection coefficients (calcm−² min−¹oC) for free convection in laminar flow. ΔT is the temperature difference in oC between the surface of the object and the surrounding air. L is the dimension of the plate in the direction of flow.26

Table 3.6 Rates of heat transfer (cal.cm−²min−¹) for forced convection across a flat plate as a model for a plant leaf in the environment. Values (cal.cm−²min−¹) are a function of the temperature differential between surface and air, dimension of the surface, and wind speed.27

Table 4.1 The energy value of different wavelengths of solar radiation.45

Table 4.2 Efficiencies of photosynthetic radiant energy conversion into biomass by plants.53

Table 5.1 Summary of aerobic respiration: The efficiency of ATP production by glycolysis.62

Table 5.2 Thermal equivalents (kcalL−¹) for different compounds.64

Table 5.3 Heats of combustion to H2O (L) and CO2 (g) at 25°C and constant pressure.66

Table 5.4 Energy values for plant parts and animal taxa.68

Table 5.5 Food assimilation for different foods and by different trophic level consumers reported in the scientific literature.69

Table 5.6 Values for the body weight exponential function, b, for different animal types.72

Table 5.7 The relationship between food energy and heat production, the calorigenic effect or specific dynamic action (SDA), in a dog fed 100 kcal day-1 of lean meat (protein) [columns 1-4], compared with the food energy and heat production equivalents to be obtained from a pure fat [columns 5-6] or carbohydrate [columns 7-8] diet.73

Table 5.8 Comparison of dietary energy utilization in the domestic pig and cow (values are % food energy ingested).77

Table 5.9 Rate of production and production efficiency in relation to dietary energy intake in farmed animals.78

Table 6.1 The development time of sea urchin eggs as a function of temperature demonstrates how energy (heat) affects biological processes, and how acclimation to warmer summer temperatures, or cooler winter temperatures, affects development. Natural populations of Paracentrotus lividus range between 13°C−28°C.85

Table 6.2 Some examples of adaptive strategies of plants and animals to their energy environment.86

Table 6.3 Some aspects of an energy budget for hummingbirds.88

Table 7.1 Comparison of productivity between mouse, deer, and elephant.104

Table 7.2 Ecological energetic efficiencies.110

Table 7.3 Values reported for ecological energetic efficiencies for different trophic levels.112

Table 7.4 Calculated ingestion, production, respiration, and egestion by heterotrophs in a grassland ecosystem in kcal m−² yr−¹ per 100kcalm−¹ yr−¹ net annual primary production.113

Table 7.5 Ecological energetic efficiencies for three different ecosystems (cal cm−² yr−¹).116

Table 8.1 Comparison of the carbon budgets of five aquatic ecosystems: Spartina Salt Marsh, GA (Teal, 1962); Silver Springs, FL (Odum, 1957); oligotrophic Lake Eckarfjärden, Sweden (Andersson and Kumblad, 2006); Lake Washington, WA (Eggers et al., 1978); eutrophic Lake Lawrence, MI (Wetzel and Rich, 1973). Units are: fluxes in kg C m−² yr−¹, standing crop in kg C m−¹).132

Table 8.2 Mean values and ranges for GPP, RE, and NEP for aquatic ecosystems Values are g O² m−² day−¹).142

Table 8.3 Comparison of the carbon budgets of eight terrestrial ecosystems: Spruce Forest, Sweden (Karlberg et al., 2007); Mesic Tulip Poplar forest, TN (Reichle et al., 1973); Oak-Pine forest, NY (Woodwell and Botkin, 1970); Tropical Rain Forest, Thailand (Tan et al., 2010); Shortgrass Prairie, CO (Andrews et al., 1974); Tundra (after Reichle, 1975); Agricultural ecosystems values from L. Ryszkowski (Reichle, 1981). Units are: fluxes in kg C m−² yr−¹, standing crop in kg C m−²).143

