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5
Implementing a Deep-Time
Climate Research Agenda
The present state of scientific knowledge regarding the deep-time
record of climate change, summarized in previous chapters, highlights
the insights that have been gleaned from studies of past warmings and
major climate transitions, including some that are analogues for antici -
pated future climates. This research status outline provides an indication
of the most important enduring issues that will require further research
and points to the potential for dramatic scientific discovery in the largely
untapped deep-time record. This chapter presents a scientific research
agenda designed both to answer the series of major questions posed in
Chapter 1 regarding the impact of the projected rise in atmospheric pCO2
and to provide a more refined understanding of the important processes—
uniquely present in the deep-time geological record—that will drive
the Earth system as it transitions to a warmer world. The chapter also
describes the research tools and community effort that will be required
to implement this research agenda and provides recommendations for
an education and outreach strategy designed to broaden scientific and
general community understanding of the contribution that can be derived
only from the deep-time record. Finally, the committee stresses the need
to bolster existing mechanisms, and design new mechanisms, for bringing
together interdisciplinary collaborative scientific teams from diverse fields
to focus on the insights that can be gleaned from the deep-time geological
record and to ensure the maximum integration and sharing of the diverse
databases that will result from this research.
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ELEMENTS OF A HIGH-PRIORITY DEEP-TIME CLIMATE
RESEARCH AGENDA
The workshop hosted by the committee provided a wealth of informa-
tion concerning the existing scientific status of deep-time climate research,
as well as a very broad range of topics that the community suggested as
research foci for an improved understanding of Earth system processes
during the transition to a warmer world. The committee assessed these
topics and their potential to transform scientific understanding, and iden -
tified the following six elements of a deep-time research agenda as having
the highest priority to address enduring scientific issues and produce
exciting and critically important results over the next decade or longer.
Improved Understanding of Climate Sensitivity and
CO2-Climate Coupling
Existing data indicate that climate forcing resulting from increased
CO2 will, by the end of this century, rival that experienced during past
greenhouse periods prior to the onset of the current glacial state. The
paleoclimate record, which captures the climate response to a full range
of levels of radiative forcing, can uniquely contribute to a better under-
standing of how climate feedbacks—both long and short term—and the
amplification of climate change have varied with changes in atmospheric
CO2 and other greenhouse gases. In the context of the large uncertainty
in estimates of climate sensitivity described in Chapters 1 and 2, a high
research priority for deep-time paleoclimatology is the determination of
equilibrium climate sensitivity on multiple timescales, particularly during
periods of greenhouse gas forcing comparable to that anticipated within
and beyond this century if emissions are not reduced. Existing records
of past warm periods already indicate climate sensitivity well above the
estimated short-term range and show that the future temperature increase
will most likely be amplified once the longer-term feedbacks that have not
operated on human timescales (decades to centuries) during Earth’s cur-
rent icehouse become relevant under warmer conditions.
Further mining of the deep-time geological archive will require
focused efforts to improve the accuracy and precision of existing proxies
for past atmospheric pCO2 and surface air and ocean temperatures, and
to develop new proxies for other paleo-greenhouse and non-greenhouse
gases and aerosols. Data using new and existing proxies could then be syn-
thesized to develop an authoritative global temperature and atmospheric
pCO2 history—at various resolutions—for the full span of Earth’s history.
Improved constraints on levels of radiative forcing and equilibrium climate
sensitivity are needed for past warm periods and major climate transitions.
In addition, further study of intervals of possible CO2-climate decoupling
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(e.g., mid-Miocene, Late Jurassic, Early Cretaceous) will require careful
integration of paleoatmospheric CO2 and paleotemperature time series
with improved temporal resolution, precision, and accuracy, as well as
data-model comparisons to critically evaluate the veracity of these appar-
ent mismatches. With these improved data, a hierarchy of models can be
used to test various forcing mechanisms (e.g., non-CO2 greenhouse gases,
solar, aerosols) to determine how well mechanisms other than CO2 can
explain anomalously warm and cold periods and to critically evaluate the
climate processes and feedbacks that led to particular climate responses
characteristic of greenhouse gas-forced climate changes in the past.
Climate Dynamics of Hot Tropics and Warm Poles
Paleoclimate observations provide a conundrum that must be resolved
to understand the climate system—the evidence that past temperatures in
the tropics and polar regions were periodically much hotter than today.
How can the Earth maintain tropical temperatures approaching 40°C, or
how can polar temperatures remain above freezing year-round? Yet there
is very strong evidence for both conditions during past warm periods.
The deep-time paleoclimate evidence suggests that the mechanisms and
feedbacks in the modern icehouse climate system that have controlled
tropical temperatures and a high pole-to-equator thermal gradient may
not apply straightforwardly in warmer worlds. Moreover, the funda-
mental mismatch between climate model outputs, modern observations,
and paleoclimate proxy records discussed in Chapter 2 highlight the
degree to which science’s current understanding of how tropical and
higher-latitude temperatures respond to increased CO2 forcing remains
limited. An improved understanding of these processes, which may drive
significant changes in surface temperatures in a future warmer world,
is imperative given the potential dire effects of higher temperatures on
tropical ecosystems and the domino effect of polar warming on ice sheet
stability, the stability of permafrost (which carries a large load of green -
house gases), and regional climates through atmospheric teleconnections
with the tropics and/or polar regions.
