Print this pageGeological
Perspectives of Global 
Climate
Change: Introduction and Overview*
By
Gerhard, L.C.,1 W.E. Harrison, 1 and B.M. Hanson2
Search and Discovery Article #70007 (2001)
1Kansas Geological Survey Lawrence, Kansas, U.S.A. ([email protected]; [email protected])
2Independent Petroleum Producer (Deceased)
*Adapted for online presentation of article of same title by same authors in AAPG Studies in Geology No. 47, entitled “Geological Perspectives of GlobalClimate
Change,” now available from AAPG’s online bookstore (http://bookstore.aapg.org).|
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
tMethods of Estimating Ancient Temperature tNatural Variability and Records of Change
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Global
Geologic
processes are not in equilibrium. Geologic processes are one set of
drivers for The
chapters of AAPG Studies in Geology No. 47, Geological Perspectives
of Global One
of the most difficult concepts to communicate to the lay public is the
scale of temperature changes through time compared with Several
general statements are appropriate about natural systems.
Figure 1 Caption (continued): First-order
Figure 1 Caption (continued): Second-order
Figure 1 Caption (continued): Third-order
Figure 1 Caption (continued): Fourth-order
The
sun is the primary source of energy for the We
consider these two effects, solar-system geometry and fundamental
greenhouse conditions, to be first-order Second-order
Temperature variation under this scenario ranges up to 15OC, with major global impacts. Second-order control of global temperature is natural, driven by earth dynamics, and occurs over tens to hundreds of millions of years. For instance, the Cretaceous “greenhouse” condition changed to the modern “icehouse” condition over a period of 60 million years. There appears to be a relationship between the intensity of temperature variation and the length of time over which it occurs. Third-order
temperature drivers (Figure 1) include variability of solar
energy caused by actual luminosity changes and by orbital “wobbles”
of the planet earth (Pekarek, Chapter 1, GPGCC, 2001).
Temperature changes caused by these wobbles are named “Milankovitch
cycles” (the orbital wobbles were first popularized as Variations
in solar energy reaching the earth’s surface modify the In the short time since 1978, direct measurement of total solar irradiance (TSI) by satellites has shown cyclical variations in solar energy of 0.1% in conjunction with the 11-year sunspot cycle. Indirect evidence from the sun and other sunlike stars indicates that TSI has had significantly greater variation as the sun goes through its energy output cycles. Correlations
between The world ocean is vast, and owing to the specific heat of water, it contains vast amounts of thermal energy. Much of that energy is transferred around the earth through ocean currents. Some is transmitted to and from the atmosphere and controls local weather. Ocean currents are driven by wind, the Coriolis effect, and thermohaline circulation (which depends on density differences of waters entering the ocean). Fresh waters are lighter than saline waters, and warm waters are lighter than cold waters. The density of a water mass will determine whether it rises or sinks in the water column. Broecker
(Chapter 4, GPGCC, 2001) suggests that warm events after glacial
events provide low-salinity, thus low-density, meltwaters into the
ocean, which tend to float rather than sink in areas where sinking (downwelling)
normally takes place. This action interferes with total normal oceanic
circulation; for instance, the Gulf Stream may be diverted eastward by
meltwaters from the North American arctic, depriving England and
northern Europe of heat now moderating their Broecker
postulates that this process would become effective around the time that
atmospheric carbon-dioxide concentrations reach about 750 parts per
million (ppm), or about twice ambient. He believes that such
concentrations might be reached by 2100. If this is a valid cause and
effect, then at some time in the future, assuming that the current
interglacial stage continues to full melting of the Arctic Ocean,
Broeker expects such dramatic A
large number of smaller-scale geological The
recent scientific literature is crowded with examples of short-term or
moderate- to low- intensity, fourth-order Mackenzie et al. in Chapter 3 have modeled the cycles of carbon, nitrogen, phosphorus, and sulfur with the purpose of extracting human contribution to those cycles over the last 300 years. Their conclusions are that fossil-fuel emissions, land-use changes, agricultural fertilization of croplands, and organic sewage discharges to aquatic systems, all coupled with a slight temperature rise, have disturbed the carbon cycle. Land-use changes affect the uptake or release of carbon. Deforestation of Russia and the tropics may result in weakening of the terrestrial carbon sink in the future. Reduction of the thermohaline current transport of CO2 into the deep world ocean could be a result of increased global temperature, and the increased temperature could then be further increased because of the reduction in sequestration of CO2 in the deep ocean. In addition, such a change in the intensity of the thermohaline