About

Dr. Marcus Lofverstrom is an Associate Professor in the Department of Geosciences at the University of Arizona. He received his PhD in meteorology from Stockholm University and completed postdoctoral research at the National Center for Atmospheric Research (NCAR) in Boulder, CO. His research uses numerical modeling to investigate climate variability and change on regional to hemispheric scales, with a particular emphasis on planetary waves, jetstream and storm-track dynamics, and two-way feedbacks and interactions between ice sheets and the large-scale circulation. At the University of Arizona, he teaches undergraduate and graduate courses in scientific programming, numerical modeling, and climate dynamics.

Research topics

• Oceanography
• Geology
• Climatology
• Environmental science
• Atmospheric sciences
• Geography
• Meteorology
• Ecology
• Chemistry
• Biology
• Physics
• Mineralogy
• Physical geography
• Geomorphology

Selected publications

• Recent intensification of eastern Pacific ENSO is unprecedented across the last millennium

  2026-04-30

  articleOpen access

  The Pacific El Niño-Southern Oscillation (ENSO) phenomenon generates climate extremes that endanger ecosystems, infrastructure, and human well-being worldwide. The response of this system to climate warming is poorly constrained, due to data scarcity and climate model biases, making projections of future climate hazards uncertain. The geochemistry of Galápagos coral skeletons across the past millennium reveals an unprecedented increase in interannual variability of sea surface temperature in the eastern equatorial Pacific that has emerged above pre-industrial levels and exceeds simulated natural variability. This increase parallels the rise in global temperature and results from stronger El Niño events. Central Pacific coral data also show increased variability, although less distinctly than in Galápagos. Our results provide long-term context for understanding ENSO variability trends, with troubling implications for future climate extremes.

  PublisherDOI

• CMIP6 Models under the Lens: Evaluating the Representation of the Tropical South American Summer Precipitation

  Journal of Climate · 2026-02-09

  article

  Abstract Tropical South American summer precipitation is primarily controlled by the intensity and position of the South American monsoon and the intertropical convergence zone, both of which respond to sea surface temperature anomalies over the surrounding tropical oceans. Our analysis examines how well contemporary, high-complexity Earth system models from the Coupled Model Intercomparison Project phase 6 (CMIP6) simulate the summer precipitation distribution and its interannual variability under preindustrial climate conditions. Specifically, we investigate how El Niño–Southern Oscillation (ENSO) and Atlantic Niño—two major zonal modes of variability in the tropical ocean—shape tropical South American precipitation through remote atmospheric teleconnections. The quality of the simulated climatological mean state and interannual variability across models is primarily evaluated using pattern correlations with the fifth generation European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis (ERA5) product. The three models with the highest and the three models with the lowest field correlation with the ERA5 reference are selected for a more detailed study of their representation of major modes of variability and associated teleconnection patterns. We show that models with large discrepancies in the location and abundance of core monsoon precipitation also typically fail to accurately represent atmospheric deep convection and teleconnections associated with the zonal modes. Differences in the ability to simulate South American summer precipitation, even under preindustrial forcings, emphasize the importance of selecting an appropriate model for studying the regional hydroclimate. Our study further calls for future research using high-resolution models that explicitly resolve deep convection to realistically capture South American monsoon rainfall. Significance Statement Tropical South America receives abundant rainfall from December through February, which is dominated by the South American monsoon system and the deep convection in the intertropical convergence zone. Naturally occurring climate modes in the surrounding tropical oceans, such as El Niño–Southern Oscillation and Atlantic Niño, also drive large variability in summer rainfall. Accurately representing how rainfall over tropical South America responds to modes of climate variability in preindustrial simulations is essential for evaluating the robustness and realism of climate models. Our study shows that models with more realistic atmospheric convection (upward vertical motion in the lower to midtroposphere) better depict the observed rainfall patterns and year-to-year changes over tropical South America, including the rainfall patterns shaped by the modes of variability. Models that better replicate these influences can be instrumental not only in understanding the future of South American rainfall but also in attribution studies of extreme events like droughts and floods.

