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Sciences and Exploration Directorate

Allegra Nicole LeGrande

(RSCH AST, ATMOSPHERIC CHEMISTRY & DYN)

Allegra Nicole LeGrande's Contact Card & Information.
Email: allegra.n.legrande@nasa.gov
Phone: 212.678.5556
Org Code: 611
Address:
NASA/GISS
 Mail Code 611
 New York, NY 10025
Employer:
NASA

Brief Bio

Future climate change will likely be beyond the range of the observational 'training period' over which all of our state-of-the-art climate models were designed. I specialize in finding ways to characterize climates more extreme than the historical period, implementing a means to validate the climate model against these extremes, and finally improving the model in instances where there is a mismatch between simulated and inferred (from proxy archives) climates.

I am interested in the hydrologic cycle, and in particular tracers of the hydrologic cycle such as water isotopologues. These tracers are useful for establishing the provenance and (rainout) history of air parcels. They are also useful as a tracer of past climates (ice cores, cave deposits, ocean sediment cores, etc.). I do experiments with a general circulation model (the kind used in predicting future climate change) to discover details about the hydrologic cycle in the past and present in hopes of improving our ability to understand this part of the climate in the future.

Research Interests

Water Isotopologues as Proxy Indicators of the Hydrologic Cycle

Earth Science: Climate

Water isotope distribution in the atmosphere is impacted by initial composition (ocean composition) and transport and rainout history. In the ocean, composition regionally follows the freshwater balance. The tracer is measured in modern ocean and air samples as well as in satellite retrievals. Its past composition is preserved in many fossils containing old water (e.g., ice cores) or oxygen/hydrogen (e.g., calcium carbonate which makes up the shells of zooplankton, speleotems; tree cellulose; etc.)


Modern: Water isotopologues in the ocean are too disperse to explicitly produce a gridded data set. Here is my project to determine 3D water isotopologue fields for the ocean: http://data.giss.nasa.gov/o18data/

Parameterizations of processes within the simulated clouds and convection schemes alters the composition of water isotopes, which are often more sensitive than traditional climate diagnostics. These tracers can then be constrained against both modern and past observations to determine the best suite of parameterizations to represent clouds and convection processes.


Past:I use the NASA Goddard Institute for Space Studies general circulation model, ModelE2 that has been enabled with tracers of the hydrologic cycle, water isotopolgoues (H217O, HDO and H2O18). We also include vapor source distribution tracers which are complementary to the water isotopologues and allow the explicit diagnosis of water provenance within the model.

The inclusion of the tracers allows me to simulate past climates and constrain the performance of the model (via these tracers) against measured archives of past climate. These archives include ice cores, speleothems (cave deposits), foraminifera and ostracodes (ocean/lake sediment cores), tree cellulose, and corals. Testing the model in times in which it wasn't designed to perform allows us to measure its skill. This should improve our confidence in its future simulations -- also a time where climate will be beyond the modern range of climate observations.

 

Impact of Large Strato-Volcanic Eruptions on Climate

Earth Science: Aerosols

In long climate experiments, volcanic aerosols (principally sulfate) are currently treated in a very parameterized way such that every volcano in a general circulation model resembles the 1991 eruption of Mt. Pinatubo. I use the more sophisticated aerosol and chemistry, 'MATRIX' model components of the NASA Goddard Institute for Space Studies general circulation model, ModelE2.1 to explicitly simulate large strato-volcanic events. I explore the impact of various types of emissions on atmospheric chemistry and climate.

http://www.pages-igbp.org/ini/wg/ocean2k/161-initiatives/working-group/vics/1290-vics

Coordinated experiments: http://volmip.org

Observing Atmospheric Rivers with the NASA-CYGNSS GPS array

Earth Science: Precipitation

Atmospheric rivers (ARs) are a principal mechanism for poleward transport of water vapor; they sometimes generate catastrophic inland flooding for the US west coast in the Midwest US, Europe, and Asia; at the same time, ARs are an important water source. Despite their importance, the study of the mechanisms for AR development and variability is an emerging field, and the expected changes in atmospheric rivers with anthropogenic climate change lack a unified theory. One issue is the uncertainty about the roles of near-surface and upper-level dynamics in helping or suppressing AR development. Moisture sources within developing and sustaining ARs add another source for uncertainty – moisture can be sourced non-locally through advection or/and locally from surface fluxes, but the relative proportions of each, and their links to spatial patterns of variability, are poorly constrained. Part of the reason ARs are not fully understood is that they often initiate over the ocean, often under heavy cloud cover in regions with relatively sparse data.


The Cyclone Global Navigation Satellite System (CYGNSS) provides a dataset that can be leveraged to improve our understanding of ARs through improved surface wind speed data in the tropics and subtropics, extending up through 38 ̊ latitude, a principal genesis region of AR development. CYGNSS data provides critical information in regions where there are few other near-surface observations in (often heavily) precipitating conditions -- CYGNSS’ longitudinal coverage is near complete at the daily time scale. Given that surface winds generated by models, including reanalyses, require a complex balance between surface, boundary layer, and, sometimes, convection parameterizations, the new wealth of information provided by CYGNSS is crucial for our attempts at understanding phenomena such as ARs. 

Tracers of Provenance: Global Water and Energy Balance

Earth Science: Precipitation

I use general circulation (NASA Goddard Institute for Space Studies, ModelE2) model experiments paired with satellite measurements (Tropospheric Emission Spectrometer on AURA) of water isotopologues in water vapor (strongly related to the concentration in precipitation) to determine the provenance (origination) of moisture in thd lower to mid troposphere. This process improves our understanding of the tropical hydrologic cycle.

In addition, I use synthetic model tracers, 'vapor source distribution' tracers, that can explicitly determine moisture provenance within the model simulation. These tracers aid in interpreting observations of water isotopologues. In addition, they can be used to construct detailed water and energy budgets within the model.

Ice Sheet Health

Earth Science: Mass Balance

Future sea level rise is highly dependent on contributions from the melting of glacial ice in Greenland and Antarctica. Our understanding of future contributions from these sources is limited, however, because the timescale through which ice sheet mass comes into balance with climate forcing could be decades to centuries, depending on the magnitude and rapidity of the forcing. I use both past climate simulations of ice sheet mass balance as well as modern simulations to assess the climate models ability to capture changes in ice sheet health, with a focus on surface mass balance.