circulation could increase the ability of coastal marine waters to store atmospheric CO2. Mackenzie et al. have modeled the effects of the proposed Kyoto protocol on future carbon-dioxide (CO2) concentrations. Despite a reduction in emissions of CO2 in their model, concentrations of CO2 would continue to build because of the continuous emissions of fossil-fuel and land-use CO2 to the atmosphere, albeit at reduced rates for the former, complex interactions, and a sluggish response of the system to the reduction in emissions. This would be in part due to continued rise of CO2 in the atmosphere owing to land-use changes and to the fact that CO2 has an approximate 10-year residence time in the atmosphere. Mackenzie et al. suggest that the Kyoto approach might be useful in reducing the rate of increase of future atmospheric CO2 concentrations, but only if the physical and biogeochemical mechanisms of redistribution of CO2 among the atmosphere, land, and ocean do not significantly change from the present. Other effects that may occur include reduced precipitation of carbonate minerals in biotic frameworks and increased transport of organic carbon, nitrogen, and phosphorus into coastal sediments. They suggest that human factors could impact mineral and organic carbon sedimentation, as already seen in lakes in industrialized countries. Methods of estimating ancient temperature The
geologic record contains a large number of clues about former One
possible means to ensure that temperature proxies for past periods of
time are robust and not subject to uncertainties related to erosion,
tectonism, or sedimentation processes is to develop techniques based on
materials that represent well-constrained and continuous time intervals.
Reconstruction of paleoclimatic conditions based on the study of stable
isotopes in ice core materials is one such proxy, and it has evolved
into a well-recognized and powerful methodology. The review paper by
Thompson (Chapter 5, GPGCC, 2001) illustrates how stable isotopic
data are acquired and interpreted, and demonstrates how this technique
has emerged as a climatic indicator. Ice-core materials from mid- to
low-latitude glaciers represent a time span of approximately 25,000
years and provide valuable insight to regional variation in Isotopic data are presented for several ice cores collected from three low-latitude but high-altitude locations of the Tibetian Plateau and from the Andes Mountains of South America. The results show that the Tibetian Plateau area experienced warm climates (like that of today) about 3000 years ago. In the Andes, such conditions existed about 5000 years ago. Thompson suggests that tropical warming, as demonstrated by significant losses of ice mass from low-latitude glaciers, is enhanced by (1) evaporation of oceanic water and (b) the release of latent heat (due to condensation) at higher elevations. He also proposes that water vapor, the most important greenhouse gas on earth, is pumped into the atmosphere at low latitudes. Any increases in CO2 levels may contribute to an increasing global inventory of water vapor and may strongly influence global changes. The technique developed by Nagihara and Wang (Chapter 6, GPGCC, 2001) relies on data from boreholes drilled into the seafloor as a means to determine variation in bottom-water temperature (BWT) over the last few hundred years. The study is based on 18 temperature measurements collected from an ODP (Ocean Drilling Program) site in the Straits of Florida; the water depth at this location is 669 m. Temperature measurements were made at subseafloor depths between 26 and 348 m, and those from the seafloor down to about 100 m show a different temperature trend from those taken at greater depths. The authors use an inversion technique to detect temporal variation of BWT at the ODP site. The variation of BWT is compared with Key West surface air temperatures collected between 1850 and the late 1990s and found to be in good agreement. The air-temperature data show higher values between about 1860 and 1885, a rapid cooling during the late 1880s, and a progressive increase for the first half of the twentieth century. The BWT reconstructed history at this location shows the same relationship. Nagihara and Wang use published data for locations off the coasts of Massachusetts and New Jersey to further demonstrate the methodology. The second example involves temperature data collected since 1925 at a water depth of 800 m. These measurements show systematic warming from the late 1920s through the 1970s, and the reconstructed BWT curve shows a similar history. This
technique requires that (1) borehole temperatures are free of drilling
disturbances, (2) a sufficient number of measurements are made over
small vertical depth intervals, and (3) effects of sedimentation,
erosion, and pore fluid movement can be accurately determined. When such
conditions can be satisfied, BWT-reconstructed history curves may become
