Paleoclimate Research Active
Lessons from the Past, Roadmap for the Future
The present-day climate of the Earth is influenced by a combination of natural climate variability, increased concentrations of greenhouse gases in the atmosphere since the Industrial Revolution, and changes in land cover (such as conversion from forest to agriculture and back again).
To understand the potential range and effect of future climate and how its changes may affect marine and terrestrial systems and society, scientists rely on instrumental records that are at most a few hundred years long and longer geologic records that extend back over thousands and millions of years. The reconstructed records of paleoclimate provide important insights into potential rates and magnitudes of change, warm and cold extremes that lasted for 1000s of years, and large changes in sea level.
Combining paleoclimate data with climate modeling experiments provides a powerful method for discovering and understanding the processes and feedbacks that underlie gradual and abrupt climate change and is an essential component of testing and improving climate models that are used to project possible future climates. Paleoclimate data show how past ecosystems responded to a range of climate and environmental changes and provide an overview of their resilience. The resulting understanding of how natural systems respond to climate forcing can help guide policy makers and managers as they make plans to adapt to climate change.
What is paleoclimatology?
Paleoclimatology is the study of Earth's climate during the entire history of the Earth. Paleoclimate research uses geologic and biologic evidence (climate proxies) preserved in sediments, rocks, tree rings, corals, ice sheets and other climate archives to reconstruct past climate in terrestrial and aquatic environments around the world. Paleoclimate reconstructions provide evidence for the baseline level of climate and environmental variability before humans began using instruments to measure different aspects of climate and weather.
How far back in Earth's history can paleoclimate be reconstructed?
Paleoclimate research spans the history of the Earth. Studies that focus on the last few centuries to millennia produce high-resolution temporal reconstructions of temperature and precipitation that establish a basis for quantifying and understanding natural climate variability. Studies that focus on the past tens-of-thousands to millions of years reveal climate change and variability associated with Earth-Sun geometry and variations in greenhouse gases that controlled the waxing and waning of ice ages, abrupt changes associated with changes in ocean circulation, and geologic processes such as mountain uplift. "Deep-time" paleoclimate studies (prior to ~2.6 million years ago) provide a means to understand extreme climate states and long-term patterns of atmospheric carbon dioxide and climate.
How is past climate reconstructed?
Past climates are reconstructed from a variety of geologic and biologic archives that preserve climate proxies, or evidence of past climate and environment. Examples of archives include terrestrial or aquatic sediments, ice cores from glaciers and ice sheets, tree rings, corals, and packrat middens. These archives contain climate proxies, which are physical, chemical, or biological features that provide information on past climate and environment (such as sea level, air and ocean temperature, atmospheric composition, and precipitation).
How do we know the time period represented by a paleoclimate record?
A variety of analytical techniques are used to determine the ages of the archives and proxies. Typically, dating is used to establish the time of onset, termination, and rate of change of climate events. Many of the dating techniques employed are based on analyzing the nature of radioactive isotopes (e.g., radiocarbon, uranium-thorium) present in sample material. These dating techniques are used in conjunction with other methods such as biostratigraphy (which uses the fossil assemblages contained within a sample to estimate its age) and counting tree rings or annual sediment layers deposited ice and lakes. Other techniques such as surface exposure dating methods are used to estimate the amount of time a sample material such as a boulder deposited by an ice sheet or shoreline has been exposed on the Earth's surface to cosmic rays. Whenever possible, scientists utilize more than one dating method in order to maximize the accuracy and precision of their findings.
How can paleoclimate studies help us better understand potential consequences of future climate change?
Every component of the Earth system affects or is affected by climate. Ecosystems, water availability, carbon cycling, sea level rise, ocean circulation, and ocean acidification all interact with the climate system and respond to changes in climate. Paleoclimate studies provide an essential perspective for assessing the potential impacts of future climate on natural systems and the people who rely on them.
How is paleoclimate research useful for policy and resource managers?
Understanding the response of natural systems to climate forcing can help guide policy makers and managers as they prepare adaptation and mitigation plans for climate change. For example, knowing how past changes in the frequency and amplitude of climate phenomena such as El Niño affected ecosystems provides a framework for exploring policy and management alternatives to mitigate or adapt to future changes. Paleoclimate research that documented the natural range of variability in dissolved oxygen levels was integrated with other evidence to develop dissolved oxygen targets for Chesapeake Bay, and it increasingly is being integrated into management efforts in other critical habitats around the world.