Characterizing feedbacks to natural climate forcings on long time scales

Simulations of the last 1000 years conducted for the PMIP (paleoclimate model intercomparison project) are computationally expensive, often taking over one year of real time to complete. Because of this expense, simpler, more parameterized versions of the climate model are used (i.e., the NINT, non-interactive aerosols / atmospheric chemistry version) since these more sophisticated versions would multiply the computational time by a factor of 3 to 5.

However, these parameterizations do not include some important feedbacks, leading to deficits in the simulation of the largest volcanic eruptions and excluding atmospheric chemistry feedbacks to volcanoes and changes in incoming solar radiation (~1.5 W/m2 in TSI). Both of these natural climate forcings alter chemistry of the stratosphere, such as ozone, which impacts surface climate.

Using GISS ModelE2.1 and ModelE2.2, I conduct experiments that sample the extremes of natural climate forcing for the last 2000 years. Then, I implement improved parameterizations of these events using various regression techniques. The resulting model simulation better captures the extent of climate variability through including atmospheric chemistry feedbacks without causing the model simulation to triple or more in time.

Constraining Equilibrium Climate Sensitivity with a Paleoclimate Perturbed Parameter Ensemble constrained against Assimilated Paleoclimate Data

Clouds and Convection Parameterizations are necessary in climate models because the processes they represent are too small to explicitly resolve. Choices for these parameters are typically made based on validation against observations from the historical period -- often concentrated on the satellite era of the last 40 years. However, future climate change is well beyond the variability expressed during this period.


Climates of the past were much more variable than the historic period. The magnitude of the forcing driving these past climate changes is of similar magnitude to that we expect to occur in the future. The prospect of these 'out of sample tests' to validate climate models has been around in theory for decades. Here we provide a quantitative framework for constraining an ensemble of simulations from GISS-E3 (CMIP7) and GISS-E2.1 (CMIP6) to determine which parameter sets are most robust across a broad spectrum of climates. These parameter sets then are applied to doubled CO2 experiments to assess the equilibrium climate sensitivity of each, with the sensitivity of parameter suites with excellent past climate agreement ranked more highly.


This methodology refines the magnitude of our temperature projections during future climate change.

Current Projects

Using tracers to understand the Tropical Hydrologic Cycle

Which moisture source fuels convection during the MJO (Madden Julian Oscillation)? What impact does the MJO have on large rain events like atmospheric rivers?

I use the TES (tropospheric emission spectrometer on AURA) instrument's measurements of specific humidity and deuterated (HDO) water paired with the NASA Goddard Institute for Space Studies general circulation model, ModelE2.1 simulations to understand the tropical hydrologic cycle -- especially modes of variability including the Madden-Julian Oscillation and El Nino Southern Oscillation. I pair these with water provenance tracers built into GISS ModelE2.1 to understand the tropical water cycle.
 

Paleoclimate Model Intercomparison Project, Phase 4

This project has target simulations for general circulation models of past climate where proxy archives have been compiled. These experiments include 21 000 years ago (last glacial maximum), deglaciation, 6 000 years ago (mid-Holocene). Other projects include the last millennium (850 AD to present) and Eocene (55 million years ago).

I have completed simulations with NASA Goddard Institute for Space Studies general circulation model, ModelE2.1-R for this project.
 

Role of eruptive volcanic emissions on atmospheric composition and climate

Aerosols

The representation of volcanic eruptions in climate models introduces some of the largest errors when evaluating historical simulations, partly due to the crude model parameterizations. Several crucial areas of representing volcanic eruptions are investigated here: 1) the processes of converting sulfur dioxide to sulfate aerosol, the resulting aerosol size distribution and its evolution with time, by simulating and evaluating against measurements of the most recent large volcanic eruption (Mt. Pinatubo in 1991); 2) the impacts of eruptions with different characteristics on climate; 3) the role of water vapor and halogen injection on atmospheric composition and climate, and role of the multiple small eruptions that occurred during the last 15 years in the Earth system. We will evaluate the role volcanic eruptions play in atmospheric composition and climate using two different global models which are both able to simulate aerosol microphysics: the NASA GISS-E2, which represents aerosol size in logarithmic modes, and WACCM/CARMA, which represents aerosol size in discrete bins. This will allow us to prognostically determine the impact of gaseous emissions on climate and atmospheric composition, coming from both large eruptions that penetrate the stratosphere, and smaller ones that inject material only in the troposphere. A wealth of remotely sensed data will be used to evaluate the models, help improve the model assumptions, and, ultimately, model skill.

Sensitivity of Climate Variability to Anthropogenic and Natural Drivers during the Last Millennium

To understand the degree and causes of climate variability during the last millennium.
The interactions between forcings and intrinsic variability are complicated, and the proxy records of climate response are by definition indirect measures. An ensemble of millennial-length simulations with the Goddard Institute for Space Studies GCM (ModelE2-R) is proposed to identify regional and temporal climate “fingerprints” from potentially important forcing mechanisms. In addition, the model's Earth System components (chemistry, aerosols, water isotopes, and wetland methane emissions) will be included in time-slices of particular interest – such as the early medieval (MT, 1000-1200) or Maunder Minimum (MM, 1550-1750).

Determining the Health and Details of the Last Disappearance of a Land Ice Sheet.

Modern: With water isotopologue and water provenance tracers enabled, I conduct modern simulations of surface mass and energy balance of land ice sheets (Greenland and Antarctica). These make use of a sub-grid-scale scheme (elevation classes) to better characterize the narrow ablation zone. Sources of water and energy transport to land ice and the variability of this transport is diagnosed using additional model tracers.

Past: Using the NASA Goddard Institute for Space Studies general circulation model, ModelE2.1-R, I simulated roughly millennial time slice experiments from 24 000 years ago to 6 000 years ago, covering the period during which the Laurentide Ice Sheet was at its maximum to its disappearance. At each step, appropriate boundary conditions are assigned (topography, greenhouse gas concentration, vegetation changes, orbital changes), and the surface energy mass balance above the Laurentide is assessed. These results are then used to drive an offline energy mass balance ice sheet model. This process allows us to determine in detail the harbingers of ice sheet demise. The goal of this project is to assess the future health of the Land Ice Sheet.

