Desert springs and wetlands are among the most biologically productive, diverse, and fragile ecosystems on Earth. They are home to thousands of rare, endemic, and endangered plants and animals and reflect the availability and health of emergent groundwater. Despite the ecological importance of these wetlands, our knowledge of how they might respond to predicted future climate change is limited. This project seeks to understand how springs and wetlands in the Mojave Desert responded to past abrupt warming events, which may be analogs for future conditions. To accomplish this, USGS scientists will reconstruct the hydrologic history of ancient spring ecosystems and establish patterns and rates of change in groundwater availability by investigating paleowetland deposits dating to the latest Pleistocene and Holocene. The results will provide critical information for developing strategies aimed at managing these fragile ecosystems and mitigating the effects of climate change in the arid lands of the American Southwest.
Statement of Problem: The southwestern U.S. is the hottest and driest region in North America and is especially susceptible to drought. Climate models predict this region will become progressively hotter and drier throughout the remainder of the 21st century, and future droughts will be more frequent, intense, and longer lasting than what has been recorded thus far in the historical record. Higher temperatures and changes in the amount and spatial patterns of rainfall and snowpack will affect the lives and economies of more than 50 million people currently living in the region, forcing increased competition for limited water supplies between agriculture and energy sectors, urban populations, and plant and animal life. This presents a tremendous challenge for managing water resources for human consumption while anticipating and minimizing the potential impact on fragile desert ecosystems.
Why this Research is Important: Desert springs and wetlands provide windows into the health of aquifers and groundwater-fed ecosystems in arid environments. They are exceptionally sensitive to changes in climate and can act as harbingers for future conditions, but only if we quantitatively understand how they responded to abrupt climate events in the past. This study will establish the first regional-scale, multi-proxy hydroclimate record for the Mojave Desert that spans the time interval from the latest Pleistocene to Holocene and historical times (approximately the past 15,000 years). The results will provide critical input for federal, state, and local resource managers and other stakeholders for developing strategies aimed at protecting spring ecosystems in light of projected future conditions. In addition, the results will provide robust, ground-truthed data that can be used to test climate models and improve constraints on regional climate projections.
Objective(s): The primary objective of this project is to understand how spring ecosystems responded to subtle and short-lived episodes of abrupt climate change during the recent geologic past. To accomplish this, we will document the response of desert spring ecosystems to climate variability and land-use changes during the late Quaternary. The resulting data will be synthesized to create the first regional-scale hydroclimate record for the southwestern U.S. that spans this time period. These efforts will contribute to the USGS national-scale effort to quantify Holocene hydroclimate conditions and provide critical context to inform current and future management and conservation of extant desert springs and wetlands.
Methods: We will reconstruct past hydroclimate conditions at multiple locations throughout the Mojave Desert by taking a novel approach that combines investigations of paleowetland deposits exposed in geological outcrops and sediment cores taken near active springs. The opportunity to combine these methodologies at sites that are in geographic proximity to one another is rare and will result in more complete and detailed high-resolution hydroclimate records than what could be obtained from either method alone. Sediments exposed in outcrops and in the cores will be described and measured, sampled for geophysical (grain size, density, magnetic susceptibility), geochemical (major and trace elements, stable isotopes), and biological (ostracodes, diatoms, and gastropods) analyses, and dated using a combination of radiocarbon, luminescence, and tephrochronologic techniques. The proxy data will be combined on common temporal scales and compared to existing high-resolution paleowetland records elsewhere in the region, as well as other sources of past climate information such as ice cores, lakes, speleothems, and marine records, to improve our understanding of ecosystem response to abrupt warming events.
Below are other science projects associated with this project.
Past Perspectives of Water in the West
Drivers and Impacts of North Pacific Climate Variability
Pacific Ocean Patterns, Processes, and Productivity (POP3): Impacts of ancient warming on marine ecosystems and western North America
Natural Drought and Flood Histories from Lacustrine Archives
Data release for Seasonality of precipitation in the southwestern United States during the late Pleistocene inferred from stable isotopes in herbivore tooth enamel
Data release for Hydroclimate response of spring ecosystems to a two-stage Younger Dryas event in western North America
Data release for Oxygen isotopes of land snail shells in high latitude regions
Data release for Evidence of humans in North America during the Last Glacial Maximum
Radiocarbon dating of an alluvial deposit with associated faunal remains
Data release for Oxygen isotopes in terrestrial gastropod shells track Quaternary climate change in the American Southwest
Data release for Climatically driven displacement on the Eglington fault, Las Vegas, Nevada, USA
Below are publications associated with this project.
Seasonality of precipitation in the southwestern United States during the late Pleistocene inferred from stable isotopes in herbivore tooth enamel
Hydroclimate response of spring ecosystems to a two-stage Younger Dryas event in western North America
Reply to “Evidence for humans at White Sands National Park during the Last Glacial Maximum could actually be for Clovis people ~13,000 years ago” by C. Vance Haynes, Jr.