Land-Sea Linkages in the Arctic
Exploring Future Flora, Environments, and Climates Through Simulations (EFFECTS)
Geologic Records of High Sea Levels
Holocene Hydroclimate of Western North America
Paleohydrology of Desert Wetlands
Terrestrial Records of Holocene Climate Change: Fire, climate and humans
Terrestrial Rates and Amplitudes of Changes in Ecoclimate Systems (TRACES)
Mg/Ca ratios in ostracode genera Sarsicytheridea and Paracyprideis: A potential paleotemperature proxy for Arctic and subarctic continental shelf and slope waters
Arctic Ocean stratification set by sea level and freshwater inputs since the last ice age
A multi-decadal geochemical record from Rano Aroi (Easter Island/Rapa Nui): Implications for the environment, climate and humans during the last two millennia
Geomorphic history of Lake Manix, Mojave Desert, California: Evolution of a complex terminal lake basin
Middle and late Pleistocene pluvial history of Newark Valley, central Nevada, USA
Holocene evolution of sea-surface temperature and salinity in the Gulf of Mexico
From saline to freshwater: The diversity of western lakes in space and time
Holocene hydroclimatic reorganizations in northwest Canada inferred from lacustrine carbonate oxygen isotopes
Past abrupt changes, tipping points and cascading impacts in the Earth system
Miocene neritic benthic foraminiferal community dynamics, Calvert Cliffs, Maryland, USA: Species pool, patterns and processes
The Miocene stratigraphy of the Laberinto area (Río Ica Valley) and its bearing on the geological history of the East Pisco Basin (south-central Peru)
Long-term African dust delivery to the eastern Atlantic Ocean from the Sahara and Sahel regions: Evidence from Quaternary paleosols on the Canary Islands, Spain
- Overview
Lessons from the Past, Roadmap for the Future
The present-day climate of the Earth is influenced by a combination of natural climate variability, increased concentrations of greenhouse gases in the atmosphere since the Industrial Revolution, and changes in land cover (such as conversion from forest to agriculture and back again).
To understand the potential range and effect of future climate and how its changes may affect marine and terrestrial systems and society, scientists rely on instrumental records that are at most a few hundred years long and longer geologic records that extend back over thousands and millions of years. The reconstructed records of paleoclimate provide important insights into potential rates and magnitudes of change, warm and cold extremes that lasted for 1000s of years, and large changes in sea level.
Combining paleoclimate data with climate modeling experiments provides a powerful method for discovering and understanding the processes and feedbacks that underlie gradual and abrupt climate change and is an essential component of testing and improving climate models that are used to project possible future climates. Paleoclimate data show how past ecosystems responded to a range of climate and environmental changes and provide an overview of their resilience. The resulting understanding of how natural systems respond to climate forcing can help guide policy makers and managers as they make plans to adapt to climate change.
What is paleoclimatology?
Paleoclimatology is the study of Earth's climate during the entire history of the Earth. Paleoclimate research uses geologic and biologic evidence (climate proxies) preserved in sediments, rocks, tree rings, corals, ice sheets and other climate archives to reconstruct past climate in terrestrial and aquatic environments around the world. Paleoclimate reconstructions provide evidence for the baseline level of climate and environmental variability before humans began using instruments to measure different aspects of climate and weather.
How far back in Earth's history can paleoclimate be reconstructed?
Paleoclimate research spans the history of the Earth. Studies that focus on the last few centuries to millennia produce high-resolution temporal reconstructions of temperature and precipitation that establish a basis for quantifying and understanding natural climate variability. Studies that focus on the past tens-of-thousands to millions of years reveal climate change and variability associated with Earth-Sun geometry and variations in greenhouse gases that controlled the waxing and waning of ice ages, abrupt changes associated with changes in ocean circulation, and geologic processes such as mountain uplift. "Deep-time" paleoclimate studies (prior to ~2.6 million years ago) provide a means to understand extreme climate states and long-term patterns of atmospheric carbon dioxide and climate.
How is past climate reconstructed?
