Manspeizer et al. (2026) Tracking a semi-arid Eastern Mediterranean ecotone through integration of terrestrial and atmospheric earth observation data (2000–2024)

Identification

• Journal: The Science of The Total Environment
• Year: 2026
• Date: 2026-03-09
• Authors: N. Manspeizer, Arnon Karnieli
• DOI: 10.1016/j.scitotenv.2026.181620

Research Groups

• The Albert Katz International School for Desert Studies, The Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Sede Boker Campus, Israel
• The Remote Sensing Laboratory, The Wyler Department of Dryland Agriculture, French Associates Institute for Agriculture and Biotechnology of Drylands, Blaustein Institutes for Desert Research, Sede Boker Campus, Ben Gurion University of the Negev, Israel

Short Summary

This study developed an Earth observation method to monitor semi-arid Eastern Mediterranean shrublands in relation to climate change and subtropical high migration, finding a 13.3% decrease in aridity and a doubling in the rate of atmospheric water vapor increase between 2014 and 2024. It proposes that ecological equilibrium occurs at plagioclimax following disturbance, challenging traditional succession theories.

Objective

• To develop an Earth observation method to monitor semi-arid Mediterranean shrublands in relation to climate change and subtropical high (SH) migration.
• To investigate if ecological equilibrium and a stable state occur at plagioclimax following critical levels of anthropogenic disturbance, rather than at climax.
• To hypothesize that local/regional semi-arid areas in the Eastern Mediterranean with access to large water bodies may become less arid despite global warming, questioning broader generalizations of the Clausius-Clapeyron relation.

Study Configuration

• Spatial Scale: Regional (Eastern Mediterranean, specifically Israel) to local (Carob-Mastic Park (CMP) vegetation alliance). Data resolutions ranged from 1 degree (MODIS) and 0.1 degree (AgERA5) for atmospheric data, to 30 meters (Landsat) for terrestrial data, with some terrestrial analyses resampled to 1 meter. Meteorological data from 35 sub-regional stations in Israel.
• Temporal Scale: 2000–2024 for atmospheric data (MODIS AWVR, AgERA5 VPD), 2010–2024 for meteorological data (Israel Meteorological Service), and 2014–2024 for terrestrial remote sensing data (Landsat 8/9).

Methodology and Data

• Models used:
  • Tasseled-Cap Transformation (TCT) to derive Brightness (BI), Greenness (GI), and Wetness (WI) indices.
  • Normalized Difference Climate-Line Index (NDCLI) (developed in this study) to quantify terrestrial non-stationarity.
  • Aridity Index (AI) calculated using the Hargreaves-Samani method.
  • Modified Shannon Entropy (MSE) for spatial entropy analysis.
  • Linear regression models for trend analysis and system disequilibrium.
  • Modified Clausius-Clapeyron relation for atmospheric dynamics.
• Data sources:
  • Satellite:
    • MODIS (Moderate Resolution Imaging Spectroradiometer) MOD08_M3 Level-3 for Atmospheric Water Vapor Reserve (AWVR).
    • Landsat 8 OLI-1 and Landsat 9 OLI-2 Level-2 for surface reflectance (SR).
    • VENμS (Vegetation and Environment Monitoring New Micro Satellite) and LiDAR imagery (for training sets).
    • Uncrewed Aerial Vehicle (UAV) imagery (for nested hierarchy classification).
  • Reanalysis:
    • AgERA5 for Vapor Pressure Deficit (VPD) at maximum temperature.
  • Observation/In-situ:
    • Israel Meteorological Service (IMS) climate archive data (daily precipitation, temperature from 35 stations).
  • Ancillary:
    • Survey of Israel (SOI) 20 cm orthophoto.
    • US Department of Energy (DOE) solar position calculator (SOLPOS) for extraterrestrial radiation.
    • Vegetation map of Israel.
    • Israel Geological Survey (IGS) digital maps (1:50000).
    • Israel Ministry of Agriculture and Volcanic Institute for Agricultural Research digital soil group map (1:20000).

Main Results

• Atmospheric Water Vapor Reserve (AWVR) in the study area increased by 0.43 g/cm² (22.5%) from 2000 to 2024, with the rate of increase nearly doubling between 2014 and 2024 (from 0.0096 g/cm²/yr to 0.018 g/cm²/yr).
• Between 2010 and 2024, average surface temperature increased by 0.75 °C (2.8%), precipitation increased by 66.5 mm (18.4%), and potential evapotranspiration (PET) increased by 33.5 mm/yr (2.3%).
• Aridity in the semi-arid zone decreased by 13.3% (from 0.2 to 0.5 on the Aridity Index scale) between 2010 and 2024.
• Vapor Pressure Deficit (VPD) in the sub-regional Eastern Mediterranean decreased by 0.56 hPa (2.8%) from 2000 to 2024, with a more pronounced summer decrease of 3.0 hPa (15.1%).
• The newly developed Normalized Difference Climate-Line Index (NDCLI) showed a 0.013° declination towards a wetter (less arid) scenario, quantifying ecotone non-stationarity relative to a thermodynamically dead state (TDS) baseline.
• A strong inverse annual relationship (R² = 0.47, p = 0.014) was found between NDCLI and AWVR, indicating an annual transfer of H₂O reserves between terrestrial and atmospheric systems.
• Spring greenness (TCT GI) showed an increasing trend (slope = 0.004) from 2014 to 2024, reflecting shrub encroachment or relative greening.
• Ecological equilibrium and a stable state were found to occur at plagioclimax following critical disturbance, rather than at climax.
• A modified Clausius-Clapeyron relation is proposed, where increased temperature and AWVR, coupled with decreased VPD and increased PET, lead to reduced aridity due to the availability of moisture from large water bodies.

Contributions

• Developed an innovative Earth observation method, the Normalized Difference Climate-Line Index (NDCLI), to quantify ecotone transition and monitor semi-arid shrublands.
• Introduced the concept of thermodynamically dead state (TDS) at equilibrium (plagioclimax) as a stable reference signal (TRS) for monitoring non-stationary thermodynamically live state (TLS) changes, challenging the rejection of equilibrium in disequilibrium ecology.
• Identified a modified Clausius-Clapeyron relation for the semi-arid Eastern Mediterranean, demonstrating that proximity to large water bodies can lead to decreased aridity despite global warming-induced temperature and atmospheric water vapor increases.
• Described a global/synoptic pathway of terrestrial-atmospheric H₂O transfer, linking Subtropical High (SH) migration and Cyprus Lows to moisture transport and ecotone formation.
• Quantified a decade-long intensification event in Atmospheric Water Vapor Reserve (2014-2024) and its impact on terrestrial greening.
• Demonstrated the potential of the NDCLI-AWVR model as an Earth observation early warning system for drought.

Funding

• Tuning for Deserts project, supported by the Israeli Council for Higher Education.

Citation

@article{Manspeizer2026Tracking,
  author = {Manspeizer, N. and Karnieli, Arnon},
  title = {Tracking a semi-arid Eastern Mediterranean ecotone through integration of terrestrial and atmospheric earth observation data (2000–2024)},
  journal = {The Science of The Total Environment},
  year = {2026},
  doi = {10.1016/j.scitotenv.2026.181620},
  url = {https://doi.org/10.1016/j.scitotenv.2026.181620}
}