Table 8.4 Comparative metabolic parameters for six different forest ecosystems. All values above the dotted line are in kg C m−² and kg C m−² yr−¹; values below the dotted line are dimensionless indices.147

Table 8.5 Comparison carbon fluxes of five forest ecosystem using eddy covariance: WB=Walker Branch; TN, MMSF=Morgan Monroe State Forest, IN; HF=Harvard Forest, MA; UMBS=University of Michigan Biological Station, MI; WC=Willow Creek, WI. Units are: fluxes in kg C m−² yr−¹, standing crop in kg Cm−².150

Table 9.1 Conversion factors of units of measure for mass and energy values.159

Table 9.2 Summary of global area, annual net primary production (NPP), plant carbon content, and soil carbon content in broadly categorized terrestrial ecosystems.162

Table 9.3 Primary production and biomass estimates for the biosphere.164

Table 9.4 Net primary productivity in the ocean.167

Table 9.5 Secondary production (NSP) by consumers in different ecosystems. Values are for specific consumer groups, except where indicated by A=productivity for the entire animal trophic level.170

Table 9.6 Various estimates of total global production in carbon and energy units.172

Table 9.7 Ranking of the net primary productivity of the biomes based upon the values reported by the references cited in Chapter 8 and Tables 9.2 and 9.3.173

Table 9.8 Biomass of ecosystems of the main biomes each with distinct vegetative structure. Metric ton ha−¹ (= 10²gm−²).176

Table 10.1 Values, and uncertainties of parameters, in the global carbon cycle.189

Table 10.2 Units of measure for the global carbon cycle.191

Table 10.3 Atmospheric carbon dioxide fluxes (Gt C yr−¹ or 10¹⁵gC yr−¹). Errors represent±standard deviation of uncertainty estimates and not interannual variability which is larger. The atmospheric increase (first line) results from fluxes to and from the atmosphere: positive fluxes are inputs to the atmosphere (emissions); negative fluxes are losses from the atmosphere (sinks); and numbers in parentheses are ranges. Note that the total sink of anthropogenic CO2 is well constrained. Thus, the ocean-to-atmosphere and land-to-atmosphere fluxes are negatively correlated: if one is larger the other must be smaller to match the total sink, and vice versa.194

Table 10.4 Estimated oceanic carbon pools.195

Table 10.5 Carbon in major pools of the biosphere. Contemporary estimates using Whittaker & Likens, 1973 and IPCC 2014 in parentheses. Percentages of total carbon pools (columns 2 and 3) are based upon Reiner’s 1973 calculation using Bolin’s 1970 values.198

Table 10.6 Carbon balance in terrestrial detritus by biome (Schlesinger, 1979).200

Table 10.7 Simplified global carbon inventory and budget estimates for recent, early Holocene times. Values here are 10¹⁵gC yr−¹.203

Table 11.1 Internet sources of data relative to the issue of climate change.211

Table 11.2 Methane sources and sinks, both natural and anthropogenic (Schlesinger, 1997; after Prather et al., 1995). Units are 10¹²g CH4 yr−¹.219

Table 11.3 Warming increases (°C) projected by the radiative forcing functions resulting from different assumptions of GHG emission scenarios.242

Table 11.4 Estimated global NPP by terrestrial ecosystems.242

Table 11.5 Future sea level rise (in meters) projected from different radiative forcing function scenarios from assumptions of different GHG emissions.248

Table 12.1 Historical timeline of milestones in establishing international climate policy.261

Table 12.2 Cumulative CO2 emissions limits from a 2011 emissions baseline necessary to limit global warming to <1.5°C and <2°C, with associated probabilities.263

Table 12.3 The lifecycle carbon intensity of electricity sources: greenhouse gas emissions per kilowatt.266

Table 12.4 The potential of different terrestrial biomes to sequester carbon that might be sustained over a 25–50 year period.270

Table 12.5 Relative concentration pathways (RCPs) with pathway descriptions and integrated assessment models used by IPCC for the year 2100.277