Past climates are reconstructed from a variety of geologic and biologic archives that preserve climate proxies, or evidence of past climate and environment. Examples of archives include terrestrial or aquatic sediments, ice cores from glaciers and ice sheets, tree rings, corals, and packrat middens. These archives contain climate proxies, which are physical, chemical, or biological features that provide information on past climate and environment (such as sea level, air and ocean temperature, atmospheric composition, and precipitation).
How do we know the time period represented by a paleoclimate record?
A variety of analytical techniques are used to determine the ages of the archives and proxies. Typically, dating is used to establish the time of onset, termination, and rate of change of climate events. Many of the dating techniques employed are based on analyzing the nature of radioactive isotopes (e.g., radiocarbon, uranium-thorium) present in sample material. These dating techniques are used in conjunction with other methods such as biostratigraphy (which uses the fossil assemblages contained within a sample to estimate its age) and counting tree rings or annual sediment layers deposited ice and lakes. Other techniques such as surface exposure dating methods are used to estimate the amount of time a sample material such as a boulder deposited by an ice sheet or shoreline has been exposed on the Earth's surface to cosmic rays. Whenever possible, scientists utilize more than one dating method in order to maximize the accuracy and precision of their findings.
How can paleoclimate studies help us better understand potential consequences of future climate change?
Every component of the Earth system affects or is affected by climate. Ecosystems, water availability, carbon cycling, sea level rise, ocean circulation, and ocean acidification all interact with the climate system and respond to changes in climate. Paleoclimate studies provide an essential perspective for assessing the potential impacts of future climate on natural systems and the people who rely on them.
How is paleoclimate research useful for policy and resource managers?
Understanding the response of natural systems to climate forcing can help guide policy makers and managers as they prepare adaptation and mitigation plans for climate change. For example, knowing how past changes in the frequency and amplitude of climate phenomena such as El Niño affected ecosystems provides a framework for exploring policy and management alternatives to mitigate or adapt to future changes. Paleoclimate research that documented the natural range of variability in dissolved oxygen levels was integrated with other evidence to develop dissolved oxygen targets for Chesapeake Bay, and it increasingly is being integrated into management efforts in other critical habitats around the world.
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Land-Sea Linkages in the Arctic
The Arctic is undergoing historically unprecedented changes in weather, sea ice, temperature and ecosystems. These changes have led to greater coastal erosion, greater export of freshwater, and changes to marine and terrestrial ecosystems, habitats, and productivity, among other trends. Meanwhile, many believe the Arctic “amplifies” large climate changes during both warm periods and ice ages and...Exploring Future Flora, Environments, and Climates Through Simulations (EFFECTS)
Climate changes can significantly affect species and ecosystems. Historical and paleoenvironmental data record species and ecosystem responses to past climate changes, but these records become sparse as one goes further back in time. Model simulations can be used fill the spatial and temporal gaps in observed records to improve our understanding of the potential magnitude, rate, and spatial...Geologic Records of High Sea Levels
This project studies past high sea levels on coastlines that preserve fossil coral reefs or marine terraces. We ascertain the magnitudes of sea-level high stands by field mapping, stratigraphic measurements, and precise elevation measurements. Geochronology is accomplished by radiocarbon dating of mollusks (for Holocene-to-last-glacial deposits), uranium-series dating of corals (for high-sea...Holocene Hydroclimate of Western North America
The objectives of this project are to reconstruct detailed histories of Holocene hydroclimate and corresponding environmental change from geological archives such as lake sediment, peat, and wood to more fully understand past, ongoing, and future change and its impacts.Paleohydrology of Desert Wetlands