Accomplishing this goal requires that the range of deep-time obser-
vational data be expanded to include latitudinal transects that span the
tropics through mid- to high-latitude regions for targeted intervals of
Earth history. Improved constraints on the meridional thermal structure
of warm worlds will require increased chronological constraints and more
spatially resolved proxy time series than currently exist. New theoretical
and modeling approaches are also required to develop a comprehensive
understanding of the limits of tropical and polar climate stability, and an
understanding of how a weaker thermal gradient is established and main-
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tained in warmer climate regimes. Global climate models (GCMs) offer
an astounding array of diagnostics for assessing atmospheric dynamics
and teleconnections, but these diagnostics need to be employed far more
commonly in analyses of paleoclimate simulations, requiring deeper and
“real-time” collaborations between the “observationists” and the atmo -
spheric dynamicists. The documented ability to successfully model condi-
tions comparable to those anticipated in the future will provide a test of
the efficacy of climate model projections for continued global warming.
Sea Level and Ice Sheet Stability in a Warm World
Large uncertainties in the theoretical understanding of ice sheet
dynamics and associated feedbacks currently hamper the ability to predict
how the ice sheets currently in the Earth’s polar regions, and sea level, will
respond to continued climate forcing. For example, paleoclimate studies
of intervals within the current icehouse document variability in ice sheet
extent that cannot be reproduced by state-of-the-art coupled climate-ice
sheet models. Moreover, studies of past warm periods indicate that equilib-
rium sea level in response to current warming may be substantially higher
than model projections indicate due to the influence of dynamic processes
that have not been operative in the recent past. Efforts to address these
issues will have to focus on past periods of ice sheet collapse that accompa-
nied transitions from icehouse to greenhouse conditions, to provide context
and understanding of the “worst-case” forecasts for the future.
Future studies that probe deeper into Earth history should focus on
periods that have the potential to reveal critical threshold levels associ -
ated with ice sheet collapse and to elucidate the dynamic processes and
feedbacks that have led to deglaciation in the past but are not captured
by paleoclimate records of the past few million years. An integral com -
ponent of such studies should be a focus on improving science’s ability
to deconvolve the temperature and seawater signals recorded in biogenic
marine proxies, including refinement of existing paleotemperature proxies
and the development of new geochemical and biomarker proxies. Model -
ing the distribution of ice in warm worlds will need to expand beyond the
intermediate-complexity models that currently include this component in
order to involve the coupling of land ice component models to complex
GCMs and include full interaction with the atmospheric hydrological
cycle.
Understanding the Hydrology of a Hot World
Studies of past climates and climate models strongly suggest that
the greatest impact of continued CO2 forcing will be regional climate
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changes, with ensuing modifications to the quantity and quality of water
resources—particularly in drought-prone regions—and impacts on eco-
system dynamics (Lunt et al., 2008; Haywood et al., 2009; Shukla et al.,
2009). Because of the sensitivity of climate to small changes in high-latitude
and tropical temperatures, an improved understanding of the hydro-
logical cycle during periods of increased radiative forcing—comparable to
those projected for the future—is imperative. Because of the potential for
large feedbacks to the climate system, this in turn requires an improved
understanding of the interaction between the global hydrological and
carbon cycles over a full spectrum of CO2 levels and climate conditions.
The deep-time record uniquely archives the physical and geochemical
expressions of the carbon and water cycle dynamics that operated during
past warm periods, including the response of low-latitude precipitation
to high-latitude unipolar glaciation or ice-free conditions (e.g., Floegel
and Wagner, 2006; Poulsen et al., 2007a,b; Ufnar et al., 2008), the stabil -
ity of continental carbon reservoirs (soils, wetlands, tundra, permafrost)
to changing regional climates, and the impacts on—and response of—
ecosystems to such changes.
These research objectives require the development of marine-terrestrial
transects with spatially resolved proxy records at high temporal resolu-
tions and precisions. In particular, paleoterrestrial reconstructions have
long been plagued by sparse and discontinuous outcrop, stratigraphically
incomplete successions, and poor chronological constraints. The optimum
approach is thus to integrate chronostratigraphically well-constrained
marine records with contemporaneous terrestrial records through integra-
tion of radiometric, biostratigraphic, and/or magnetostratigraphic data.
The implementation of this objective will require transect-focused ocean
and continental drilling.
Efforts to improve existing proxies, to develop new proxies, and to
develop multiproxy time series in order to provide quantitative estimates
of paleoprecipitation, paleoseasonality, paleohumidity, and paleosoil
conditions (including paleoproductivity) are a critical component of this
research, in particular where the level of precision—and thus the degree of
uncertainty in inferred climate parameter estimates—can be significantly
reduced. Proxy improvement efforts should include strategies for better
constraining the paleogeographic setting of proxy records, including lati-
tude and altitude or bathymetry.
Understanding Tipping Points and Abrupt Transitions
to a Warmer World
Studies of past climates and climate models show that Earth’s cli-
mate system does not respond linearly to gradual CO2 forcing, but rather
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IMPLEMENTING A DEEP-TIME CLIMATE RESEARCH AGENDA
responds by abrupt change as it is driven across climatic thresholds.
Modern climate is changing very rapidly, and there is a possibility that
Earth will soon pass thresholds that will lead to even more rapid changes
in Earth’s environments. It is possible that such thresholds could involve
transition into a new climate state that cannot return to pre-CO2 forcing
conditions if the prior conditions are reestablished. Thus the proximity of
Earth to such a ‘tipping point’ is a critical question. The answer does not
reside in the more recent paleoclimate record, but rather is to be found in
the dynamics of past transient events where the climate system crossed
critical thresholds into climate states more representative of where Earth’s
climate may be heading. Because of their proven potential for capturing the
dynamics of past abrupt changes, intervals of rapid (millennia or less) cli -
mate transitions in the geological record—including past hyperthermals—
should be the focus of future fully integrated paleoclimate, paleoecologic,
and modeling collaborations. Key insights to be gleaned from such studies
include an improved understanding of how various components of the
climate system responded to such abrupt transitions, in particular during
times when the rates of change were sufficiently large to imperil biotic
diversity. There is also a need to understand where to expect thresholds
and feedbacks in the climate system—especially in warm worlds and past
icehouse-to-greenhouse transitions. Moreover, targeting such intervals for
more detailed investigation is a critical requirement for constraining how
long any such climate change might persist.