Table 12.6 Future sea level rise (in meters) projected from different radiative forcing function scenarios from assumptions of different GHG emissions.279

Table 12.7 Projected annual economic damage estimates (in 2015 $) in the United States by 2090.280

Table 12.8 Estimated global macro-economic costs in 2030 relative to the baseline for least-cost trajectories toward different, long-term stabilization levels.281

Author Bio

David E. Reichle was the Associate Laboratory Director of the Oak Ridge National Laboratory for Environmental, Life, and Social Sciences, and the former Director of its Environmental Sciences Division. He was also an adjunct Professor of Ecology at the University of Tennessee. He has authored over 100 scientific articles on radionuclides in the environment and the metabolism of ecosystems, edited four books on productivity and carbon metabolism of ecosystems, and led development of several seminal government reports on greenhouse gas reduction technologies and carbon sequestration. He has served on many scientific advisory boards for the Department of Energy, the National Science Foundation, the Environmental Protection Agency, the National Academy of Sciences, and other academic institutions and business organizations. He is a fellow of the American Association for the Advancement of Science and recipient of the Scientific Achievement Award from the International Union of Forest Research Organizations, a Distinguished Service Award from the U.S. Department of Energy, and the Muskingum University Distinguished Alumni Service Award. He also served on the national board of governors of the Nature Conservancy and as Chairman of TNC’s Tennessee state chapter.

Foreword

Bioenergetics has long been a subject of research in animal husbandry and ecological research, where it served as an organizing principle in early ecosystem research (Odum, 1959). The metabolism of ecosystems and ecological energetics are subject areas that I always found to be fascinating, and ones that were researched intensely at the Oak Ridge National Laboratory (ORNL), in Oak Ridge Tennessee. I was recruited to ORNL as a new PhD from Northwestern University in 1964 to study the behavior of radionuclides in food chains—uptake, bioaccumulation, and potential pathways leading to human exposure. My postdoctoral fellowship was sponsored by what was then the US Atomic Energy Commission (now the US Department of Energy). One of the little-known facts in the history of American science is that the AEC was the first significant sponsor of modern ecological research in the United States, this role only several decades later being assumed by the National Science Foundation (Egerton, 2017). The Manhattan Project's 1943 Clinton Laboratories, managed by the University of Chicago's Metallurgical Laboratory, was the predecessor of ORNL; Union Carbide Corporation assumed responsibilities in 1947. By the time that I had arrived, WWII was over and research had shifted to the peaceful uses of atomic energy. My job title was biophysicist in the Radiation Ecology Section of the Health Physics Division; the Section was later to become the internationally renowned Ecological Sciences Division at ORNL (Auerbach, 1993). Our research team's scope quickly grew from examining the fate and effects of radionuclides in food chains leading to humans to studying the natural biogeochemical cycles that governed the movement of radionuclides in the environment—all of which were ultimately regulated by the metabolism of ecosystems.

Few in the scientific community, much less in the general public, knew what ecology was when the US Atomic Energy Commission began its ecological research programs in the early 1950s (Reichle and Auerbach, 2003). These programs, which antedated major support for ecosystem research by the National Science Foundation by several decades, were the foundation for modern ecosystem research in the United States (Coleman, 2010). Since ecologists at ORNL had been researching ecosystem carbon metabolism, we became the US R&D center for forest ecology and ecosystem modeling when US participation (1964–74) began in the International Biological Program (Smith, 1968; NAS, 2019). International collaboration continued for many years thereafter, and results of research on the deciduous forest biome culminated with publication of Dynamic Properties of Forest Ecosystems (Reichle, 1981). This research experience was an important reason why the AEC's successor, the Energy Research and Development Administration, and later the US Department of Energy (DOE), became a leading US agency studying the global carbon cycle.