Springs and wetlands are among the most highly threatened ecosystems on Earth. Although geographically limited, they support more than 20% of all the threatened and endangered species in the United States. Scientists from the U.S. Geological Survey are examining the rock record to determine how springs and wetlands responded to abrupt climate change during prehistoric times and the recent geologic...Terrestrial Records of Holocene Climate Change: Fire, climate and humans
Large wildfires have raged across the western Americas in the past decade including the Las Conchas, New Mexico fire that burned 44,000 acres in a single day in 2011 (Orem and Pelletier, 2015, Geomorphology 232: 224-238, and references therein), the 2016 Fort McMurray, Alberta fire that required evacuating an entire city, and the 2015 Alaskan fire season that burned more than 5 million acres...Terrestrial Rates and Amplitudes of Changes in Ecoclimate Systems (TRACES)
Vegetation changes caused by climatic variations and/or land use may have large impacts on forests, agriculture, rangelands, natural ecosystems, and endangered species. Climate modeling studies indicate that vegetation cover, in turn, has a strong influence on regional climates, and this must be better understood before models can estimate future environmental conditions. To address these issues... - Data
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Mg/Ca ratios in ostracode genera Sarsicytheridea and Paracyprideis: A potential paleotemperature proxy for Arctic and subarctic continental shelf and slope waters
We evaluate the potential utility of Mg/Ca ratios in the sublittoral ostracode genera Sarsicytheridea and Paracyprideis as a paleotemperature proxy for continental shelf and upper slope waters of the Arctic Ocean and adjacent seas. Using sediment core-top and surface sediment samples, the shells of three species, S. bradii, S. punctillata, and P. pseudopunctillata, were analyzed from Arctic OceanAuthorsThomas M. Cronin, Gary S. Dwyer, Katherine Keller, Laura Gemery, Jesse R. FarmerArctic Ocean stratification set by sea level and freshwater inputs since the last ice age
Salinity-driven density stratification of the upper Arctic Ocean isolates sea-ice cover and cold, nutrient-poor surface waters from underlying warmer, nutrient-rich waters. Recently, stratification has strengthened in the western Arctic but has weakened in the eastern Arctic; it is unknown if these trends will continue. Here we present foraminifera-bound nitrogen isotopes from Arctic Ocean sedimenAuthorsJesse R. Farmer, Daniel Sigman, Julie Granger, Ona M. Underwood, Francois Frapiat, Thomas M. Cronin, Alfredo Martínez-García, Gerald H. HaugA multi-decadal geochemical record from Rano Aroi (Easter Island/Rapa Nui): Implications for the environment, climate and humans during the last two millennia
The small and remote Easter Island (Rapa Nui) has a complex and still partially unknown history of human colonization and interactions with the environment. Previous research from sedimentary archives collected in the three freshwater bodies of Rapa Nui document dramatic environmental changes over the last two millennia. Yet, the characteristics of sediments and paleoenvironmental records are chalAuthorsMarco Roman, David B. McWethy, Natalie Kehrwald, Evans Osayuki Erhenhi, Amy E. Myrbo, José M. Ramirez Aliaga, Anibal Pauchard, Clara Turetta, Carlo Barbante, Matthew Prebble, Elena Argiriadis, Dario BattistelGeomorphic history of Lake Manix, Mojave Desert, California: Evolution of a complex terminal lake basin
The US Environmental Protection Agency's short-term freshwater effluent test methods include a fish (Pimephales promelas), a cladoceran (Ceriodaphnia dubia), and a green alga (Raphidocelis subcapitata). There is a recognized need for additional taxa to accompany the three standard species for effluent testing. An appropriate additional taxon is unionid mussels because mussels are widely distributeAuthorsMarith C. Reheis, David M. Miller, James B. Paces, Charles G. Oviatt, Joanna R. Redwine, Darrell Kaufman, Jordon Bright, Elmira WanMiddle and late Pleistocene pluvial history of Newark Valley, central Nevada, USA
Newark Valley lies between the two largest pluvial lake systems in the Great Basin, Lake Lahontan and Lake Bonneville. Soils and geomorphology, stratigraphic interpretations, radiocarbon ages, and amino acid racemization geochronology analyses were employed to interpret the relative and numerical ages of lacustrine deposits in the valley. The marine oxygen isotope stage (MIS) 2 beach barriers areAuthorsJoanna L. Redwine, R. M. Burke, Marith C. Reheis, R. J. Bowers, Jordon Bright, D. S. Kaufman, R. M. ForesterHolocene evolution of sea-surface temperature and salinity in the Gulf of Mexico
