About

My group uses theory, numerical models and observations to understand the terrestrial water cycle, and its relation to weather and climate over land. We are particularly interested in aspects of weather and climate that are unique to land, compared with oceans. For example, land can dry out, whereas the ocean is always saturated. One common theme in our research is understanding the effects of water-limitation on evapotranspiration over land, and consequent changes to the surface energy balance, atmospheric boundary layer, and convective precipitation.

Research topics

• Computer Science
• Geology
• Environmental science
• Atmospheric sciences
• Mathematics
• Meteorology
• Ecology
• Remote sensing
• Climatology
• Geography
• Cartography

Selected publications

• Daily surface flux equilibrium (SFE) ET across CONUS

  Zenodo (CERN European Organization for Nuclear Research) · 2026-03-12

  datasetOpen access

  Daily, 4km estimates of surface flux equilibrium (SFE) ET across CONUS from "Triple collocation validates CONUS-wide evapotranspiration inferred from atmospheric conditions, McCormick et al. (In Minor Revision), Hydrology and Earth System Sciences.

  PublisherDOI

• Impacts of Glacial Isostatic Adjustment on Antarctic Subglacial Water Routing since the Last Glacial Maximum

  Durham Research Online (Durham University) · 2026-04-21

  articleOpen accessSenior author

  The bedrock beneath the Antarctic Ice Sheet has experienced widespread viscoelastic deformation as a response to ice-sheet changes from the Last Glacial Maximum (LGM) to present day. The combined changes of the ice sheet and the bedrock most likely had impacted subglacial water routes. Using the evolution of bedrock elevation simulated with two coupled ice-sheet and glacial isostatic adjustment (GIA) models, we explore changes to the subglacial water routes from the LGM to the present day. We explore the sensitivity of our results to bed roughness by repeating the calculations using ten topographic realizations, and estimate the relative impacts of changes in the bedrock elevation and the ice surface slope. Our results show that bedrock elevation changes of up to ∼400 m likely led to a large enough change in tilt of the bedrock, such that subglacial water routing during the last deglacial phase likely differed significantly from patterns inferred at present day. The impact of GIA on subglacial flow paths is thus non-negligible and should be accounted for in reconstructions of ancient subglacial hydrology and studies of past sediment provenance.

  Publisher

• Bulk Radiative‐Convective Equilibrium Is Common Over Mid‐Latitude Land

  Geophysical Research Letters · 2026-02-24

  articleOpen accessCorresponding

  Abstract Radiative‐convective equilibrium (RCE) is commonly used as an approximation of the time‐ and space‐averaged tropical atmosphere. We examine two reanalyses to assess the extent to which column‐integrated radiative cooling balances convective heating (“bulk RCE”) in the tropics and at higher latitudes. Our analysis shows that bulk RCE is a reasonable approximation of the tropics over ocean, but not land. Surprisingly, bulk RCE is often a reasonable approximation in mid‐latitudes, especially over land. These findings are explained by a simple argument. Over land, the ground heat flux is small, and bulk RCE arises when the top‐of‐atmosphere net radiative flux is small, which occurs in mid‐latitudes. Over ocean, the same mechanism applies but the ocean heat flux can be substantial and causes deviations relative to land. We conclude that bulk RCE is a surprisingly useful approximation of mid‐latitude land climate, which permits the development of simple theory for land climate, more broadly.

  PublisherDOI

• Robust Critical Temperature Projections Reveal Diminishing Heat Safety Margins Under Global Warming