Key requirements for an improved understanding of abrupt climate
change are better dynamic models and datasets to resolve the behavior of
the environment in transition. On the data side, substantially improved
spatial (subkilometers to tens of kilometers over large geographic regions)
and temporal (subcentennial scale) resolution of datasets from Earth’s past
are required to illustrate the behavior of environmental systems in rapid
transition. These include both examples of transition into fundamentally
new climate states and examples of transient climate states that ultimately
returned to near preperturbation conditions (e.g., the Paleocene-Eocene
Thermal Maximum [PETM]). To be most effective, temporal resolution on
the level of centuries or less is needed to identify and understand climate
and ecosystem changes at rates relevant to human society.
Current predictions of the duration of future greenhouse conditions
are based on simplified models of the climate system and carbon cycle,
constrained by limited observations of their behavior during analogous
times in Earth history. A more convincing answer to the central question
of “how long” requires more sophisticated and comprehensive models,
and it will be possible to have confidence in the models only if they can be
evaluated against observations. Intermediate-complexity models that are
capable of running continuous simulations for the 10,000 to 100,000-year
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duration of these events are needed, and such models need to treat the
ocean and atmosphere as an open system as the basis for spatial and
temporal predictions that can be directly compared with observational
data of similar temporal resolution. Specifically, it is important that the
models calculate variables that are similar to those measured in the field
or calculated using proxy methods, so that direct comparisons between
paleoecosystem proxies and model results are possible—for example, the
inclusion of oxygen and carbon isotopes as tracers in both atmosphere
and ocean models or, in the case of models of intermediate complexity,
the inclusion of sediment transport modules. The historical record and
even the broad expanse of the Pleistocene climate record contain nothing
comparable to the anticipated outcomes following the burning of all fossil
fuel resources, and thus cannot be considered appropriate analogues from
which to refine an understanding of the climate and ecosystem changes
that continued warming will cause.
Understanding Ecosystem Thresholds and Resilience
in a Warming World
Both ecosystems and human society are highly sensitive to abrupt
shifts in climate because such shifts may exceed organism tolerances and
consequently have major effects on biotic diversity as well as human
investments and societal stability. Modeling future biodiversity losses
and biosphere-climate feedbacks, however, is inherently difficult because
of nonlinear interactions and the existence of both positive and negative
feedbacks that add complexity to the system and increase the uncertainty
of the net response to climatic forcing. How rapidly biological and physi-
cal systems can adjust to abrupt climate change is a fundamental question
accompanying present-day global warming. An important tool to address
this question is to describe and understand the outcome of equivalent
“natural experiments” in the deep-time geological record, in particular
where the magnitude and/or rates of change in the global climate system
were sufficiently large to threaten the viability and diversity of species,
leading at times to mass extinctions. The paleontological record of the past
few million years does not provide such an archive because it does not
record catastrophic-scale climate and ecological events.
The deep-time record of past biotic turnovers and mass extinction
events associated with warm periods (many associated with massive
outgassing of CO2 or methane), transient warmings, and major transi -
tions between climate states offers an undertapped repository from
which unique insights can be obtained regarding patterns of ecosystem
stress, the potential for ecological collapse, and mechanisms of ecosys -
tem recovery. For example, integrated paleoclimate and paleoecology
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studies can uniquely address the fundamental question of how hot the
tropics will become, and how much ocean chemistry will be perturbed,
under additional CO2 radiative forcing. This is a critical issue because
such changes may have dire effects on tropical ecosystems, with the
potential for severe declines in diversity over large areas. For example,
studies of past greenhouse gas-forced transient warmings provide the
only analogue of the future potential for ocean acidification and its effect
on calcifying organisms. The penultimate deglaciation of the Late Paleo -
zoic Ice Age is the only archive recording how tropical floral ecosystems
might respond to climate change associated with an epic deglaciation.
The issue of how Arctic ecosystems will respond if sea ice disappears
permanently and/or the Greenland ice sheet retreats significantly can
only be addressed through studies of past warm periods, such as the
mid to late Cretaceous and the early Cenozoic, when the Arctic was
ice-free and supported lush temperate rainforests and associated fauna.
As with the other elements of a deep-time research agenda, improved
dynamic models, more spatially and temporally resolved paleoclimate
and paleontological datasets with high precision and chronological
constraint, and data-model comparisons, are all critical components of
future research efforts to better understand ecosystem processes and the
dynamic interactions with changing climates.
STRATEGIES AND TOOLS TO IMPLEMENT
THE RESEARCH AGENDA
The deep-time paleoclimate research agenda described above will
require four key infrastructure and analytical elements, each of which is
described in greater detail below:
1. Development and evaluation of new mineral and organic proxies
and refinement of existing methods through calibration studies in modern
systems and laboratories. Such efforts must be coupled with the develop -
ment of multiproxy paleoclimate time series that are spatially resolved, of
high temporal resolution, and of improved precision and accuracy.
2. Substantially increased investment in scientific continental drill-
ing and continued support for scientific ocean drilling. Only recovery
of high-quality cores can provide the requisite sample resolution and
preservational quality to develop multiproxy archives for key paleocli -
mate targets across terrestrial-paralic-marine transects and latitudinal or
longitudinal transects. The International Continental Drilling Program
has a strong record of drilling a range of scientific objectives, including
paleoclimate targets, but in contrast to strong support for this program by
the European science community and other countries, U.S. support has
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been at relatively low levels. Also, although U.S. leadership in scientific
ocean drilling has been a major factor in the present understanding of
past climates and climate-ocean linkages, recent funding cutbacks have
jeopardized the potential for the oceanic component of the deep-time
paleoclimate agenda described here to be realized.