Flows into and out of the Gulf of Mexico (GoM) are integral to North Atlantic ocean circulation, and help facilitate poleward heat transport in the Western Hemisphere. The GoM also serves as a key source of moisture for much of North America. Modern patterns of sea-surface temperature (SST) and salinity in the GoM are influenced by the Loop Current, its eddy-shedding dynamics, and the ensuing inteAuthorsKaustubh Thiumalai, Julie N. Richey, Terrence M. QuinnFrom saline to freshwater: The diversity of western lakes in space and time
Beginning with the nineteenth-century territorial surveys, the lakes and lacustrine deposits in what is now the western United States were recognized for their economic value to the expanding nation. In the latter half of the twentieth century, these systems have been acknowledged as outstanding examples of depositional systems serving as models for energy exploration and environmental analysis, mHolocene hydroclimatic reorganizations in northwest Canada inferred from lacustrine carbonate oxygen isotopes
Sub-centennial oxygen (δ18O) isotopes of ostracod and authigenic calcite from Squanga Lake provides evidence of hydroclimatic extremes and a series of post-glacial climate system reorganizations for the interior region of northwest Canada. Authigenic calcite δ18O values range from −16‰ to −21‰ and are presently similar to modern lake water and annual precipitation values. Ostracod δ18O record nearAuthorsG. Everett Lasher, Mark B. Abbott, Lesleigh Anderson, Lindsey Yasarer, Michael Rosenheimer, Bruce P. FinneyPast abrupt changes, tipping points and cascading impacts in the Earth system
The geological record shows that abrupt changes in the Earth system can occur on timescales short enough to challenge the capacity of human societies to adapt to environmental pressures. In many cases, abrupt changes arise from slow changes in one component of the Earth system that eventually pass a critical threshold, or tipping point, after which impacts cascade through coupled climate–ecologicaAuthorsV. Brovkin, Edward J. Brook, J. Williams, S. Bathiany, T. Lenton, M. Barton, R. DeConto, J. Donges, A. Ganopolski, J. McManus, Summer K. Praetorius, A. de Vernal, A. Abe-Ouchi, H. Cheng, M Claussen, M. Crucifix, Virginia Iglesias, Darrell S. Kaufman, T. Kleinen, Fabrice Lambert, Sander van der Leeuw, Hannah Liddy, Marie-France Loutre, David McGee, Kira Rehfeld, Rachael H. Rhodes, Alistair W.R. Seddon, Lilian Vanderveken, Zicheng YuMiocene neritic benthic foraminiferal community dynamics, Calvert Cliffs, Maryland, USA: Species pool, patterns and processes
The presence/absence and abundance of benthic foraminifera in successive discrete beds (Shattuck “zones”) of the Miocene Calvert and Choptank formations, exposed at the Calvert Cliffs, Maryland, USA, allows for investigation of community dynamics over space and time. The stratigraphic distribution of benthic foraminifera is documented and interpreted in the context of sea-level change, sequence stAuthorsStephen J. Culver, Seth R Sutton, David J. Mallinson, Martin A Buzas, Marci M. Robinson, Harry J. DowsettThe Miocene stratigraphy of the Laberinto area (Río Ica Valley) and its bearing on the geological history of the East Pisco Basin (south-central Peru)
Global sea-level changes and substantial vertical displacement along the Monte Grande Fault (MGF) in the lower Río Ica Valley of south-central Peru influenced the accumulation of bioclast-bearing and diatom-bearing Miocene siliciclastic sediments in an area of the East Pisco forearc basin (EPB) colloquially known as Laberinto. Two depositional hiatuses in the Laberinto area (∼17–14 Ma, ∼12.5–10 MaAuthorsThomas J. Devries, John A. Barron, Mario Urbina-Schmitt, Diana Ochoa, Raúl Esperante, Lawrence W SneeLong-term African dust delivery to the eastern Atlantic Ocean from the Sahara and Sahel regions: Evidence from Quaternary paleosols on the Canary Islands, Spain
Africa is the most important source of dust in the world today and dust storms from that continent frequently deposit sediment on the nearby Canary Islands. Many investigators have inferred African dust inputs to Canary Islands paleosols based only on the presence of quartz. However, some local rocks do contain this mineral, so quartz alone is insufficient proof of dust deposition. Further, it isAuthorsDaniel R. Muhs, Joaquín Meco, James R. Budahn, Gary L. Skipp, Kathleen R. Simmons, Mathew C. Baddock, J.T. Betancort, A. Lomoschitz