  PublisherDOI

• Towards a Realistic Representation of Katabatic Storms in Greenland in Reanalysis Data and Global Earth System Models

  Journal of Geophysical Research Atmospheres · 2026-01-25

  article1st authorCorresponding

  Abstract Katabatic storms in southeastern Greenland are fierce, density‐driven, downslope wind events with substantial implications for the local and downstream weather conditions and climate. This study presents a detailed assessment of their representation across three generations of global reanalysis products (ERA5, ERA‐Interim, and ERA40) from the European Centre for Medium‐Range Weather Forecasts, paired with a hierarchy of simulations at different grid resolutions with the Community Earth System Model version 2 (CESM2). Using the high‐resolution (2.5‐km resolution) Copernicus Arctic Regional Reanalysis (CARRA) as a benchmark, we find that the global reanalysis data sets systematically underestimate wind speeds (around 30% in ERA5 and 50% in ERA‐Interim and ERA40) and fail to capture key structural features of these regional storms. Similar deficiencies are observed in CESM2 simulations when using standard latitude‐longitude grids at 1–2 horizontal resolutions, which is a common model configuration used in recent iterations of the Coupled Model Intercomparison Projects. Variable‐resolution configurations in CESM2 with enhanced representation of the Greenland topography demonstrate a marked improvement in capturing the strength and structure of these regional storms. Sensitivity simulations further confirm that steeper ice‐sheet margins (better resolved at higher spatial resolution) are crucial for accurately representing katabatic acceleration. These findings underscore the importance of spatial resolution and realistic topographic representation in simulating local climate extremes. Accurately capturing such events is vital not only for understanding modern climate dynamics on and around the polar ice sheets, but likely also for simulating realistic ice sheet/Earth system interactions in glacial climates of the past.

  PublisherDOI

• El Niño events recorded by redox sensitive trace elements in sedimentary records from Genovesa Lake, Galápagos

  The Science of The Total Environment · 2026-04-20

  article
  PublisherDOI

• Rapid decline and mortality of a Pleistocene-aged forest now submerged in the northern Gulf of Mexico, USA

  npj Climate and Atmospheric Science · 2025-02-20

  articleOpen access

  The Gulf and Atlantic Coastal Plains of the southern United States are characterized by a wide continental shelf that was subaerially exposed for ca. 80,000 years during glacial-interval marine regressions and transgressions. Given their present submergence, little is known about the vegetation dynamics, particularly at annual time scales, of these formerly terrestrial sites due to erosional processes associated with marine transgressions. Here, we present an annually resolved and well-replicated 489-year tree-ring chronology from macrobotanical specimens—anatomically identified as Taxodium distichum (L.) Rich.—collected in situ from a recently exposed submerged forest in 18 m water depth in the northern Gulf of Mexico. This chronology not only reveals historical vegetation dynamics at annual resolutions during Marine Isotope Stages 3–5a, but it also captures a catastrophic mortality event likely connected to intense storm activity, perhaps driven by freshwater fluxes from Heinrich events. Our findings are supported by coupled climate model simulations from the last glaciation, providing new insights into the environmental history of the southeastern US coastal regions.

  PublisherOA PDFDOI

• Ice-sheet topography changes in North America affect teleconnection patterns on glacial time scales

  2025-03-15

  preprintOpen accessCorresponding

  The topography of the Laurentide Ice Sheet (LIS) during glacial periods, particularly the Last Glacial Maximum (LGM), played a pivotal role in shaping atmospheric circulation and teleconnection patterns. This study investigates the impact of LIS elevation changes on global atmospheric dynamics using fully coupled paleoclimate simulations with the isotope-enabled Community Earth System Model (CESM) version 1.2. Previous studies have shown that a higher LIS elevation significantly amplifies Arctic warming, reducing the equator-to-pole temperature gradient and influencing jet streams and stationary waves (Liakka & Lofverstrom, 2018 ; Beghin et al., 2014 ; Lofverstrom et al., 2014). This mechanism may also extend to the Southern Hemisphere, affecting teleconnection pathways.By systematically modifying LIS elevation, we explore its role in altering large-scale atmospheric circulation features such as the Intertropical Convergence Zone (ITCZ), Southern Annular Mode (SAM), and Walker circulation, as well as modes of variability including El Niño–Southern Oscillation (ENSO). We show the critical influence of LIS topography on global teleconnections and how ice sheet dynamics shaped glacial climate variability and atmospheric feedbacks.