very powerful tools for assessing global Coralline sponges or sclerosponges live in tropical marine waters but cannot compete with reef-building corals and primarily exist at depths to which light does not greatly penetrate (i.e., below the photic zone). These organisms precipitate calcium-carbonate (CaCO3) growth rings from seawater to form their exoskeleton structure. Hughes and Thayer (Chapter 7, GPGCC, 2001) present evidence that Mg:Ca and Cl:Ca elemental ratios of the precipitated CaCO3 material have potential application for evaluating past seawater temperatures and salinity conditions. In addition, these workers review the literature concerning precipitated CaCO3 in fossil ostracodes, mussels, bivalves, etc., and paleotemperature conditions. A sclerosponge began growing on a submerged marker plate that was attached to a submarine cave wall in July 1989, and it was collected for study nine years later. Chemical analysis of the sectioned specimen was made using energy dispersive spectroscopy (EDS), and elemental ratios were determined at discrete locations across individual growth bands. Temperature and salinity data are known from the specific location where the sponge was growing, and a correlation was developed between them and the measured elemental ratios. The preliminary result was the creation of a curve that provided submonthly temporal resolution and temperature variations on the order of tenths of a degree Centigrade. This technique has potential as a means to evaluate marine paleotemperature and paleo salinity conditions. Because individual sclerosponges can live for centuries, it may be possible to reconstruct high-resolution seawater temperature profiles for the past 2000 years. Such a tool would be quite powerful in helping to understand and quantify past global climatic conditions. In
addition to techniques that may reveal paleoclimate information from
marine settings, some lines of evidence are based exclusively on
terrestrial organisms (Ashworth, Chapter 8, GPGCC, 2001).
Insects, specifically fossil beetles, provide such evidence. The
estimated 1 million to 7 million species of beetles account for
approximately 20% of all species on earth. They are found in almost all
habitats, ranging from high mountain settings to rain forests. Beetles
occupied the interior part of Antarctica until the Neogene, when the
growth of the polar ice sheets resulted in their extinction. The fossil
record indicates that beetle diversity has not increased due to rapidly
changing A
fossil beetle assemblage collected from northern Greenland demonstrates
an unusual level of stasis through approximately 2 million years, even
though the Beetles
are highly mobile insects, and their most apparent response to variation
in The use of fossil biosensors to estimate paleoatmospheric levels of CO2 is an area of active research, and Chapter 9, GPGCC, 2001, by Kurschner et al. is especially interesting due to early results as well as potential applications. The technique is based on the fact that all higher land plants rely on stomata to regulate the exchange of gas between the atmosphere and leaf tissue. Herbarium materials collected during the last 200 years and growth experiments conducted under preindustrial conditions all demonstrate an inverse relationship between stomata development and atmospheric levels of CO2. Elevated levels of CO2 produce fewer stomata than do decreased levels. SI (Stomatal Index) values for birch trees dated (by radiocarbon) at 10,070 years are in the 12 to 14 range and correspond to CO2 levels of approximately 240 to 280 parts per million, volume (ppmv). Birch trees that are 9370 years old have SI values of 6 to 8 and indicate CO2 concentrations of 330-360 ppmv. Thus, these findings indicate an 80-90 ppmv variation in naturally occurring CO2 levels over a 700-year period. Additionally, SI data suggest a dramatic change of 65 ppmv CO2 levels in less than a century. Several lines of evidence indicate that early to middle Miocene time was one of the warmest periods of the entire Cenozoic. Kurschner et al. studied exceptionally well preserved fossil angiosperm materials of middle Eocene age and found that SI values were elevated. By extrapolation of SI data, the authors offer an estimate of 450-500 ppmv for the CO2 level of the middle Eocene atmosphere. Based on these results and those obtained over the last few years, it appears that plant biosensor technology has good potential as a proxy for assessing paleoatmospheric CO2 concentration levels. Natural variability and records of change Interpretation
of geological evidence for In
a previously published article, Bluemle et al. (1999; also Chapter 10, GPGCC,
2001) have recreated the Pleistocene Bluemle
et al. present several lessons. First, over the last 60 million years,
in central Europe, temperature has dropped by more than 20OC
(their figure 1). In relatively recent times, the Medieval
The
second lesson from the paper by Bluemle et al. involves the range of
variation of temperature. The variability of temperature has been
constant, especially for those processes considered in the third-order
range. Temperature changes such as those discussed above have been
regular, although not clearly cyclical, parts of the current
interglacial stage. That temperature varies continuously and at all
scales is apparent from any cursory or detailed examination of Third,
none of these temperature changes is human induced, suggesting that the
fourth-order changes that might be induced by human activities may be
transitory and of relatively low importance. However, there is a major
point about General