3. Development of a new generation of models for paleoclimate
studies, capable of focusing on past warm worlds and on extreme and/or
abrupt climate events. Such new models will require unprecedented spa-
tial resolution and additional capabilities to permit innovative data-model
and model-model intercomparisons that are more consistent with Inter-
governmental Program on Climate Change (IPCC) style assessments. This
will maximize the potential for paleoclimate modeling studies to inform
climate model development in general and for future climate simulations.
4. Substantially increased programmatic and financial support
for the cultural and technological infrastructure that is needed for a
“sea change” in the deep-time research culture—a shift away from
single principal investigator (PI) or small collaborative projects to fully
interdisciplinary synergistic research teams. Support for such research
efforts will require a serious and committed investment in human and
financial resources to establish large-scale, integrative programs for
analyzing and archiving stratigraphic, sedimentological, geochemi -
cal, and paleontological datasets. A key ingredient will be the forma -
tion of deep-time “observatories” to unify researchers of disparate but
complementary expertise to target specific processes or intervals of time,
dedicated software engineering support and computational resources for
model development and deep-time climate simulations, and professional
development workshops and summer institutes for student training and
early-career scientists.
5. An interdisciplinary collaboration “infrastructure” to foster
broad-based collaborations of observation-based scientists and modelers
for team-based studies of important paleoclimate time slices, incorporat-
ing climate and geochemical models; capabilities for the development,
calibration, and testing of highly precise and accurate paleoclimate
proxies; and the continued development of digital databases to store
proxy data and facilitate multiproxy and record comparisons across all
spatial and temporal scales. Making the transition from single researcher
or small-group research efforts to a much broader-based interdisciplinary
collaboration will be only possible through a modification of scientific
research culture and will require substantially increased programmatic
and financial support.
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Improved Proxies and Multiproxy Records
One of the most important areas of paleoclimatology research is the
need for improved constraints on past levels of radiative forcing and
better estimates of long-term equilibrium climate sensitivity for previous
warm periods and major climate transitions. Estimates of pCO2 (through
“paleobarometer” proxies) beyond the ice core records of the past 800,000
years, however, are inherently constrained by sizable uncertainties and
the limits of sensitivity of marine or terrestrial proxies and/or of the
numerical models of the long-term carbon cycle on which they are based.
Furthermore, no proxies exist for greenhouse gases other than CO2, such
as methane. Similarly, the precision and accuracy of existing organic and
mineral paleotemperature proxies are compromised by their calibrations
solely to extant analogues and by incompletely understood biological
and environmental controls on stable isotope and trace metal incorpo-
ration into mineral proxies and/or their sensitivity to postdepositional
alteration. In addition, a broader ensemble of proxies for estimating past
terrestrial surface and soil temperatures and seasonality of precipitation
is much needed. Therefore, focused efforts to refine and develop prox-
ies for these parameters are a critical element of an enhanced deep-time
paleoclimatology initiative.
Improving existing and new proxies will require field and laboratory
calibration studies in modern marine and terrestrial systems in order to
increase their accuracy and further quantify and constrain uncertainties
associated with estimates. Expansion of organic fossil-based CO2 (e.g., plant
stomatal indices, alkenones of marine haptophytes) and paleotemperature
(biomarker) proxies to extinct taxa that dominate the deep-time record will
require laboratory microcosm (growth chambers) studies that can evalu-
ate biotic responses and geochemical feedbacks associated with chang -
ing greenhouse gas levels or air-water temperature. For mineral-based
paleobarometers and continental paleotemperature proxies, calibration
studies are needed in modern soil systems over a spectrum of landscapes
and climate regimes in order (1) to better understand the influence of local
climate, regional and soil hydrology, and soil productivity on soil CO2 con-
tents, temperature, and moisture—the input parameters for proxy transfer
functions and pCO2 calculations, and (2) to assess the sensitivity of proxy
pCO2 and temperature estimates to these soil parameters, including their
seasonal variability. The Critical Zone Observatories initiative funded by
the National Science Foundation (NSF) may offer opportunities to integrate
such calibration studies within existing observatories.
Ultimately, comparison studies of plant and mineral proxy estimates
that are characterized by differing sensitivities and uncertainties are
required to test the accuracy, precision, and sensitivity of each of the
proxies. In this broader context, however, several foci require continued
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and/or scaled-up research effort. First, studies of the taxonomic effects
on mineral and organic biotic proxies are needed, as are collaborations
between geochemists and paleobiologists for testing and applying biotic
proxies because of the importance of recognizing and evaluating vital
effects on proxy values. Second, continued development of biomarker
proxies should be a high priority given their high precision and sensitivity
and the fact that they appear to be diagenetically robust. Future efforts,
however, need to include (1) critical evaluation of the potential to extend
various biomarker approaches beyond the temporal range of the taxa
for which they were developed (e.g., the alkenone method using marine
haptophytes; Freeman and Pagani, 2005); and (2) more rigorous assess-
ment of the sources, distribution, and preservation potential of various
biomarkers through the deep-time geological record. Third, further evalu-
ation of the effects of post-depositional alteration on mineral isotopic and
geochemical compositions is needed, and this will require the use of emerg-
ing submicron imaging and analytical technology (e.g., scanning electron
microscopy, nanoscale secondary ion mass spectrometry [Nano-SIMS],
laser ablation inductively coupled plasma mass spectrometry coupled to
the Australia National University’s sample cell). Fourth, increased efforts
for development of emerging paleotemperature proxies that are inde-
pendent of biological effects and water composition are needed (e.g., Mg
isotopes, clumped isotope thermometry). Overall, because of the multi -
disciplinary nature of calibration and assessment studies and the diversity
of natural and man-made laboratories in which they would need to be
carried out, these efforts to improve the precision, accuracy, and array of
paleoclimate proxies will require broad-based collaboration and long-term
monetary and human resource investment.