Future: I apply similar techniques and analysis from the modern and past ice sheets to estimate ice sheet health in the future.

Yale Nile Initiative - Humans History and Explosive Volcanism

This project examines the link between explosive volcanic eruptions and the annual Nile river summer flooding in antiquity -- and evaluates if humans were able to impact climate through land us modifications. Large volcanic eruptions can reduce average global temperatures and suppress average global precipitation. This is known to have had dramatic effects on annual rainfall on the Nile watershed over the last several millennia. The human response to this annual flooding, and to its variability over the years, was the major driver of Egyptian history up to the completion of the high dam at Aswan in 1970. 
A collaboration among historians, climate scientists, hydrologists, and statisticians, this project seeks to understand the coupling between the hydrological cycle and human society in Egypt during the Hellenistic era (305 BCE - 30 BCE), a well-documented period of economic, technological and social change with often violent rivalries between major regional powers. The results will also inform our understanding of best-practice responses to the changing climate in the modern world. The project will inform the broad public about human and natural systems and the complex interactions between them at diverse scales, through a traveling exhibition program developed at the Yale Peabody Museum of Natural History. https://nileclimateproject.netlify.com

Atmospheric Rivers in a Changing Climate

Atmospheric Rivers are narrow bands of moisture transported through the atmosphere, and an important source of poleward atmospheric heat transport. Where these encounter land, orographic lift occurs, yielding extreme precipitation events.


What processes are linked with atmospheric rivers? How will these be modulated in the future? How is the representation of atmospheric rivers in climate models influenced by simulated surface wind speed, latent and sensible heat fluxes, and clouds and convective parameterizations? I am exploring this topic using the GISS climate model, which is equipped with special tracers of the water cycle, include water isotopologue tracers and water provenance (vapor source distribution) tracers.


I am working with research partners at Columbia and City College of New York to understand Atmospheric Rivers by comparing GISS climate model simulations to the surface observations of the NASA Cyclone Global Navigation Satellite System data product (https://www.nasa.gov/cygnss).

4-OCEANS: Human History of Marine Life; Extraction, Knowledge, Drivers, and Consumption of Marine Resources 100BCE to 1860

4-OCEANS aims to assess the importance of marine life for human societies during the last two millennia. We contend that the harvest of marine resources played a critical, but as yet underappreciated and poorly understood, role in global history. To bridge this gap in our understanding, the four PIs will form an interdisciplinary team combining expertise in marine environmental history, climate history, natural history, geography, historical ecology and zooarchaeology. We will examine when and where marine exploitation was of significance to human society; how selected major socio-economic, cultural, and environmental forces variously constrained and enabled marine exploitation; and identify the consequences of marine resource exploitation for societal development. Through these objectives we will discover how marine resources as novel wealth altered societies throughout history. How might marine wealth have enabled some societies to escape food shortages? How did it trigger long-term socio-economic impacts and ecological consequences? How were marine resources valued, consumed, and energetically transformed? Revealing this history will open a new window on human-nature dynamics of profound importance for understanding developmental trajectories of human societies. 4-OCEANS will transcend the binary distinctions of East and West, global-north and global-south, indigenous and colonial, resource exploitation and wildlife conservation, nature and culture. In doing so, 4-OCEANS will uncover and chart historical trajectories towards sustainable and unsustainable food security and resource extraction, identifying their complex underlying drivers. 

Positions/Employment

Physical Research Scientist

NASA Goddard Institute for Space Studies - New York, NY

September 2009 - Present


Adjunct Assistant Research Scientist

Columbia University (adjunct, unpaid) - New York, NY

September 2009 - Present


Associate Research Scientist

Columbia University - New York, NY

March 2009 - September 2009


Postdoctoral Research Scientist

Columbia University - New York, NY

September 2007 - March 2009


Education

PhD: Columbia University 2007 -- Earth Sciences (adv: Gavin Schmidt & Wallce Broecker)
MSc: Columbia University 2005 -- Earth Sciences (adv: Gavin Schmidt & Wallce Broecker)
MA:   Columbia University 2003 -- Earth Sciences (adv: Jean Lynch Stieglitz & Gavin Schmidt)
BSc : Rice University 2001 -- Geophysics, Geology, Anthropology
          University of Leeds 1999 -- Study Abroad Geophysics
Robert E. Lee High School, Midland, Texas

Publications

Refereed

2025. "Leaf wax hydrogen isotopes reflect storm track position over western North America.", Paleoceanography and Paleoclimatology, [10.22541/essoar.176002485.58604019/v1] [Journal Article/Letter]

2025. "H11 meltwater and standard 127 ka Last Interglacial simulations suggest more modest peak temperatures for both Greenland and Antarctica: a multi-model study of water isotopes.", Climate of the Past, 21 (10): 1725-1753 [10.5194/cp-21-1725-2025] [Journal Article/Letter]

2025. "Water Isotope Model Intercomparison Project (WisoMIP): Present-day Climate.", Journal of Geophysical Research: Atmospheres, [10.22541/essoar.175330911.17791287/v1] [Journal Article/Letter]

2025. "Green Sahara influence on South Atlantic dynamics: insights from NASA GISS simulations.", Journal of Southern Hemisphere Earth Systems Science, 75 (2): [10.1071/es24031] [Journal Article/Letter]

2025. "North Pacific ocean–atmosphere responses to Holocene and future warming drive Southwest US drought.", Nature Geoscience, 18 (7): 646-652 [10.1038/s41561-025-01726-z] [Journal Article/Letter]

2025. "Ocean Meridional Overturning Circulation During the Early and Middle Miocene.", Paleoceanography and Paleoclimatology, 40 (4): [10.1029/2024pa005055] [Journal Article/Letter]

2025. "Exploring Precipitation Triple Oxygen Isotope Dynamics: Insights From GISS-E2.1 Simulations.", Journal of Advances in Modeling Earth Systems, 17 [10.1029/2024MS004509] [Journal Article/Letter]