The mission of DOE and its national laboratories was to promote the safe development of all energy technologies. Both the scientific experience gained from studying the carbon metabolism of ecosystems (Reichle and Auerbach, 1972) and the development of climate models to follow global fallout from weapons testing and the concern about a nuclear winter from nuclear weapons deployment, the national laboratories became early leaders in climate change research. The scientific experience gained in early environmental studies of the nuclear industry came full circle in the 1980s to examine the environmental consequences of a fossil fuel–based energy economy.

Ecological energetics is the study of the metabolism of plants, animals, microbes, and ecosystems. Knowledge about the functioning of ecological systems is necessary for our understanding of the metabolism of the biosphere, essential in adressing human-induced climate change, and quite possibly critical to protecting our global environment. This book is the product of a course in ecological energetics that I offered in the early 1970s in the then Graduate Program in Ecology at the University of Tennessee. I had intended the syllabus to be the basis for a textbook in bioenergetics, but somehow never found the time to write the book. Now 45   years later in retirement, I have the time, the field of ecology has matured, and bioenergetics, while an interesting chapter in basic ecology texts of the 1950–70s, has now assumed new societal relevance. Ecological energetics is the foundation for both understanding the metabolism of the biosphere and also the basis for addressing the potential future environmental impacts of climate change.

This book is a journey in time, scale, and complexity. It will be a journey following the flux of solar energy from the sun, and carbon from the atmosphere, through the living systems on earth. It will be a journey in scale—from milligrams to gigatons, from seconds to years, from square centimeters to hectares, and from the cell to the biosphere. This journey has rules which will govern our passage—the principles of thermodynamics, biochemistry, physiology, and ecology. Let us begin.

Suggested Reading

Coleman D.C. Big Ecology: The Emergence of Ecosystem Science. Berkeley-Los Angeles-London: Univ. Calif. Press; 2010:236. https://epdf.pub/big-ecology-the-emergence-of-ecosystem-science.html.

Egerton F.N. History of Ecological Sciences, Part 59: Niches, Biomes, Ecosystems, and Systems. 2017. https://www.researchgate.net/publication/320227603_History_of_Ecological_Sciences_Part_59_Niches_Biomes_Ecosystems_and_Systems/. .

Odum E.P.  Fundamentals of Ecology . 2nd Ed. Philadelphia and London: W. B. Sanders Co.; 1959:546.

Reichle D.E, Auerbach S.I. U.S. RadioecologicL Research Programs of the Atomic Energy Commission in the 1950s. Oak Ridge, TN: ORNL/TM-2003/280. Oak Ridge National Laboratory; 2003. http://www.osti.gov/bridge/.

Smith F.E. The international biological program and the science of ecology.  Proc. Nat’l Acad. Sci. USA . 1968;60(1):5–11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC539127/.

Acknowledgments

My career in ecology has been stimulated by a large number of individuals: my graduate school professor, Orlando Park of Northwestern University, one of the authors of The Great Apes, Alee, Emerson Park, Park, and Schmidt's Principles of Animal Ecology (1949), one of the first and perhaps best ecology texts from the Chicago School of ecology; Stanley Auerbach, founder of the Ecological Sciences Division (ESD) at the Oak Ridge National Laboratory (ORNL), and mentors and colleagues in ESD: Dac Crossley, Jerry Olson, George Van Dyne, Frank Harris; early leaders in ecological energetics: Howard Odum, Gene Odum, George Woodwell, Bob Whittaker, Dick Wiegert, David Gates, Jerry Franklin; European ecologists John Phillipson, Amian Macfadyen, John Satchel, Kasimierz Petrusewicz, Lech Ryszkowski, Paul Duvigneaud, and Helmut Lieth influenced me profoundly, both personally and through their seminal publications. The book has its origin in a course in ecological energetics that I offered in the Graduate Program in Ecology at the University of Tennessee, decades of research at ORNL, and has been nurtured through the encouragement and patience of my wife, Donna. Brenda Wyatt provided invaluable technical records assistance, and I am grateful to ORNL for providing access to IT library resources.

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 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 CO2, 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