circulation models (GCMs) are the basis for much discussion of the role
of CO2 in the atmosphere and as a These
are important points. That the current rate of temperature increase is
not unusual, despite the human-induced addition of CO2,
implies that it is not possible to detect a human imprint on earth
temperatures. But the fact that the temperature has been declining
slowly since the end of the Little Dryas, 10,000 years ago, implies that
the agricultural base of human society may be threatened by continued
cooling. Human population has dramatically increased since the beginning
of the industrial revolution, corresponding to major advances in
agricultural output and the advent of modern medicine. Technology has
permitted population growth. If the Geological
interpretations are four-dimensional, that is, they consider time as
well as space. Many lay people wrongly assume that sea-level effects are
unidirectional, whereas they are actually relative (that is, land
elevation changes as well as actual sea level). Harff et al. in Chapter
12, GPGCC, 2001, demonstrate that the rise and fall of sea level
in the Baltic Sea region is a function of This
means the area south of the Baltic Sea, a densely populated area on a
low-lying coastal plain, is faced with climatically controlled
retreating shorelines. Harff et al. lay the groundwork for development
of strategies for the protection of subsiding coastal areas. The pattern
and high rate of sea-level change in the Baltic qualify the Baltic Sea
to serve as a “model ocean” for studies that reveal the effects of
natural geological processes, including Parenthetically,
measurement of sea level is very difficult because of the roughness of
the water surface, continually varying tides, slow tectonic movement of
the land surface, land subsidence by water withdrawal, and wind effects.
Continual improvement in techniques for measurement of actual sea level
are critical to predicting the effects of One
issue that receives popular attention and is of very personal interest
to those who live on low-relief coral atolls and islands in the Pacific
is the rate and magnitude of sea-level changes to be expected under
various Using new diving technologies and accessing resource exploration seismic and drilling data as well as research drilling data, Shinn has documented lowstand beaches and coral reefs whose elevations are approximately 80 m below present sea level. However, his figure 1 indicates that the last lowstand was approximately 130 m below standard. Thus a minimum range for sea-level change through a full glacial cycle is 86 m in tropical areas where glacial rebound is not significant. Of interest is that the sea-level record (Shinn’s figure 1) approximates the “sawtooth” effect seen in the temperature records, that is, sharp warming episodes that gradually cool. The causes of this sawtooth effect are still being debated, but for glacial and interglacial episodes it may be the result of polar ocean freezing and cutting off moisture to feed continental glaciers, with rapid warming and sea-level rise as a consequence, or thermohaline circulation changes as postulated by Broecker, Shinn, and others (Broecker, Chapter 4, GPGCC, 2001; Shinn, Chapter 13, GPGCC, 2001). Whether
human-induced CO2 is a significant factor in Sequestration is the common term used to describe methods for placing CO2 where it cannot affect atmospheric concentrations. This book contains papers that describe two possible methods. The first, an original piece of scientific research into a generally difficult problem of the origin of lime mud in the ocean (Yates and Robbins, Chapter 14, GPGCC, 2001), documents that microbial activity in the ocean may be responsible for generation of lime mud. The chemistry of organic catalysis takes up CO2 and thus provides a possible method to sequester CO2 through sedimentation in the shallow ocean. The details of the original research are somewhat technical and may be difficult for the lay scientist to follow, but their summary provides the reader with an overview of the potential for a new geological sequestration process. Biologic catalysis can remove CO2 from water while producing lime mud, either in sheaths around the microbe or on (or near) the surfaces of cells without sheaths. Both processes result in direct precipitation owing to the microchemical conditions surrounding the microbe. This process sheds light on the controversial question of production of large amounts of lime mud that cannot be accounted for by controlled biologic precipitation or by skeletal abrasion and disintegration. The second paper (Bachu, Chapter 15, GPGCC, 2001) addresses use of subsurface (underground) sedimentary rocks as a long-term (or “permanent”) host for anthropogenic CO2 as one of several possible means to dispose of unwanted CO2. The physical state of CO2 changes phase, depending on temperature and pressure conditions. This permits the gas to be a liquid or hydrate solid in the deep ocean, but the technologies to handle large volumes of CO2 in this manner are not yet developed, nor are the long-term effects of ocean disposal well understood. On the other hand, the petroleum industry is skilled at subsurface geological exploration and development, and can access potential geological disposal sites