2024. "Modelling framework for asynchronous land-atmosphere coupling using NASA GISS ModelE and LPJ-LMfire: Design, Application and Evaluation for the 2.5ka period.", Geoscience Model Development Discussions, [10.5194/gmd-2024-219] [Journal Article/Letter]

2024. "Assessing the Impact of Climate Change on Atmospheric Rivers: A Modeling Perspective.", Journal of Geophysical Research: Atmospheres, 129 (12): [10.1029/2023jd040074] [Journal Article/Letter]

2024. "Just How River‐Like Are Atmospheric Rivers?.", Geophysical Research Letters, 51 (10): [10.1029/2023gl105828] [Journal Article/Letter]

2024. "Precipitation 17-O‐Excess Altered During Tropical Convection: Evidence From Monsoon Cold Surges in Singapore.", Journal of Geophysical Research: Atmospheres, 129 (9): [10.1029/2023jd040437] [Journal Article/Letter]

2023. "The impact of ENSO and NAO initial conditions and anomalies on the modeled response to Pinatubo-sized volcanic forcing.", Atmospheric Chemistry and Physics, 23 (24): 15491-15505 [10.5194/acp-23-15491-2023] [Journal Article/Letter]

2023. "On the Remote Impacts of Mid‐Holocene Saharan Vegetation on South American Hydroclimate: A Modeling Intercomparison.", Geophysical Research Letters, 50 (12): [10.1029/2022gl101974] [Journal Article/Letter]

2023. "The Impact of Background ENSO and NAO Conditions and Anomalies on the Modeled Response to Pinatubo-Sized Volcanic Forcing.", , [10.5194/acp-2023-54] [Journal Article/Letter]

2023. "Investigating hydroclimatic impacts of the 168–158 BCE volcanic quartet and their relevance to the Nile River basin and Egyptian history.", Climate of the Past, 19 (1): 249-275 [10.5194/cp-19-249-2023] [Journal Article/Letter]

2022. "Constraining Clouds and Convective Parameterizations in a Climate Model Using Paleoclimate Data.", Journal of Advances in Modeling Earth Systems, 14 (8): [10.1029/2021ms002893] [Journal Article/Letter]

2022. "Clumped‐Isotope Constraint on Upper‐Tropospheric Cooling During the Last Glacial Maximum.", AGU Advances, 3 (4): [10.1029/2022av000688] [Journal Article/Letter]

2022. "Investigating stable oxygen and carbon isotopic variability in speleothem records over the last millennium using multiple isotope-enabled climate models.", Climate of the Past, 18 (7): 1625-1654 [10.5194/cp-18-1625-2022] [Journal Article/Letter]

2022. "Investigating hydroclimatic impacts of the 168–158 BCE volcanic quartet and their relevance to the Nile River basin and Egyptian history.", Climate of the Past, [10.5194/cp-2022-25] [Journal Article/Letter]

2022. "Future Climate Change under SSP Emission Scenarios with GISS‐E2.1.", Journal of Advances in Modeling Earth Systems, 14 (7): e2021MS002871 [10.1029/2021ms002871] [Journal Article/Letter]

2022. "Effects of forcing differences and initial conditions on inter-model agreement in the VolMIP volc-pinatubo-full experiment.", Geoscience Model Development, 15 (5): 2265-2292 [10.5194/gmd-2021-372] [Journal Article/Letter]

2021. "Investigating oxygen and carbon isotopic relationships in speleothem records over the last millennium using multiple isotope-enabled climate models.", Climate of the Past, [10.5194/cp-2021-152] [Journal Article/Letter]

2021. "A data–model approach to interpreting speleothem oxygen isotope records from monsoon regions.", Climate of the Past, 17 (3): 1119-1138 [10.5194/cp-17-1119-2021] [Journal Article/Letter]

2021. "The PMIP4 Last Glacial Maximum experiments: preliminary results and comparison with the PMIP3 simulations.", Climate of the Past, 17 (3): 1065-1089 [10.5194/cp-17-1065-2021] [Journal Article/Letter]

2021. "The Toba supervolcano eruption caused severe tropical stratospheric ozone depletion.", Communications Earth & Environment, 2 (1): 71 [10.1038/s43247-021-00141-7] [Journal Article/Letter]

2021. "Large-scale features of Last Interglacial climate: results from evaluating the lig127k simulations for the Coupled Model Intercomparison Project (CMIP6)–Paleoclimate Modeling Intercomparison Project (PMIP4).", Climate of the Past, 17 (1): 63-94 [10.5194/cp-17-63-2021] [Journal Article/Letter]

2021. "A multi-model CMIP6-PMIP4 study of Arctic sea ice at 127 ka: sea ice data compilation and model differences.", Climate of the Past, 17 (1): 37-62 [10.5194/cp-17-37-2021] [Journal Article/Letter]

2021. "CMIP6 Historical Simulations (1850‐2014) with GISS‐E2.1.", Journal of Advances in Modeling Earth Systems, 13 e2019MS002034 [10.1029/2019ms002034] [Journal Article/Letter]

2020. "Large-scale features and evaluation of the PMIP4-CMIP6 midHolocene simulations.", Climate of the Past, 16 (5): 1847-1872 [10.5194/cp-16-1847-2020] [Journal Article/Letter]

2020. "Comparison of past and future simulations of ENSO in CMIP5/PMIP3 and CMIP6/PMIP4 models.", Climate of the Past, 16 (5): 1777–1805 [10.5194/cp-2019-155] [Journal Article/Letter]

2020. "GISS‐E2.1: Configurations and Climatology.", Journal of Advances in Modeling Earth Systems, 12 (8): [10.1029/2019ms002025] [Journal Article/Letter]

2020. "The PMIP4-CMIP6 Last Glacial Maximum experiments: preliminary results and comparison with the PMIP3-CMIP5 simulations.", Climate of the Past, [10.5194/cp-2019-169] [Journal Article/Letter]

2020. "Large-scale features of Last Interglacial climate: Results from evaluating the ig127k simulations for CMIP6-PMIP4.", , [10.5194/cp-2019-174] [Journal Article/Letter]

2020. "Large-scale features and evaluation of the PMIP4-CMIP6 midHolocene simulations.", Climate of the Past, [10.5194/cp-2019-168] [Journal Article/Letter]