Ultimately, reconstructions of regional variation in climate parameters
and ecosystem changes will require multiproxy, spatially highly resolved,
and temporally calibrated datasets that can be compared across marine-
paralic-terrestrial and latitudinal-longitudinal gradients as a function of
time. Only such databases will notably advance science’s understand-
ing of the marine-terrestrial dynamics of carbon and water cycling in a
warmer world and their role in regional hydroclimate and ecosystem
variability. Such studies should be undertaken in “real-time” collaboration
with deep-time climate modeling efforts using fully integrated terrestrial
and marine climate parameters. In turn, collaborative observation-climate
model studies are an essential mechanism for refining the interpretive
utility of proxies. Continued development of interactive analytical data -
bases that permit the integration of new proxy data about past climate
parameters and boundary conditions, within an existing rock-based spa -
tial and temporal framework, is critical to facilitate the integration and
comparison of multiple proxy time series along latitudinal-longitudinal
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IMPLEMENTING A DEEP-TIME CLIMATE RESEARCH AGENDA
years) that are well below the duration of important climate perturbations
in Earth history. To date, the U.S. contribution to the development of EMICs
has been through collaboration with European and Canadian colleagues,
and continued and expanded international collaboration—perhaps facili-
tated by the collaboration center proposed below—could yield an EMIC
adapted to evaluate the mechanisms of environmental change in deep time
(e.g., capable of simulating oceanic biogeochemical cycling under anoxic
and euxinic conditions, using relevant paleogeographies). Future model
development efforts could target the incorporation of subsystem models,
such as EMICs within Earth system models.
Strategies for Fostering Focused Deep-Time Scientific Interaction
While the paleoclimate characteristics of past warm worlds and times
of major climate transitions contained in the deep-time geological record
constitute a substantially underdeveloped archive offering considerable
potential for major scientific discoveries, such discoveries are unlikely
to be made through single-PI disciplinary research or small-scale col-
laborative projects. For the full potential of the deep-time paleoclimate
archive to be realized, it is critical to foster broad-based collaborations of
observation-based scientists and climate modelers. Making the transition
from single researcher or small-group research efforts to the broad-based
interdisciplinary collaboration envisioned here will be possible only
through a modification of the scientific research culture and will require
substantially increased programmatic and financial support. The infra-
structure needed to support scientific collaboration, cross-disciplinary
syntheses, widespread and open data exchange, and cross-training of
scientists and students will include, at a minimum, the following:
• The development of natural observatories—perhaps analogous
to the NSF Critical Zone Observatories program—for team-based studies
of important paleoclimate time slices or of landscapes that will permit
the testing, calibration, and development of highly precise and accurate
paleoclimate proxies (e.g., “Deep-Time” Critical Zone Observatory(ies)).
Such deep-time observatories would serve to unify researchers of dispa-
rate but highly complementary expertise by targeting specific processes or
intervals of time (e.g., the DETELON initiative by the paleobiology com -
munity). In order to develop the integrated sets of past-Earth boundary
conditions critical to the success of GCMs—and currently a major limita -
tion of climate modeling efforts—collaborative, cross-disciplinary teams
would have to include software engineers and climate modelers as well
as observational-based scientists with varying disciplinary expertise.
• Analytical support for interdisciplinary research through
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BOX 5.3
Data Sharing in a Digital Age
The rock record serves as the primary long-term archive for many
important physical, chemical, and biological processes, including the
tempo and mode of organic evolution, the causes and consequences of
global climate change, the rates and styles of crustal deformation and
plate tectonics, and the origin and spatial and temporal distribution of
mineral and energy resources. Although there exists a formidable body
of knowledge on the distribution and character of rocks and the proxy
data extracted from them, there is currently no framework for consolidat-
ing these data into a larger and interactive context or for analyzing them
quantitatively across a range of time and spatial scales. Importantly, no
such archive yet exists that can integrate with or accommodate paleo-
climate modeling archives—a fundamental necessity for the proposed
synergistic and interdisciplinary research approach to deep-time paleo-
climatology.
Macrostratigraphy is a novel web-based data-sharing program (Figure 5.4)
that uses gap-bound rock packages compiled separately at multiple geo-
graphic locations as a framework for integrating diverse geological and
paleontological datasets and for analyzing quantitatively disparate data.
Currently, this developing macrostratigraphic database consists minimally
of the ages, thicknesses, lithologies, and nomenclatural hierarchies of
21,252 rock units from 821 geographic locations in North America, 1,168
rock units from 329 locations in New Zealand, and 7,124 lithologic pack-
ages from 132 locations in the deep sea. Macrostrat is fully integrated
with the Paleobiology Database, thus serving as the scaffolding upon
which to build a large-scale, integrative analytical framework for uniting
stratigraphic, sedimentological, geochemical, and paleontological datasets
spanning much of geoscience. Macrostrat has been utilized successfully
to quantitatively analyze a wide range of geological questions, such as
how the relative magnitudes of inorganic and organic carbon burial have
fluctuated on a stage-to-stage basis throughout the Phanerozoic. The re-
sults of this example reveal the dominant influence of physically forced
changes in sedimentation on carbon cycling on relatively short timescales,
with implications for the relative cycling rates of terrestrial versus marine
systems, for understanding the biological evolution of marine and terrestrial
organisms, and for calibrating the link between carbon burial and global
climate change. Ultimately, Macrostrat will provide a user-oriented web
application that will enable participation of researchers widely throughout
the community to facilitate data sharing and integration as well as contin-
ued development of new tools.