  2026-03-13

  articleOpen accessSenior author

  Uncompensable heat stress (UHS) occurs when human thermoregulation fails to maintain a stable core temperature, posing severe health risks. While previous studies emphasize humidity’s role in future heat stress, we introduce Critical Temperature Margin (CTM) - the buffer between ambient temperature and critical temperature causing UHS - to quantify heat safety under climate change. The CTM is based on human energy balance equations considering a variety of climate factors and key human physiological limits.Using ERA5 data (1980-2023) and CMIP6 projections, we quantify future trends in CTM under different radiation environments and classify heat stress by dominant mechanisms: dry heat (sensible heat and radiative components) and moist heat (evaporative component). Our analysis reveals that future UHS changes are primarily driven by increasing dry heat contribution associated with rising temperature and longwave radiation, while humidity effects of rising saturation vapor pressure and declining relative humidity during extreme events largely cancel out. Our key findings show: (1) CTM diminishes by -2.4°C per degree of global warming (-0.8°C locally) on average; (2) increasing prevalence of dry heat dominated regions over past 40 years; (3) outdoor conditions experience more dry heat stress than indoors; (4) sweat evaporation constraints on moist heat stress remain nearly constant, contradicting assumptions that humidity dominates future heat stress.We also find that human settlements historically avoided thermally challenging regions. However, diminishing CTM threatens millions of world populations, particularly outdoor workers in tropical and subtropical areas who will face similar evaporative cooling capacity but increasing radiative and dry heat loads. Typical moist-heat dominated regions such as India, Sahel, Southeast U.S., East China, Northern Australia will be subject to more than 50% dry heat in outdoor conditions.These findings clarify the ongoing humidity debate in heat-health research. Our results support targeted mitigation strategies: increased ventilation for moist heat, shade for radiation, and active cooling for dry heat. Our robust projection of the CTM provides critical insights for public health adaptation planning as thermal safety margins continue shrinking globally.

  PublisherDOI

• Impacts of Glacial Isostatic Adjustment on Antarctic Subglacial Water Routing Since the Last Glacial Maximum

  Journal of Geophysical Research Earth Surface · 2026-05-01

  articleOpen accessSenior author

  Abstract The bedrock beneath the Antarctic Ice Sheet has experienced widespread viscoelastic deformation as a response to ice‐sheet changes from the Last Glacial Maximum (LGM) to present day. The combined changes of the ice sheet and the bedrock most likely had impacted subglacial water routes. Using the evolution of bedrock elevation simulated with two coupled ice‐sheet and glacial isostatic adjustment (GIA) models, we explore changes to the subglacial water routes from the LGM to the present day. We explore the sensitivity of our results to bed roughness by repeating the calculations using 10 topographic realizations, and estimate the relative impacts of changes in the bedrock elevation and the ice surface slope. Our results show that bedrock elevation changes of up to ∼400 m likely led to a large enough change in tilt of the bedrock, such that subglacial water routing during the last deglacial phase likely differed significantly from patterns inferred at present day. The impact of GIA on subglacial flow paths is thus non‐negligible and should be accounted for in reconstructions of ancient subglacial hydrology and studies of past sediment provenance.

  PublisherDOI

• Large Overestimation of Projected Western U.S. Wildfire Burned Forest Area With Warming

  AGU Advances · 2026-04-01

  articleOpen accessCorresponding

  Abstract Wildfires are projected to increase with warming in the western United States. Since vapor pressure deficit (VPD) is highly correlated with wildfire burned area historically, many studies have argued that large projected increases in VPD with warming imply large increases in burned area. Here, we argue that those projections are overestimated by as much as an order‐of‐magnitude. First, we show that both soil moisture and VPD are well correlated with historical burned forest area. Second, we demonstrate that projected changes in VPD with warming are much larger than those in soil moisture, leading to wildly divergent projections of burned forest area: with 3 K (4 K) of warming relative to pre‐industrial, the VPD‐based projection is about 16 (66) times the historical burned area, whereas the soil moisture‐based projection is only 2 (3) times the historical burned area. A similar divergence arises in more complex models that include VPD as only one of many explanatory variables. Third, we argue that the VPD‐based projections are incorrect. VPD is used as a measure of atmospheric evaporative demand, but recent advances have demonstrated that VPD and related quantities are actually poor measures of atmospheric evaporative demand and overstate projected drying with warming. We conclude that the rate at which wildfire burned forest area will increase with warming has been greatly overestimated by some studies.

  PublisherDOI

• Daily surface flux equilibrium (SFE) ET across CONUS

  Zenodo (CERN European Organization for Nuclear Research) · 2026-03-12

  datasetOpen access

  Daily, 4km estimates of surface flux equilibrium (SFE) ET across CONUS from "Triple collocation validates CONUS-wide evapotranspiration inferred from atmospheric conditions, McCormick et al. (In Minor Revision), Hydrology and Earth System Sciences.