2020. "The Role of the SO Radiative Effect in Sustaining the Volcanic Winter and Soothing the Toba Impact on Climate.", Journal of Geophysical Research: Atmospheres, 125 (2): [10.1029/2019jd031726] [Journal Article/Letter]

2019. "Spatial Shift of Greenland Moisture Sources Related to Enhanced Arctic Warming.", Geophysical Research Letters, 2019GL084633 [10.1029/2019gl084633] [Journal Article/Letter]

2019. "A double bootstrap approach to Superposed Epoch Analysis to evaluate response uncertainty.", Dendrochronologia, 55 119-124 [10.1016/j.dendro.2019.05.001] [Journal Article/Letter]

2019. "Simulated Greenland Surface Mass Balance in the GISS ModelE2 GCM: Role of the Ice Sheet Surface.", Journal of Geophysical Research: Earth Surface, 124 (3): 750-765 [10.1029/2018jf004772] [Journal Article/Letter]

2018. "Assessing the impact of large volcanic eruptions of the last millennium (850–1850 CE) on Australian rainfall regimes.", Climate of the Past, 14 (6): 811-824 [10.5194/cp-14-811-2018] [Journal Article/Letter]

2018. "Multi-model comparison of the volcanic sulfate deposition from the 1815 eruption of Mt. Tambora.", Atmospheric Chemistry and Physics, 18 (3): 2307-2328 [10.5194/acp-18-2307-2018] [Journal Article/Letter]

2017. "The PMIP4 contribution to CMIP6 – Part 3: The last millennium, scientific objective, and experimental design for the PMIP4 past1000 simulations.", Geoscientific Model Development, 10 (11): 4005-4033 [10.5194/gmd-10-4005-2017] [Journal Article/Letter]

2017. "The PMIP4 contribution to CMIP6 – Part 4: Scientific objectives and experimental design of the PMIP4-CMIP6 Last Glacial Maximum experiments and PMIP4 sensitivity experiments.", Geoscientific Model Development, 10 (11): 4035-4055 [10.5194/gmd-10-4035-2017] [Journal Article/Letter]

2017. "The PMIP4 contribution to CMIP6 – Part 2: Two interglacials, scientific objective and experimental design for Holocene and Last Interglacial simulations.", Geoscientific Model Development, 10 (11): 3979-4003 [10.5194/gmd-10-3979-2017] [Journal Article/Letter]

2017. "The PMIP4 contribution to CMIP6 – Part 3: the Last Millennium, Scientific Objective and Experimental Design for the PMIP4 past1000 simulations.", Geoscientific Model Development Discussions, 10 4005-4033 [10.5194/gmd-10-4005-2017] [Journal Article/Letter]

2017. "The PMIP4 contribution to CMIP6 – Part 2: Two Interglacials, Scientific Objective and Experimental Design for Holocene and Last Interglacial Simulations.", Geoscientific Model Development Discussions, 10 3979-4003 [10.5194/gmd-10-3979-2017] [Journal Article/Letter]

2017. "Northern Hemisphere winter warming and summer monsoon reduction after volcanic eruptions over the last millennium.", Journal of Geophysical Research: Atmospheres, 122 (15): 7971-7989 [10.1002/2017jd026728] [Journal Article/Letter]

2017. "European and Mediterranean hydroclimate responses to tropical volcanic forcing over the last millennium.", Geophysical Research Letters, 44 (10): 5104-5112 [10.1002/2017gl073057] [Journal Article/Letter]

2017. "Spatiotemporal variability in the δ18O-salinity relationship of seawater across the tropical Pacific Ocean.", Paleoceanography, 32 (5): 484-497 [10.1002/2016pa003073] [Journal Article/Letter]

2017. "The DeepMIP contribution to PMIP4: experimental design for model simulations of the EECO, PETM, and pre-PETM (version 1.0).", Geoscientific Model Development, 10 (2): 889-901 [10.5194/gmd-10-889-2017] [Journal Article/Letter]

2017. "DeepMIP: experimental design for model simulations of the EECO, PETM, and pre-PETM.", Geoscientific Model Development, 10 889-901 [10.5194/gmd-10-889-2017] [Journal Article/Letter]

2017. "Droughts, floods, and wildfires.", Climate Science Special Report: Fourth National Climate Assessment, Volume I, 231--256 [10.7930/J0CJ8BNN] [Report]

2017. "Temperature changes in the United States.", Climate Science Special Report: Fourth National Climate Assessment, Volume I, 185--206 [10.7930/J0N29V45] [Report]

2017. "Sea level rise.", Climate Science Special Report: Fourth National Climate Assessment, Volume I, 333--363 [10.7930/J0VM49F2] [Report]

2017. "Large-scale circulation and climate variability.", Climate Science Special Report: Fourth National Climate Assessment, Volume I, 161--184 [10.7930/J0RV0KVQ] [Report]

2017. "Potential surprises — compound extremes and tipping elements.", Climate Science Special Report: Fourth National Climate Assessment, Volume I, 411--429 [10.7930/J0GB227J] [Report]

2017. "Climate models, scenarios, and projections.", Climate Science Special Report: Fourth National Climate Assessment, Volume I, 133--160 [10.7930/J0WH2N54] [Report]

2017. "Precipitation change in the United States.", Climate Science Special Report: Fourth National Climate Assessment, Volume I, 207-230 [10.7930/J0H993CC] [Report]

2017. "Our globally changing climate.", Climate Science Special Report: Fourth National Climate Assessment, Volume I, 35-72 [10.7930/J08S4N35] [Report]

2016. "How Did Climate and Humans Respond to Past Volcanic Eruptions?.", Eos, 97 [10.1029/2016EO062599] [Journal Article/Letter]

2016. "Hemispherically asymmetric volcanic forcing of tropical hydroclimate and water isotopologue variability during the last millennium.", Earth System Dynamics Discussions, 7 681-696 [10.5194/esd-7-681-2016] [Journal Article/Letter]

2016. "Role of atmospheric chemistry in the climate impacts of stratospheric volcanic injections.", Nature Geoscience, [10.1038/ngeo2771] [Journal Article/Letter]