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IMPLEMENTING A DEEP-TIME CLIMATE RESEARCH AGENDA
Solid
Earth
Rock
Record
Living
Fluid
Earth
Earth
Sh
an
a
.P
n
E
et
er
sa
nd
Bri
dg
et
D iem
FIGURE 5.4 Logo for the macrostratigraphy database, Macrostrat. See
http://macrostrat.geology.wisc.edu and http://strata.geology.wisc.edu/
mibasin.
SOURCE: Courtesy of Shanan E. Peters, University of Wisconsin, Madison.
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130 UNDERSTANDING EARTH’S DEEP PAST
expanded efforts to develop new facilities (e.g., EARTHTIME geochro-
nology laboratories) and enhanced linkages to existing structures (e.g.,
National Center for Nano-SIMS at the University of Wisconsin). Most
importantly, it is critical that such facilities are made available to all inter-
ested scientific parties—an effort that will require proactive and strategic
planning on the part of the funding agencies involved.
• Increased development efforts for large-scale, integrative analyti-
cal models for analyzing and archiving stratigraphic, sedimentological,
geochemical, and paleontological datasets (see Box 5.3). Any such effort
must incorporate plans to integrate with, or accommodate, paleoclimate
model archives that can be fully integrated with geological, proxy, and
paleontological data.
• To ensure that the collaborative opportunities offered are available
to both researchers and “scientists in training,” and to catalyze the cultural
change in established and developing scientists, a structured mechanism
for cross-disciplinary training of graduate students and early-career, and
established scientists is necessary. Financial resources for professional
development workshops and a summer institute(s) (perhaps on a rotat -
ing basis) in topics such as a modeling primer, overview and challenges
of paleoclimate proxies, chronological techniques—all offered within the
context of deep-time paradigms and unresolved problems—should be a
high priority. Such institutes could easily be designed to incorporate sec -
ondary school teachers, museum specialists, and science journalists (see
discussion in “Education and Outreach—Steps Toward a Broader Com-
munity Understanding of Climates in Deep Time” below).
• An emphasis on “virtual” collaborations would be cost-effective
by removing the need for colocation of researchers, would be more in
line with the comfort that younger researchers demonstrate with virtual
interactions, and—by encouraging the interaction of widely distributed
researchers—would help to emphasize that the issues being addressed
are international in scope. Face-to-face meetings involving participants
in a particular research endeavor would, of course, still be necessary on
occasion, but these could perhaps take the form of annual workshops.
Most importantly, establishment of such a cultural and technologi-
cal infrastructure will require acceptance and endorsement by both the
scientific community and the funding agencies that support deep-time
paleoclimatology and paleobiology-paleoecology studies. Without the
addition of targeted new resources—in addition to existing programmatic
resources—the scientific breakthroughs that can be made by this broad-
based research community will be unlikely to come to fruition.
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EDUCATION AND OUTREACH— STEPS TOWARD A BROADER
COMMUNITY UNDERSTANDING OF CLIMATES IN DEEP TIME
Earth’s deep-time climate history not only provides the context
for scientists seeking to understand the Earth system, it also provides
compelling opportunities for broad public outreach and education as it
addresses details of Earth’s natural long-term climate cycles. To capital -
ize on this opportunity, scientists and science communicators will have
to overcome the challenge that understanding deep-time climate requires
some appreciation of the subtleties of both climate science and geological
time and an appreciation that Earth’s preindustrial or even prehuman
climate sets the baseline from which to evaluate the human contribution
to climate change.
The public discussion regarding climate change and global warming
is complex and fractious, in part reflecting the lack of adequate scientific
literacy among the general public, an active campaign of antiscience dis-
information, and insufficient efforts on the part of the scientific community
to disseminate complex information in an effective manner. Similar things
could be said about the public understanding of geological time, the age
of the Earth, radioisotopic dating, and how scientists determine the age of
events in Earth history. Despite these challenges, Earth’s history is the source
of useful and powerful metaphors and examples that have the potential to
help people understand the significance of climate change in their time.
Challenges and Issues
The deep-time climate research community faces a number of chal-
lenges in bringing its insights to students, teachers, professors, scientific
and media partners, policy makers, and the general public, and the fol-
lowing concepts and approaches are suggested to assist with education
and outreach to convey the concepts and recommendations in this report.
These are presented for each of the target audiences, with the challenges
and issues associated with each audience and suggestions for audience-
specific implementation.
Insights gleaned about Earth’s climate system from the experiments
of past climate extremes contained in the geological record both comple -
ment and expand those derived from climate studies of the more recent
past. The study of deep-time paleoclimate integrates a large number of
scientific disciplines because of the span of geological time, and as such it
is not immediately intuitive to a nonspecialized audience. Although they
are central to the practice and understanding of the science of deep-time
climate, geological time, paleoclimate proxy analysis, and GCMs—with
their attendant disciplinary jargon—have minimal traction with the pub-
lic. Uncertainties in temporal resolution, patchwork spatial resolution, and
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132 UNDERSTANDING EARTH’S DEEP PAST
incompletely calibrated climate proxies present challenges for conveying
complex messages to the general public with sufficient simplification but
without losing accuracy.