Oxygen isotopes of land snail shells in high latitude regions
Response to comment on “Evidence of humans in North America during the Last Glacial Maximum”
Evidence of glacial activity during MIS 4 in the Rocky Mountains, Colorado, USA
Evidence for humans in North America during the Last Glacial Maximum
Aeolian sediments in paleowetland deposits of the Las Vegas Formation
Oxygen isotopes in terrestrial gastropod shells track Quaternary climate change in the American Southwest
Climatically driven displacement on the Eglington fault, Las Vegas, Nevada
Late Quaternary paleohydrology of desert wetlands and pluvial lakes in the Soda Lake basin, central Mojave Desert, California (USA)
The Las Vegas Formation
Below are partners associated with this project.
- Overview
Desert springs and wetlands are among the most biologically productive, diverse, and fragile ecosystems on Earth. They are home to thousands of rare, endemic, and endangered plants and animals and reflect the availability and health of emergent groundwater. Despite the ecological importance of these wetlands, our knowledge of how they might respond to predicted future climate change is limited. This project seeks to understand how springs and wetlands in the Mojave Desert responded to past abrupt warming events, which may be analogs for future conditions. To accomplish this, USGS scientists will reconstruct the hydrologic history of ancient spring ecosystems and establish patterns and rates of change in groundwater availability by investigating paleowetland deposits dating to the latest Pleistocene and Holocene. The results will provide critical information for developing strategies aimed at managing these fragile ecosystems and mitigating the effects of climate change in the arid lands of the American Southwest.
Statement of Problem: The southwestern U.S. is the hottest and driest region in North America and is especially susceptible to drought. Climate models predict this region will become progressively hotter and drier throughout the remainder of the 21st century, and future droughts will be more frequent, intense, and longer lasting than what has been recorded thus far in the historical record. Higher temperatures and changes in the amount and spatial patterns of rainfall and snowpack will affect the lives and economies of more than 50 million people currently living in the region, forcing increased competition for limited water supplies between agriculture and energy sectors, urban populations, and plant and animal life. This presents a tremendous challenge for managing water resources for human consumption while anticipating and minimizing the potential impact on fragile desert ecosystems.
Why this Research is Important: Desert springs and wetlands provide windows into the health of aquifers and groundwater-fed ecosystems in arid environments. They are exceptionally sensitive to changes in climate and can act as harbingers for future conditions, but only if we quantitatively understand how they responded to abrupt climate events in the past. This study will establish the first regional-scale, multi-proxy hydroclimate record for the Mojave Desert that spans the time interval from the latest Pleistocene to Holocene and historical times (approximately the past 15,000 years). The results will provide critical input for federal, state, and local resource managers and other stakeholders for developing strategies aimed at protecting spring ecosystems in light of projected future conditions. In addition, the results will provide robust, ground-truthed data that can be used to test climate models and improve constraints on regional climate projections.
Late Quaternary paleowetland deposits in the Rogers basin of Death Valley National Park, California. Photograph taken by Kathleen Springer in October 2018. Data from this site have not been published. Objective(s): The primary objective of this project is to understand how spring ecosystems responded to subtle and short-lived episodes of abrupt climate change during the recent geologic past. To accomplish this, we will document the response of desert spring ecosystems to climate variability and land-use changes during the late Quaternary. The resulting data will be synthesized to create the first regional-scale hydroclimate record for the southwestern U.S. that spans this time period. These efforts will contribute to the USGS national-scale effort to quantify Holocene hydroclimate conditions and provide critical context to inform current and future management and conservation of extant desert springs and wetlands.
Methods: We will reconstruct past hydroclimate conditions at multiple locations throughout the Mojave Desert by taking a novel approach that combines investigations of paleowetland deposits exposed in geological outcrops and sediment cores taken near active springs. The opportunity to combine these methodologies at sites that are in geographic proximity to one another is rare and will result in more complete and detailed high-resolution hydroclimate records than what could be obtained from either method alone. Sediments exposed in outcrops and in the cores will be described and measured, sampled for geophysical (grain size, density, magnetic susceptibility), geochemical (major and trace elements, stable isotopes), and biological (ostracodes, diatoms, and gastropods) analyses, and dated using a combination of radiocarbon, luminescence, and tephrochronologic techniques. The proxy data will be combined on common temporal scales and compared to existing high-resolution paleowetland records elsewhere in the region, as well as other sources of past climate information such as ice cores, lakes, speleothems, and marine records, to improve our understanding of ecosystem response to abrupt warming events.
USGS scientists collecting sediment cores near Saratoga Springs of Death Valley National Park, California. Photograph taken by Jeff Pigati in February 2017. Data from this site have not been published. - Science
Below are other science projects associated with this project.