2016. "The influence of volcanic eruptions on the climate of tropical South America during the last millennium in an isotope-enabled general circulation model.", Clim. Past, 12 (4): 961-979 [10.5194/cp-12-961-2016] [Journal Article/Letter]

2016. "Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous.", Atmos. Chem. Phys., 16 (6): 3761-3812 [10.5194/acp-16-3761-2016] [Journal Article/Letter]

2016. "A model–model and data–model comparison for the early Eocene hydrological cycle.", Clim. Past, 12 (2): 455-481 [10.5194/cp-12-455-2016] [Journal Article/Letter]

2015. "Late-glacial to late-Holocene shifts in global precipitation delta18O.", Clim. Past, 11 1375-1393 [doi:10.5194/cp-11-1375-2015] [Journal Article/Letter]

2015. "Stability of ENSO and its tropical Pacific teleconnections over the Last Millennium.", Clim. Past, 11 1347-1360 [doi:10.5194/cp-11-1347-2015] [Journal Article/Letter]

2015. "Do responses to different anthropogenic forcings add linearly in climate models?.", Environ. Res. Lett., 10 (10): 104010 [doi:10.1088/1748-9326/10/10/104010] [Journal Article/Letter]

2015. "Laurentide ice-sheet instability during the last deglaciation.", Nature Geosci., 8 (7): 534-537 [doi:10.1038/ngeo2463] [Journal Article/Letter]

2015. "Future climate change under RCP emission scenarios with GISS ModelE2.", J. Adv. Model. Earth Syst., 7 (1): 244-267 [doi:10.1002/2014MS000403] [Journal Article/Letter]

2015. "Southern Laurentide ice-sheet retreat synchronous with rising boreal summer insolation.", Geology, 43 (1): 23-26 [doi:10.1130/G36179.1] [Journal Article/Letter]

2014. "Earliest Holocene south Greenland ice sheet retreat within its late Holocene extent.", Geophys. Res. Lett., 41 (15): 5514-5521 [10.1002/2014GL060800] [Journal Article/Letter]

2014. "Evaluating climate model performance in the tropics with retrievals of water isotopic composition from Aura TES.", Geophys. Res. Lett., 41 (16): 6030-6036 [doi:10.1002/2014GL060572] [Journal Article/Letter]

2014. "CMIP5 historical simulations (1850-2012) with GISS ModelE2.", J. Adv. Model. Earth Syst., 6 (2): 441-477 [10.1002/2013MS000266] [Journal Article/Letter]

2014. "Comparison of forced ENSO-like hydrological expressions in simulations of the preindustrial and mid-Holocene.", J. Geophys. Res. Atmos., 119 (12): 7064-7082 [10.1002/2013JD020961] [Journal Article/Letter]

2014. "Configuration and assessment of the GISS ModelE2 contributions to the CMIP5 archive.", J. Adv. Model. Earth Syst., 6 (1): 141-184 [10.1002/2013MS000265] [Journal Article/Letter]

2014. "Assessing the impact of Laurentide Ice Sheet topography on glacial climate.", Climate of the Past, 10 (2): 487-507 [10.5194/cp-10-487-2014] [Journal Article/Letter]

2014. "Uncertainties in the modelled CO2 threshold for Antarctic glaciation.", Climate of the Past, 10 (2): 451-466 [10.5194/cp-10-451-2014] [Journal Article/Letter]

2014. "Using palaeo-climate comparisons to constrain future projections in CMIP5.", Clim. Past, 10 (1): 221-250 [10.5194/cp-10-221-2014] [Journal Article/Letter]

2014. "Spring-summer temperatures since AD 1780 reconstructed from stable oxygen isotope ratios in white spruce tree-rings from the Mackenzie Delta, northwestern Canada.", Clim Dyn, 42 (3-4): 771-785 [10.1007/s00382-013-1674-3] [Journal Article/Letter]

2013. "Modeling insights into deuterium excess as an indicator of water vapor source conditions.", J. Geophys. Res. Atmos., 118 (2): 243-262 [10.1029/2012JD017804] [Journal Article/Letter]

2013. "Model sensitivity to North Atlantic freshwater forcing at 8.2 ka.", Climate of the Past, 9 (2): 955-968 [10.5194/cp-9-955-2013] [Journal Article/Letter]

2012. "A model–data comparison for a multi-model ensemble of early Eocene atmosphere–ocean simulations: EoMIP.", Climate of the Past, 8 (5): 1717-1736 [10.5194/cp-8-1717-2012] [Journal Article/Letter]

2012. "A Tropospheric Emission Spectrometer HDO/H₂O retrieval simulator for climate models.", Atmos. Chem. Phys., 12 (21): 10485-10504 [10.5194/acp-12-10485-2012] [Journal Article/Letter]

2012. "The influence of Indian Ocean atmospheric circulation on Warm Pool hydroclimate during the Holocene epoch.", J Geophys Res, 117 (D19): D19108 [10.1029/2012JD018060] [Journal Article/Letter]

2012. "Linking the 8.2 ka event and its freshwater forcing in the Labrador Sea.", Geophys Res Lett, 39 (18): L18703 [10.1029/2012GL053047] [Journal Article/Letter]

2011. "Model, proxy and isotopic perspectives on the East African Humid Period.", Earth Planet Sci Lett, 307 (1-2): 103-112 [10.1016/j.epsl.2011.04.038] [Journal Article/Letter]

2011. "Sensitivity of seawater oxygen isotopes to climatic and tectonic boundary conditions in an early Paleogene simulation with GISS ModelE-R.", Paleoceanography, 26 (4): PA4203 [10.1029/2010PA002025] [Journal Article/Letter]

2011. "Water isotopologues as a quantitative paleosalinity proxy.", Paleoceanography, 26 (3): PA3225 [10.1029/2010PA002043] [Journal Article/Letter]

2011. "High-resolution stalagmite reconstructions of Australian–Indonesian monsoon rainfall variability during Heinrich stadial 3 and Greenland interstadial 4.", Earth and Planetary Science Letters, 303 (1-2): 133-142 [10.1016/j.epsl.2010.12.048] [Journal Article/Letter]

2011. "The anomalous winter of 1783-1784: Was the Laki eruption or an analog of the 2009-2010 winter to blame?.", Geophysical Research Letters, 38 (5): L05706 [10.1029/2011GL046696] [Journal Article/Letter]