with economical technology used in the production of oil and gas. Defining the best potential conditions for geologic disposal of CO2 means extensive geological analysis of buried rocks and careful interpretation of the geological history of confining structures. Bachu argues that CO2 can be sequestered in geologic traps as a gas, a liquid, or in a supercritical state, similar to the natural trapping of hydrocarbons (oil and gas), if the proper conditions exist. Geologic trapping, hydrodynamic trapping, solubility trapping, mineral trapping, and cavity trapping are all geologic possibilities. Trapping in geologic media, whatever the method, may be the easiest and cheapest method to permanently dispose of anthropogenic CO2. Bachu treats the subject in detail, identifying the criteria that should be used to find and effectively use geologic media for sequestration. Interestingly, some of the CO2 can be used to produce more petroleum because of the miscibility of CO2 with oils and coalbed methane, perhaps forming a closed loop of energy production that sequesters as much CO2 as is emitted. A current research project of the Kansas Geological Survey and the U.S. Department of Energy is addressing this opportunity. Using
statistical methods, Kotov (Chapter 16, GPGCC, 2001) has examined
the Greenland ice-core record for patterns that can be projected into
the future. Using the geological past to understand the present is part
of every geologist’s training, as is the reverse. Statistical analysis
of past Study
of the past permits Kotov to predict the future. The present Corroboration
of this prediction appears in a very recent related paper (Keeling and
Whorf, 2000) about 1800-year tidal cycles that may be responsible for
the twelfth-century It is usually significant when two completely different methodologies arrive at a similar conclusion independently of each other, and thus we offer these observations to assist readers in making up their own minds on this matter. The
paper by Idso (Chapter 17, GPGCC, 2001) is one of two reprinted
in that volume by permission of the original publishers. It represents
an unusual set of observations, measurements, and interpretations
carried out while the author was studying meteorological processes over
a two-decade period, wherein he and his colleagues quantified the
climatic consequences of several naturally occurring atmospheric
phenomena: variations in atmospheric dust content, cyclical patterns of
solar radiation receipt, the greenhouse effect of water vapor over the
desert Southwest of the United States, etc. This paper, originally
published in Based
on measurements resulting from eight types of “natural experiments,”
Idso deduced that raising the air’s CO2 concentration from
300 to 600 ppm should result in an increase in mean surface air
temperature of no more than 0.4OC. This estimate is only
about one-tenth to one-third of the temperature increase typically
projected by numerical simulation results obtained from general
circulation models used by Idso also provides a summary of relative temperature changes over the last millennium. He points out that there were two episodes, each of several hundred years’ duration, during which temperatures may have been somewhat higher (the Little Climatic Optimum, or, Medieval Warm Event) and lower (the Little Ice Age) than they are today, and that CO2 levels, deduced from ice cores, showed no changes over those periods. Of
particular interest in this paper are Idso’s descriptions of
mechanisms that might enhance the overall cooling properties of the
earth if global temperatures were to increase slightly. These negative
feedbacks include the likelihood that a 10% increase in earth’s low
cloud cover would completely cancel the warming predicted to result from
a doubling of the air’s CO2 content, plus the fact that a
warmer and CO2-enriched world would produce clouds with an
increased liquid water content and increased levels of cloud
condensation nuclei (which allow clouds to last longer and cool the
earth longer). And in what may be considered a bit of natural irony,
some of these meteorological phenomena can be triggered by elevated
levels of CO2 alone, without an accompanying temperature
increase. Finally, Idso indicates his skepticism about the ability of
general circulation models of the atmosphere to correctly predict how
opposing climatic forces will respond to increased levels of atmospheric
CO2, and he expresses serious reservations about the use of
such models to develop national and international energy policies
related to potential The
final paper in this volume is a philosophic view of the issue of Geologists
know the earth is a single dynamic system, billions of years old, that
is not in equilibrium. A flat, featureless, and uninteresting earth
would be the result of equilibrium. Because change is constant,
inevitable, and interesting, humankind must embrace change rather than
fear it. Adaptation to the changes that continually occur on our planet
requires flexibility, planning, and acceptance of the earth-system
constraints. Political processes cannot change earth dynamics. Changes
that do take place must be placed in context of their real effects. And
finally, a major and recurring theme of this volume bears repeating once
more.