Past Perspectives of Water in the West
In the intermountain west, seasonal precipitation extremes, combined with population growth, are creating new challenges for the management of water resources, ecosystems, and geologic hazards. This research contributes a comprehensive long-term context for a deeper understanding of past hydrologic variability, including the magnitude and frequency of drought and flood extremes and ecosystem...Drivers and Impacts of North Pacific Climate Variability
Climate model forecasts indicate an increase in extreme hydrologic events, including floods and droughts, for California and the western U.S. in the future. To better understand what the consequences of this future change in climate may be, USGS scientists are studying the frequency, magnitude, and impacts of past hydroclimate variability and extremes in the region. This project produces well...Pacific Ocean Patterns, Processes, and Productivity (POP3): Impacts of ancient warming on marine ecosystems and western North America
Projections for AD 2100 suggest warming of +1-4°C in the North Pacific Ocean, which will result in widespread transformations throughout the marine environment and western North America. Many of these changes are beyond the predictive capabilities of current climate models. To better address this future uncertainty, our team is developing a geological framework using past warm intervals as...Natural Drought and Flood Histories from Lacustrine Archives
Previous work performed as part of the USGS Holocene Synthesis project illuminated complex centennial-scale patterns of drought and wetter-than-average conditions across the North American continent interior during the past two millennia, where paleorecord data coverage is sparse. In order to explain the patterns of naturally-occurring drought, floods, and storms for the past, identified by the... - Data
Data release for Seasonality of precipitation in the southwestern United States during the late Pleistocene inferred from stable isotopes in herbivore tooth enamel
The late Pleistocene was a climatically dynamic period, with abrupt shifts between cool-wet and warm-dry conditions. Increased effective precipitation supported large pluvial lakes and long-lived spring ecosystems in valleys and basins throughout the western and southwestern U.S., but the source and seasonality of the precipitation are debated. Here we present stable carbon and oxygen isotope dataData release for Hydroclimate response of spring ecosystems to a two-stage Younger Dryas event in western North America
The Younger Dryas (YD) climate event is the preeminent example of abrupt climate change in the recent geologic past. Climate conditions during the YD were spatially complex, and high-resolution sediment cores in the North Atlantic, western Europe, and East Asia have revealed it unfolded in two distinct stages, including an initial stable climatic period between ~12.9 and 12.2 ka associated with aData release for Oxygen isotopes of land snail shells in high latitude regions
The present study investigates the environmental significance of the oxygen isotopic composition of several modern land snail species collected along two north-to-south transects in Alaska and Scandinavia at latitudes between 60 and 70 degrees N. We tested the hypothesis that land snail shell Delta18O values primarily track precipitation Delta18O. The results show that shell Delta18O values from SData release for Evidence of humans in North America during the Last Glacial Maximum
Archaeologists and researchers in allied fields have long sought to understand human colonization of North America. Questions remain about when and how people migrated, where they originated, and how their arrival affected the established fauna and landscape. Here, we present evidence from excavated surfaces in White Sands National Park (New Mexico, United States), where multiple in situ human fooRadiocarbon dating of an alluvial deposit with associated faunal remains
We assessed a construction site in the northern Las Vegas Valley that was initially reported as an "ice age" deposit. Alluvial deposits exposed at the site were inset into the Las Vegas Formation and contained semi-articulated Equus remains. Calibrated radiocarbon dates on two different materials associated with the remains centered on 1957, thus rendering the horse bones as modern.Data release for Oxygen isotopes in terrestrial gastropod shells track Quaternary climate change in the American Southwest
Recent studies have shown the oxygen isotopic composition (delta18O) of modern terrestrial gastropod shells is determined largely by the delta18O of precipitation. This implies that fossil shells could be used to reconstruct the delta18O of paleo-precipitation as long as the hydrologic pathways of the local watershed and the shell isotope systematics are well understood. In this study, we measuredData release for Climatically driven displacement on the Eglington fault, Las Vegas, Nevada, USA
The Eglington fault is one of several intrabasinal faults in the Las Vegas Valley, Nevada, USA, and is the only one recognized as a source for significant earthquakes. Its broad warp displaces Late Pleistocene spring deposits of the Las Vegas Formation, which record hydrologic fluctuations that occurred in response to millennial- and submillennial-scale climate oscillations throughout the late Qua - Publications
Below are publications associated with this project.