Finally, there are the difficulties inherent in any multidisciplinary
field—communication between scientists in different fields is imperfect,
leading to imperfect interpretations that can be propagated to conversa-
tions with policy makers and the public. Successful outreach and education
need to be based on better integration of the scientific disciplines involved
and improved transfer of data and knowledge between the different groups
of scientists. Specifically, the observation and modeling communities need
to improve their interdisciplinary communication, as well as broader
communications with other scientists, to build a better pan-discipline
understanding of what science knows about past climates—only then can
these insights be effectively conveyed to broader audiences. Irrespective of
these challenges, however, extinct animals and plants, ancient worlds, and
natural disasters do resonate with people, and these elements all present
good starting points for broader discussions about past climates
Audience-Specific Strategies and Examples
K-12
For elementary and secondary audiences, it is important to be aware of
age-specific learning styles and state educational standards. Children are
interested in dinosaurs and living animals, and these provide wonderful
opportunities to discuss extinction and ecosystems. Extinct animals provide
a pathway to discuss extinct landscapes and different biomes, and compari-
son of modern tropical, temperate, and polar biomes conveys the message
that different animals live in places that have different weather.
Concepts of time are often challenging, and geological time is par-
ticularly difficult. This is amplified for younger children who are just
beginning to understand the concept of time. The EARTHTIME Initiative 1
has recently created middle school curricula to address this issue, but the
barriers to understanding are significant.
For young students, the excitement of exploring prehistoric worlds is
more compelling and less scary than confronting the fear of global climate
change. The recent Ice Age movies presented a climate change message
in concert with charismatic ice age megafauna, introducing the topic in a
fun, rather than threatening, manner. Children’s love of dinosaurs is, in
part, facilitated by the fact that they are scary but extinct. Climate change,
while more conceptual than dinosaurs, is less threatening when studied
1 See http://www.EARTHTIME.org.
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as history than when presented as a looming threat. As always, creation of
tools for teachers that adhere to state standards will result in more usable
education assets.
For most states, geosciences are concentrated at the upper middle
school level, and there is considerable potential to enhance existing cur-
ricula with deep-time climate science. The enhanced communication
capabilities of the Joides Resolution drillship2 have presented opportunities
for live broadcasts to museums and classrooms. Active scientists should
consider presenting simplified versions of their research and findings
in classrooms, at teacher professional training sessions, and at national
conventions such as the National Science Teachers Association meetings.
For high school audiences, awareness of global warming is high and
rapidly increasing. Despite this, most curricula tend to be focused on the
core sciences of biology, physics, and chemistry, with little opportunity to
integrate the more synthetic earth and atmospheric sciences. Science fairs
are arenas in which high school students can reach beyond the finite dis -
ciplines of their curricula, and students themselves can experience field -
work through programs such as the Jason Project,3 which places students
in the field with the ability to broadcast back to their classrooms. In addi-
tion, a number of NSF-funded projects have generated web-based educa-
tion tools. One such program that deals specifically with GCMs is the
Educational Global Climate Modeling Program,4 a collaboration between
Columbia University and NASA’s Goddard Institute for Space Studies,
which allows web visitors to download and run simple climate models.
High school teachers can accrue very practical knowledge by par-
ticipating in special training projects such as the IODP School of Rock
Workshops,5 which sends teachers to sea on the Joides Resolution drillship
to learn about ocean science and seafloor coring. Museums offer teachers
professional development on a variety of topics, such as the Denver
Museum of Nature and Science Certification Program in Paleontology.6
Inherent in all of these courses is the premise that high school teachers
will be more effective if they have primary field experience.
Colleges and Universities
Colleges and universities provide a host of opportunities for students
to understand deep-time climate topics through courses, fieldtrips, intern-
ships, visiting lectures and talks, and campus action groups. Earth and
2 See http://joidesresolution.org/.
3 See http://www.jason.org.
4 See http://edgcm.columbia.edu.
5 See http://www.iodp-usio.org/Education/SOR.html.
6 See http://www.dmns.org.
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134 UNDERSTANDING EARTH’S DEEP PAST
planetary science departments can expand their ranks of potential majors
by offering courses that combine traditional environmental science with
paleontological and paleoclimatological content.
• Graduate students can expand their skills and knowledge by par-
ticipating in interdisciplinary summer schools such as the Urbino Summer
School of Paleoclimatology,7 which bring together active scientists and
diverse graduate students interested in paleoclimatology and modeling.
• Professional organizations such as the American Association of
Petroleum Geologists and IODP support lecture tours by distinguished
lecturers, and these can focus on paleoclimate themes.
• University and college faculty can improve their ability to com -
municate with the media and general public by specific training (e.g., the
Aldo Leopold Leadership Program8 at Stanford University).
General Public
The general public is barraged with global warming issues in the form
of op-eds, letters to the editor, blogs, popular books, television shows, talk
radio commentary, and newspaper and magazine ads from companies
promoting green products to oil and gas companies discussing pathways
to the future of energy. Despite this media blitz, very few people under-
stand that the Earth’s present climate is anomalously cold relative to the
ice-free world of the Cretaceous to Eocene greenhouse. Nor could the typi-
cal citizen begin to articulate how tree rings, ice cores, and seafloor drilling
relate to climate change. Efforts to explain “how scientists know what they
know” are more likely to be received favorably than are proclamations
about what will happen in the future.
The topic itself has become so polarized that some hosts consider
global warming conversations akin to discussing religion or politics at
the dinner table. To counter this, it makes sense to focus on relevant sci -
ence rather than policy or practice. Efforts that intend to educate rather
than advocate are more likely to be heard and understood by a diversity
of audiences.
The deep-time observation and modeling communities both need to
break into the popular science realm by emphasizing their more compel -
ling and understandable elements. Great opportunities exist for the popu -
larization of ice cap and ocean drilling, both of which occur in dramatic
settings that are unfamiliar and interesting to the general public. These
activities are great examples of science in action, and they show scientists
7 See http://www.uniurb.it/ussp/.
8 See http://www.leopoldleadership.org.
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doing interesting activities in the pursuit of knowledge. Pathways to bring
these activities to the public eye include television shows and series (e.g.,
Discovery Channel, National Geographic Channel, The Daily Show, The
Colbert Report); enhanced presence on the radio (e.g., a paleoclimate feature
on National Public Radio’s (NPR’s) Science Friday, Terry Gross interviews
of proxy data analysts and modelers, Talk radio); Web and Web 2.0 tools
(e.g., www.Ted.com; www.khanacademy.org/, www.story of stuff.com);
Earth system and deep-time blogs using graduate students, scientists, and
science writers (e.g., Andrew Revkin’s New York Times Dot Earth blog9);
popular books and magazine articles; the development of audience-tested
museum exhibits; use of new media (e.g., Podcasts, Twitter, Facebook);
and advertisement and amplification of credible climate websites (e.g.,
NOAA’s climate website10).