  PublisherDOI

• Global ecosystem water limitation under warming driven by energy constraints and physiological CO2 effects

  2026-03-13

  articleOpen access

  Energy and water availability are essential controls on terrestrial ecosystem functions. Recent studies suggest widespread shifts from energy- to water-limited conditions under global warming. We demonstrate that incorporating a thermodynamically appropriate energy indicator fundamentally changes this projection. Surface energy availability for evapotranspiration is primarily determined by net radiation rather than downwelling shortwave radiation or air temperature, as supported by both theory and observations. Using this improved framework, we find no projected net increase in terrestrial ecosystem water limitation under greenhouse warming. Instead, projected bidirectional transitions between water- and energy-limited conditions exhibit comparable magnitudes, with a slight net reduction in the water-limited regime in 1.4% to 2.9% of global warm land areas. These findings are consistent with patterns reported in other ecohydrologically based studies and are supported by empirical evidence of reduced vegetation sensitivity to dry conditions under elevated CO2. Our study bridges ecological and physical theories to improve ecosystem water-energy limitation analysis and provide a clear mechanistic understanding of future ecosystem dynamics.

  PublisherDOI

• Supplementary material to "Triple collocation validates CONUS-wide evapotranspiration inferred from atmospheric conditions"

  2025-09-18

  articleOpen access
  PublisherDOI

• Radiative–Convective Equilibrium over an Idealized Land Surface with Fixed Soil Moisture

  Journal of Climate · 2025-09-18

  articleSenior author

  Abstract Radiative–convective equilibrium (RCE) is an idealized model of the atmosphere in which surface fluxes exactly balance radiative cooling. While recent work has shown RCE over land is a reasonable first-order model of continental climate, previous RCE studies have mainly focused on ocean surfaces. Unlike the ocean, the land surface has limited water and a low heat capacity. Here, we use theory and simulations to understand RCE over an idealized land surface with fixed soil moisture, a logical next step in the land climate model hierarchy. The fixed soil moisture case is also relevant to irrigated areas, groundwater-fed ecosystems, and broader debates about potential evapotranspiration (PET), aridity, and their changes in a warming world. We derive a parsimonious gray gas theory that reproduces major aspects of cloud-permitting simulations of RCE over an idealized land surface and permits analytic solutions for several special cases. Over fixed dry surfaces, the theory shows that hydrological sensitivity follows Clausius–Clapeyron scaling, considerably greater than the typical 2%–3% K −1 over oceans. Over fixed saturated surfaces, the theory reconciles divergent explanations for hydrological sensitivity based on surface and atmospheric energy budgets, with changes in near-surface relative humidity playing a key role. Finally, the theory shows that PET primarily scales with surface net radiation, rather than temperature or vapor pressure deficit, in agreement with recent empirical findings. The predicted PET scaling implies only modest changes in global mean aridity with warming, rather than the large increases implied by some prior studies. Biological plant responses to increasing carbon dioxide (CO 2 ) are not essential to this explanation. Significance Statement Will global warming make the world more arid? There has been a lot of debate on this question, with some arguing it will drastically increase aridity. Answering it requires understanding changes in atmospheric water demand: the evapotranspiration that would occur if the land surface was always kept saturated. We use basic physics to understand climate over land surfaces in which soils are kept saturated—and, more broadly, fixed at any level of saturation, from wet to dry. Our results support the view that global warming will not drastically increase aridity, on average. We also show that rainfall increases with warming at a faster rate over fixed dry land surfaces than it does on Earth (where land surfaces change from dry to wet and back again).

  PublisherDOI

Recent grants

• Explaining the Surprising Simplicity of Continental Evapotranspiration

  NSF · $335k · 2021–2025

Frequent coauthors

• Dara Entekhabi

  Massachusetts Institute of Technology

  102 shared

• Alexandra G. Konings

  Stanford University

  43 shared

• Luca Brocca

  Research Institute for Geo-Hydrological Protection

  42 shared

• Shirin Moradi

  39 shared

• Ruzbeh Akbar

  Jet Propulsion Laboratory

  38 shared

• Heye Bogena

  Forschungszentrum Jülich

  36 shared

• Carsten Montzka

  34 shared

• Randal D. Koster

  Goddard Space Flight Center

  34 shared

Labs

• Kaighin McCollPI