2011. "Relating tropical ocean clouds to moist processes using water vapor isotope measurements.", Atmos. Chem. Phys., 11 (2): 741-752 [10.5194/acp-11-741-2011] [Journal Article/Letter]

2010. "Water vapour source impacts on oxygen isotope variability in tropical precipitation during Heinrich events.", Climate of the Past, 6 (3): 325-343 [10.5194/cp-6-325-2010] [Journal Article/Letter]

2009. "Potential biases in inferring Holocene temperature trends from long-term borehole information.", Geophysical Research Letters, 36 (5): L05708 [10.1029/2008GL036354] [Journal Article/Letter]

2009. "Sources of Holocene variability of oxygen isotopes in paleoclimate archives.", Climate of the Past, 5 (3): 441-455 [10.5194/cp-5-441-2009] [Journal Article/Letter]

2009. "Climate sensitivity to Arctic seaway restriction during the early Paleogene.", Earth Planet Sci Lett, 286 (3-4): 576-585 [10.1016/j.epsl.2009.07.026] [Journal Article/Letter]

2009. "Surface-melt driven Laurentide Ice Sheet retreat during the early Holocene.", Geophys Res Lett, 36 (24): L24502 [10.1029/2009GL040948] [Journal Article/Letter]

2008. "Possible evidence for wet Heinrich phases in tropical NE Australia: the Lynch's Crater deposit.", Quaternary Science Reviews, 27 (5-6): 468-475 [10.1016/j.quascirev.2007.11.006] [Journal Article/Letter]

2008. "Ensemble, water isotope-enabled, coupled general circulation modeling insights into the 8.2 ka event.", Paleoceanography, 23 (3): PA3207 [10.1029/2008PA001610] [Journal Article/Letter]

2008. "Subtropical Atlantic salinity variability and Atlantic meridional circulation during the last deglaciation.", Geology, 36 (12): 991-994 [10.1130/G25080A.1] [Journal Article/Letter]

2008. "Rapid early Holocene deglaciation of the Laurentide ice sheet.", Nature Geosci, 1 (9): 620-624 [10.1038/ngeo285] [Journal Article/Letter]

2007. "Water isotope expressions of intrinsic and forced variability in a coupled ocean-atmosphere model.", J. Geophys. Res., 112 (D10): D10103 [10.1029/2006JD007781] [Journal Article/Letter]

2007. "Seawater isotope constraints on tropical hydrology during the Holocene.", Geophys Res Lett, 34 (13): L13701 [10.1029/2007GL030017] [Journal Article/Letter]

2007. "Surface currents in the western North Atlantic during the Last Glacial Maximum.", Geochemistry, Geophysics, Geosystems, 8 (1): Q01N09 [10.1029/2006GC001371] [Journal Article/Letter]

2006. "Past and future polar amplification of climate change: climate model intercomparisons and ice-core constraints.", Clim Dyn, 26 (5): 513-529 [10.1007/s00382-005-0081-9] [Journal Article/Letter]

2006. "Consistent simulations of multiple proxy responses to an abrupt climate change event.", Proceedings of the National Academy of Sciences, 103 (4): 837-842 [10.1073/pnas.0510095103] [Journal Article/Letter]

2006. "Global gridded data set of the oxygen isotopic composition in seawater.", Geophys Res Lett, 33 (12): L12604 [10.1029/2006GL026011] [Journal Article/Letter]

2005. "Mid-Holocene NAO: A PMIP2 model intercomparison.", Geophysical Research Letters, 32 (16): L16707 [10.1029/2005GL023596] [Journal Article/Letter]

2004. "Oxygen isotopic composition of Globorotalia truncatulinoides as a proxy for intermediate depth density.", Paleoceanography, 19 (4): PA4025 [10.1029/2004PA001045] [Journal Article/Letter]

Non-Refereed

2016. "How Will Sea Ice Loss Affect the Greenland Ice Sheet?.", Eos, 97 (9): 10 [10.1029/2016eo047961] [Other]

2015. "Volcanoes and Climate.", PAGES -- Past Global Changes, 23 (2): 41-84 [Full Text] [Magazine]

2005. "The Goldilocks abrupt climate change event.", Quaternary Science Reviews, 24 (10-11): 1109-1110 [10.1016/j.quascirev.2005.01.015] [Journal Article/Letter]

Grants

B1-ERC-4-OCEANS: Human History of Marine Life - B1-ERC - Awarded: 2022-08-01


NSF-P2C2: Collaborative Research: Constraining cloud and convective parameterizations using paleoclimate data assimilation; PI M Griffiths; coPIs J. Tierney and G. Elsaesser - NSF - Awarded: 2022-07-01


Growth versus Suppression of Atmospheric Rivers: Building New Theory by Leveraging CYGNSS Winds and NASA-GISS ModelE

NNH20ZDA001N-CYGNSS:A.27 CYGNSS Competed Science Team - NASA-20-CYGNSS20-0022: - Awarded: 2021-05-03


Dates: 2021-05-03  - 2024-05-02

Volcanism, Hydrology and Social Conflict: Lessons from Hellenistic and Roman-Era Egypt and Mesopotamia

NSF-CNH - NSF - Awarded: 2018-09-01


Dates: 2018-09-01  - 2024-03-31

Amount 1.3 million

Understanding and quantifying the links between ice sheet and glacial albedo, surface mass balance and atmospheric fluxes through improved NASA GISS-E2 simulations

16-MAP16-NNH16ZDA001N-MAP: - NASA-Modeling, Analysis, and Prediction - Awarded: 2017-07-15


Dates: 2017-07-15  - 2021-07-14

What should NASA do in case of a major volcanic eruption?, co-PI P. Colarco (GSFC)

Science and Mission Directorate - NASA - Awarded: 2015-07-01


Dates: 2015-10-01  - 2016-09-30

Volcanic Impacts on Climate and Society, Inaugural Working Group meeting

PAGES - Past Global Changes - Awarded: 2016-01-06


Dates: 2016-01-01  - 2016-07-31

Satellite and model constraints on water cycling responses to MJO and ENSO using water isotopes: Renewal