Potential Collaborators
Science is now so specialized and complex that most scientists do
not venture far from their particular research area. To obtain broader
understanding of the potential offered by paleoclimate data and modeling
within the larger climate discussion, it is important to create forums where
scientists from different disciplines exchange information and perspec -
tives. This is effectively done within disciplines by talks and symposia at
national meetings (e.g., those hosted by the American Geophysical Union
and the Geological Society of America) and between disciplines at meet-
ings like those hosted by the American Association for the Advancement
of Science. Opportunities to engage broader groups exist at venues such
as industry conferences (e.g., the American Association of Petroleum
Geologists) and environmental conferences (e.g., the Aspen Environment
Forum) with the potential to build a broader collective understanding of
the nature and reliability of proxy data and modeling.
Policy Makers
Ultimately, policy makers require scientifically credible and actionable
data on which to base their policies. Faced with a diversity of opinions,
they need credible sources of information. The IPCC made its findings
very accessible by creating a simple, but multilingual, website that not
only presented the report but also made its images and figures available
for download as PowerPoint files. The creation of simple, but clear, col -
lateral resources such as these should be a goal of deep-time research
9 See http://dotearth.blogs.nytimes.com/.
10 See http://globalchange.gov/; and http://www.realclimate.org.
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projects. A good example is the Cenozoic climate curve of Zachos et al.
(2001a), showing climate change over the last 70 million years using the
proxy of 18O in marine microfossils.
Specific Recommendations
One of the most significant, yet least understood, aspects of the deep-
time climate record is the observation that Earth has moved between two
major climate states—greenhouse and icehouse. Since the last transition
between these two states occurred 34 million years ago at the end of the
Eocene epoch, and the last time the Earth saw a transition from icehouse
to greenhouse was nearly 300 million years ago, this is clearly a story told
only by the deep-time record. This paleoclimate record contains facts that
are startling to most people—there have been times when the poles were
forested rather than being icebound; there were times when the polar seas
were warm; there were times when tropical forests grew at midlatitudes;
more of Earth history has been greenhouse than icehouse. Such relatively
simple but relevant messages provide a straightforward mechanism for
an improved understanding in the broader community of the importance
of paleoclimate studies.
This message can be tailored to different audiences. For children, the
simple comparison that dinosaurs lived in greenhouse conditions and
mammoths lived in ice-house conditions can be an effective way to link a
subject in which they are already interested to a phenomenon that should
also interest them. With the first-order concept that the Earth’s climate
alternates between these two major climate states, it is then possible to
find ways to discuss and explain shorter-wavelength variations in climate,
such as the orbital parameters that drove the glacial and interglacial shifts
of the Pleistocene or the oceanic changes that drive the El Niño cycles.
From the perspective of deep time, it is possible to start with the big
patterns and work toward the small ones, and this is exactly what does
not happen when the story starts from the perspective of daily weather.
The deep-time record also includes examples of extreme climate
events and transitions. These examples are very useful as tools to help
explain the range of possibilities in the Earth’s climate and to show how
certain types of climate events can be abrupt, even when viewed from a
human perspective. Examples such as the subdecadal warmings docu -
mented in the Greenland ice cores are useful to help people understand
that just because something happened a long time ago, does not mean it
took a long time to happen. With this realization, the deep-time record
becomes a storehouse of useful and relevant examples. Ultimately, the goal
of education and outreach from the deep-time perspective should be to
help various audiences understand that the Earth has archived its climate
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history and that this archive—while not fully understood—is perhaps
science’s best tool to understand Earth’s climate future.
Committing to Paleoclimate Education and Outreach
Given the poor state of the public’s understanding of Earth sciences,
and climate science in particular, it is time to commit to the ideal that
education and outreach (E&O) cannot merely be afterthoughts to sci-
entific research activities. By consigning E&O to a relatively minor role
within science institutions and proposals, scientists have inadvertently
but effectively cut off the public from understanding scientific research.
The result has been that a significant percentage of the U.S. public dis -
trusts or ignores scientific climate change information. Accordingly, rather
than promote specific E&O programs, the committee recommends that
there be a renewed commitment within every paleoclimate project to
the dissemination and communication of results to students, teachers,
and the public. The successful E&O activities associated with such pro -
grams as ANDRILL, IODP, and the Incorporated Research Institution for
Seismology (IRIS) show that with an appropriately funded focal point
for scientific interaction—a characteristic of each of these programs—it
is possible to effectively convey rather complex scientific issues and sci -
entific accomplishments to a broader audience. This reinforces the call
for programmatic and funding support for broad-based interdisciplinary
collaborations for deep-time paleoclimate science advanced in this report,
because these collaborative focal points could easily include the type of
dedicated E&O resources as the successful models noted above. Some
existing E&O efforts for deep-time paleoclimatology have been summa -
rized here, but these efforts have to be expanded and more such efforts
should be established. In a field that suffers from chronically low resource
allocations, education and outreach are suffering far more in the area of
paleoclimate than in general climate education. However, students and the
public have always had a particular affinity for Earth history and extreme
events of the past, and accordingly this is a key area for attracting student
and public attention to climate science in general.