exclusive
of Geological
Perspectives of Global Berner, R., 1994, 3Geocarb IIA Revised model of atmospheric CO2 over Phanerozoic time: American Journal of Science, v. 291, p. 56-91. Berger,
A. L., J. Imbrie, J. D. Hays, G. J. Kukla, and B. Salzman, eds., 1984,
Milankovitch and Broecker,
Wallace S., 1997, Thermohaline circulation, the Achilles heel of our
Broeker, Wallace S., 1999, What If the Conveyor Were to Shut Down? Reflections on a Possible Outcome of the Great Global Experiment: GSA Today, v. 9, No. 1, p. 1-4. Crowell,
John C., 1999, Pre-Mesozoic ice ages: Their bearing on understanding the
Ewing, M., and W. L. Donn, 1956, A theory of ice ages: Science, v. 123, n. 3207, 15 June 1956, p. 1061-1066. Fischer,
A. G., 1982, Long-term Fitzpatrick,
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D. V., and K. H. Schatten, 1997, The Role of the Sun in Katz, M. E, D. K. Pak, G. R. Dickens, and K. G. Miller, 1999, The Source and Fate of Massive Carbon Input During the Latest Paleocene Thermal Maximum: Science, v. 286, p. 1531-1533. Keeling, C. D., and T. P. Whorf, 1997, Possible forcing of global temperature by the oceanic tides: Proceedings of the National Academy of Science, v. 94, p. 8321. Keeling,
Charles D., and T. P. Whorf, 2000, The 1,800 year oceanic tidal cycle: A
possible cause of rapid Lamb,
H. H., 1995, Lang, C., M. Leuenberger, J. Schwander, and S. Johnson, 1999, 16OC rapid temperature variation in central Greenland 70,000 years ago: Science, v. 286, p. 934-937. Moore, Peter D., Bill Chaloner, and Philip Stott, 1996, Global environmental change: Blackwell Science, Oxford, England, 244 p. NASA Web site: http://www.nasa.gov/today/index.htm. Parrish,
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Geological
Perspectives of Global 2001 Chapter
1. Solar forcing of earth’s Chapter
2. Distribution of oceans and continents: a geological constraint on
global Chapter 3. Recent past and future of global carbon cycle, by Fred T. Mackenzie, A. Lerman, and L.M.B. Ver. Chapter 4. Are we headed for a thermohaline catastrophe?, by Wallace S. Broecker. Chapter 5. Stable isotopes and their relationship to temperature as recorded in low-latitude ice cores, by Lonnie G. Thompson. Chapter 6. Century-scale variation of seafloor temperatures inferred from offshore borehole geothermal data, by Seiichi Nagihara and Kelin Wang. Chapter 7. Sclerosponges: potential high-resolution recorders of marine paleotemperatures, by Gary B. Hughes and Charles W. Thayer. Chapter
8. Perspectives on Quaternary beetles and Chapter 9. Using fossil leaves for the reconstruction of Cenozoic paleoatmospheric CO2 concentrations, by Wolfram M. Kürschner, Friederike Wagner, David L. Dilcher, and Henk Visscher. Chapter
10. Rate and magnitude of past global Chapter 11. The search for patterns in ice-core temperature curves, by John C. Davis and Geoffrey C. Bohling. Chapter 12. Sea-level change in the Baltic Sea: interrelation of climatic and geological processes, by Jan Harff, Alexander Frischbutter, Reinhard Lampe, and Michael Meyer. Chapter 13. Coral reefs and shoreline dipsticks, by E.A. Shinn. Chapter
14. Microbial lime-mud production and its relation to Chapter 15. Geological sequestration of anthropogenic carbon dioxide: applicability and current issues, by Stefan Bachu. Chapter
16. Near-term Chapter
17. Carbon-dioxide-induced global warming: a skeptic’s view of potential
Chapter
18. Potential impact and effects of |
Figure
1. 