PI: NNH13ZDA001N-NEWS - NASA-NEWS - Awarded: 2014-08-20


Dates: 2014-11-01  - 2017-10-31

An LDEO/GISS Workshop: Improving the understanding of the impact of volcanic events. coI: R. D’Arrigo

Climate Center, LDEO/GISS - Columbia University - Awarded: 2013-10-31


Dates:  - 

“Sensitivity of Climate Variability to Anthropogenic and Natural Drivers during the Last Millennium”

PI: NOAA C2D2 NA10OAR4310126 - NOAA-C2D2 - Awarded: 2010-08-01


Dates: 2008-08-01  - 2014-07-31

“Collaborative Research: Multi-scale analysis of Stable Isotope-climate relationships in tropical proxy records” PI: M. Vuille

Co-PI: NSF P2C2 NSF-AGS-1003690 - NSF-P2C2 - Awarded: 2010-08-01


Dates:  - 

Workshop Award: “Polar Amplification of Greenhouse Climates.”

PI NSF-ADVANCE - NSF-Advance - Awarded: 2009-08-01


Dates:  - 

“Collaborative Research: A New Method for Understanding Mechanisms of Ice Sheet Demise” Co-PI: A.E. Carlson

Co-PI: NSF-ATM 07-53660 - NSF-Atmospheres - Awarded: 2008-08-01


Dates: 2008-08-01  - 2011-12-01

Teaching Experience

Mentor for Hayoung Bong, NASA Postdoctoral Program

Mentor for Riovie Ramos, William Patterson University Postdoc

Mentor for Ram Singh, Columbia CCSR (GISS) Postdoc

Mentor for Jesse Nussbaumer, NASA Postdoctoral Program

Mentor for Patrick Alexander, NASA Postdoctoral Program

__

Humans and the Carbon Cycle -- guest lecturer, Spring 2013

__

Co-Supervised Carlos Ordaz of City College of New York for his Ph.D. thesis with James Booth

Mentored Yilin Zhang, Stefan Riady Fellowship, NTU Singapore with Xianfeng Wang

Co-Supervised Chris Colose of University of Albany for his Ph.D. thesis with Mathias Vuille

Co-Supervised Chris D. Roberts of Cambridge University for his Ph.D. thesis with Aradhna Tripati

Co-Supervised Sophie C. Lewis of Australian National University for her Ph.D. thesis with Jeanette Lindsay and Michael Gagan

Co-Supervised David J. Ullman of the University of Wisconsin, Madison for his Ph.D. thesis with Anders C. Carlson

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Mentored High School Teacher Sangmin Pak, Queens, New York, Ridgewood High School

Mentored High School Teacher Trevor Brown, Bronx, New York, High School for Law and Community Service

Mentored High School Teacher Kaitlin Tucker, Bronx, New York, Knowledge and Power Preparatory Academy International High School

Mentored High School Teacher John Garvey, Bronx, New York, Community School for Social Justice

Mentored High School Teacher Nicole Dulaney, New York City, Hilcrest High School

Selected Public Outreach

USGCRP CCSR, NCA4

2016 - Present

Dr. LeGrande worked on the USGCRP Climate Science Special Report (CSSR), which will be used in the Fourth National Climate Assessment.

EOA 2016

2014 - Present

Dr. LeGrande worked under NASA (Anne Thompson) and DoE (Dorothy Koch) to develop the Earth Observational Assessment (EOA) 2016 Paleoclimate section with Eugene Wahl and Thomas Cronin.

Climate Change Research Initiative

2014 - Present

Climate Change Research Initiative

The NASA GISS Climate Change Research Initiative — CCRI — is a summer internship opportunity for high school and undergraduate students as well as a year-long STEM engagement opportunity for educators and graduate students. Students and educators work directly with NASA scientists on NASA research projects associated with the science related to climate change.

LDEO-Columbia University Summer Internship

2011 - Present

Summer Intern Programs for Undergraduates

The Lamont Summer Intern Program for undergraduates from U.S. colleges and universities provides a summer research experience in Earth and ocean sciences. The program features a hands-on research project under the supervision of a Columbia-affiliated scientist, as well as special lectures, workshops and fieldtrips. Visit the program page for details and access to the online application.

Intrepid GOALS mentor

2015 - Present

The GOALS (Greater Opportunities Advancing Leadership and Science) for Girls program aims to increase the presence of women in STEM (science, technology, engineering and math) fields. We do this by providing female students with a positive influence, increasing their confidence and improving their attitudes toward STEM topics, equipping them with key skills and resources needed for success in STEM fields, and encouraging the pursuit of STEM-centric careers and studies.

Year-round programs, which include internships, weekend forums and the GOALS for Girls Summer Intensive program, offer female students, families, and their schools various pathways to connect to the Intrepid Museum and STEM opportunities.

Dulaney, N., 2018: Earth's Energy Budgets. Applied Research STEM Curriculum Unit Portfolio. Mentor: A. LeGrande CCRI Program: M. Pearce

2020 - Present

Free, NGSS, NYS Regents 3 week High School Education Unit (16.8 MB PDF)

1 of 3 in Series by N. Dulaney

Dulaney, N., 2021: Changes in Climate and Wildfires. Applied Research STEM Curriculum Unit Portfolio.

2021 - Present

Free, NGSS, NYS Regents 6 week High School Education Unit (5.0 MB PDF)

2 of 3 in series by Dulaney.

Dulaney, N., 2019: Future Temperature Projections. Applied Research STEM Curriculum Unit Portfolio. Mentor: A. LeGrande CCRI Program: M. Pearce

2020 - Present

Free, NGSS, NYS Regents 3 week Free High School Education Unit  (7.3 MB PDF)

3 of 3 in Series by N. Dulaney

Contact Us

For general inquiries about the Sciences and Exploration Directorate.

Jocelyn Lynch

Project Support Specialist

301-286-6066 jocelyn.m.lynch@nasa.gov
Ellie Jeffries

Project Support Specialist

301-286-6066 ellie.jeffries@nasa.gov
Technical issues with this website may be reported to ben.pelletier@nasa.gov.
General inquiries about the scientific programs at NASA's Goddard Space Flight Center may be directed to the Center Office of Communications at 1.301.286.8955.