  PublisherDOI

• Surface mass balance and climate of the Last Glacial Maximum Northern Hemisphere ice sheets: simulations with CESM2.1

  Climate of the past · 2024-01-24 · 6 citations

  articleOpen accessSenior author

  Abstract. The Last Glacial Maximum (LGM, from ∼26 to 20 ka BP) was the most recent period with large ice sheets in Eurasia and North America. At that time, global temperatures were 5–7 ∘C lower than today, and sea level ∼125 m lower. LGM simulations are useful to understand earth system dynamics, including climate–ice sheet interactions, and to evaluate and improve the models representing those dynamics. Here, we present two simulations of the Northern Hemisphere ice sheet climate and surface mass balance (SMB) with the Community Earth System Model v2.1 (CESM2.1) using the Community Atmosphere Model v5 (CAM5) with prescribed ice sheets for two time periods that bracket the LGM period: 26 and 21 ka BP. CESM2.1 includes an explicit simulation of snow/firn compaction, albedo, refreezing, and direct coupling of the ice sheet surface energy fluxes with the atmosphere. The simulated mean snow accumulation is lowest for the Greenland and Barents–Kara Sea ice sheets (GrIS, BKIS) and highest for British and Irish (BIIS) and Icelandic (IcIS) ice sheets. Melt rates are negligible for the dry BKIS and GrIS, and relatively large for the BIIS, North American ice sheet complex (NAISC; i.e. Laurentide, Cordilleran, and Innuitian), Scandinavian ice sheet (SIS), and IcIS, and are reduced by almost a third in the colder (lower temperature) 26 ka BP climate compared with 21 ka BP. The SMB is positive for the GrIS, BKIS, SIS, and IcIS during the LGM (26 and 21 ka BP) and negative for the NAISC and BIIS. Relatively wide ablation areas are simulated along the southern (terrestrial), Pacific and Atlantic margins of the NAISC, across the majority of the BIIS, and along the terrestrial southern margin of the SIS. The integrated SMB substantially increases for the NAISC and BIIS in the 26 ka BP climate, but it does not reverse the negative sign. Summer incoming surface solar radiation is largest over the high interior of the NAISC and GrIS, and minimum over the BIIS and southern margin of NAISC. Summer net radiation is maximum over the ablation areas and minimum where the albedo is highest, namely in the interior of the GrIS, northern NAISC, and all of the BKIS. Summer sensible and latent heat fluxes are highest over the ablation areas, positively contributing to melt energy. Refreezing is largest along the equilibrium line altitude for all ice sheets and prevents 40 %–50 % of meltwater entering the ocean. The large simulated melt for the NAISC suggests potential biases in the climate simulation, ice sheet reconstruction, and/or highly non-equilibrated climate and ice sheet at the LGM time.

  PublisherDOI

• Tropical mountain ice core  : A Goldilocks indicator for global temperature change

  2024-03-08

  preprintOpen accessCorresponding

   Tropical mountain ice core : A Goldilocks indicator for global temperature change   Zhengyu Liu1,2,3, , Yuntao Bao1, Lonnie G. Thompson3,4, Ellen Mosley-Thompson1,3,  Tabor Clay5, Guang J. Zhang6, Mi Yan2, Marcus Lofverstrom7, Isabel Montanez8,  Jessica Oster9  1.      Department of Geography, The Ohio State University, Columbus, OH 2.      School of Geography Science, Nanjing Normal University, Nanjing, China. 3.      Byrd Polar and Climate Research Center, The Ohio State University, Columbus, OH 4.      School of Earth Sciences, The Ohio State University, Columbus, OH 5.      Department of Earth Sciences, University of Connecticut, Storrs, CT 6.      Scripps Institute of Oceanography, University of California San Diego, San Diego, CADepartment of Geosciences, University of Arizona, Tucson, AZ Department of Earth and Planetary Sciences, University of California–Davis, Davis, CA Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, TN  Very high tropical alpine ice coresprovide a distinct paleoclimate record for climate changes in the middle and upper troposphere. However, the climatic interpretation of a key proxy, the stable water oxygen isotopic ratio in ice cores (), remains an outstanding problem. Here, combining proxy records with climate models, modern satellite measurements and radiative-convective equilibrium theory, we show that the tropical  is an indicator of the temperature of the middle and upper troposphere, with a glacial cooling of -7.35+-1.1oC (66% CI). Moreover, it severs as a “Goldilocks-type” indicator of global mean surface temperature change, providing the first estimate of glacial stage cooling that is independent of marine proxies as -5.9+-1.2oC. Combined with all estimations available gives the maximum likelihood estimate of glacial cooling as -5.85+10.51oC .  