Filter Total Items: 23Seasonality of precipitation in the southwestern United States during the late Pleistocene inferred from stable isotopes in herbivore tooth enamel
The late Pleistocene was a climatically dynamic period, with abrupt shifts between cool-wet and warm-dry conditions. Increased effective precipitation supported large pluvial lakes and long-lived spring ecosystems in valleys and basins throughout the western and southwestern U.S., but the source and seasonality of the increased precipitation are debated. Increases in the proportions of C4/(C4+ C3)Hydroclimate response of spring ecosystems to a two-stage Younger Dryas event in western North America
The Younger Dryas (YD) climate event is the preeminent example of abrupt climate change in the recent geologic past. Climate conditions during the YD were spatially complex, and high-resolution sediment cores in the North Atlantic, western Europe, and East Asia have revealed it unfolded in two distinct stages, including an initial stable climatic period between ~ 12.9 and 12.2 ka associated with aReply to “Evidence for humans at White Sands National Park during the Last Glacial Maximum could actually be for Clovis people ~13,000 years ago” by C. Vance Haynes, Jr.
Bennett et al. (2021, Science 373, 1528–1531) reported that ancient human footprints discovered in White Sands National Park, New Mexico date to between ∼23,000 and 21,000 years ago. Haynes (2022, PaleoAmerica, this issue) proposes two alternate hypotheses to explain the antiquity of the footprints. One is that they were made by humans crossing over older sediments sometime during the Holocene. ThOxygen isotopes of land snail shells in high latitude regions
The present study investigates the environmental significance of the oxygen isotopic composition of several modern land snail species collected along two north-to-south transects in Alaska and Scandinavia at latitudes between 60 and 70 °N. We tested the hypothesis that land snail shell δ18O values primarily track precipitation δ18O. The results show that shell δ18O values from Scandinavia were ∼5.Response to comment on “Evidence of humans in North America during the Last Glacial Maximum”
Madsen et al. question the reliability of calibrated radiocarbon ages associated with human footprints discovered recently in White Sands National Park, New Mexico, USA. On the basis of the geologic, hydrologic, stratigraphic, and chronologic evidence, we maintain that the ages are robust and conclude that the footprints date to between ~23,000 and 21,000 years ago.Madsen et al. (1) question the vEvidence of glacial activity during MIS 4 in the Rocky Mountains, Colorado, USA
The Ziegler Reservoir fossil site near Snowmass Village, Colorado, provides a rare opportunity to examine environmental conditions in the Rocky Mountains during marine isotope stage (MIS) 4 (71–57 ka). Although recognized as a global-scale cold event, MIS 4 is typically absent from Rocky Mountain glacial chronologies because the geologic evidence was covered or destroyed during the subsequent, andEvidence for humans in North America during the Last Glacial Maximum
Archaeologists and researchers in allied fields have long sought to understand human colonization of North America. When, how, and from where did people migrate, and what were the consequences of their arrival for the established fauna and landscape are enduring questions. Here, we present evidence from excavated surfaces of in situ human footprints from White Sands National Park (New Mexico, USA)Aeolian sediments in paleowetland deposits of the Las Vegas Formation
The Las Vegas Formation (LVF) is a well-characterized sequence of groundwater discharge (GWD) deposits exposed in and around the Las Vegas Valley in southern Nevada. Nearly monolithologic bedrock surrounds the valley, which provides an excellent opportunity to test the hypothesis that GWD deposits include an aeolian component. Mineralogical data indicate that the LVF sediments are dominated by carOxygen isotopes in terrestrial gastropod shells track Quaternary climate change in the American Southwest
Recent studies have shown the oxygen isotopic composition (δ18O) of modern terrestrial gastropod shells is determined largely by the δ18O of precipitation. This implies that fossil shells could be used to reconstruct the δ18O of paleo-precipitation as long as the isotopic system, including the hydrologic pathways of the local watershed and the gastropod systematics, is well understood. In this stuClimatically driven displacement on the Eglington fault, Las Vegas, Nevada
The Eglington fault is one of several intrabasinal faults in the Las Vegas Valley, Nevada and is the only one recognized as a source for significant earthquakes. Its broad warp displaces late Pleistocene paleo-spring deposits of the Las Vegas Formation, which record hydrologic fluctuations that occurred in response to millennial and submillennial-scale climate oscillations throughout the late QuatLate Quaternary paleohydrology of desert wetlands and pluvial lakes in the Soda Lake basin, central Mojave Desert, California (USA)
Sediment cores taken near extant springs along the western margin of Soda Lake playa, as well as from the playa center, reveal dramatic hydrologic changes that occurred in the central Mojave Desert during the late Quaternary. Results of stratigraphic, chronologic, physical, chemical, and microfossil analyses of seven cores, ranging in length from 5 to 23 m, help refine the timing and character ofThe Las Vegas Formation
The Las Vegas Formation was established in 1965 to designate the distinctive light-colored, fine-grained, fossil-bearing sedimentary deposits exposed in and around the Las Vegas Valley, Nevada. In a coeval designation, the sediments were subdivided into informal units with stratigraphic and chronologic frameworks that have persisted in the literature. Use of the Las Vegas Formation name over the p - Partners
Below are partners associated with this project.