  PublisherDOI

• Reconstructing the coupled Greenland Ice Sheet–climate evolution during the Last Interglacial warm period

  2024-03-09

  preprintOpen accessSenior authorCorresponding

  During the Last Interglacial (LIG), approximately 130-118 thousand years ago (ka), the Arctic experienced relative warmth and global sea levels considerably higher than modern.  While this interval is thus considered key for understanding long-term ice–climate feedbacks under warm-state climate conditions, large uncertainties remain surrounding i. the magnitude and spatial expression of LIG global temperature change, ii. the relative contributions of the Antarctic vs. Greenlandic Ice Sheets (GrIS) to LIG sea level rise, and iii. the sensitivity of the GrIS to centennial- to millennial-scale ocean-atmospheric forcing.  Here, we present, to our knowledge, a first attempt at reconstructing the coupled GrIS–climate evolution during the LIG using an internally consistent offline “paleoclimate data assimilation” approach.  Our methodology combines a newly compiled database of nearly 400 chronologically consistent marine geochemical and ice sheet-derived climate-proxy records (spanning 250 sites globally) with recently developed, state-of-the-art transient simulations of the LIG using the coupled Community Earth System Model v2 featuring an interactive Community Ice Sheet Model v2 (CESM2-CISM2).  Our preliminary assimilations suggest LIG peak global mean surface warming of +0.1-0.5˚C (±2 range) above the pre-industrial state, arising from enhanced and widespread (>2-5˚C) high Arctic warming.  Leveraging our CESM2-coupled CISM2 results, we further identify a max GrIS contribution of 2.0 (±0.6) meters of sea level rise equivalent at around 125 ka, nearly ~two millennia after peak LIG climate forcing.  These initial results provide a new proxy-model integration framework for reconciling past GrIS contributions to global sea level rise and benchmark the potential long-term sensitivity of the GrIS to ongoing Arctic warming.

  PublisherDOI

• North Atlantic meltwater during Heinrich Stadial 1 drives wetter climate with more atmospheric rivers in western North America

  Science Advances · 2023-11-17 · 11 citations

  articleOpen access

  Atmospheric rivers (ARs) bring concentrated rainfall and flooding to the western United States (US) and are hypothesized to have supported sustained hydroclimatic changes in the past. However, their ephemeral nature makes it challenging to document ARs in climate models and estimate their contribution to hydroclimate changes recorded by time-averaged paleoclimate archives. We present new climate model simulations of Heinrich Stadial 1 (HS1; 16,000 years before the present), an interval characterized by widespread wetness in the western US, that demonstrate increased AR frequency and winter precipitation sourced from the southeastern North Pacific. These changes are amplified with freshwater fluxes into the North Atlantic, indicating that North Atlantic cooling associated with weakened Atlantic Meridional Overturning Circulation (AMOC) is a key driver of HS1 climate in this region. As recent observations suggest potential weakening of AMOC, our identified connection between North Atlantic climate and northeast Pacific AR activity has implications for future western US hydroclimate.

  PublisherDOI

Frequent coauthors

• Bette L. Otto‐Bliesner

  NSF National Center for Atmospheric Research

  34 shared

• William H. Lipscomb

  NSF National Center for Atmospheric Research

  29 shared

• Katherine Thayer‐Calder

  NSF National Center for Atmospheric Research

  21 shared

• Johan Liakka

  Swedish Nuclear Fuel and Waste Management (Sweden)

  21 shared

• Esther C. Brady

  NSF National Center for Atmospheric Research

  20 shared

• Juan M. Lora

  Planetary Science Institute

  20 shared

• Johan Klemån

  Stockholm University

  17 shared

• William J. Sacks

  NSF National Center for Atmospheric Research

  16 shared