Theory gaps in Earth Science

Representative open questions

Showing 30 of 66 — one per source paper, highest-quality first.

• G6-1.5K-MCB: Marine Cloud Brightening scenario design for the Geoengineering Model Intercomparison Project (GeoMIP) in CESM2.1, E3SMv2.0, and UKESM1.1 (2026) · doi

  Significant inter-model differences exist in temperature response patterns to SSP2-4.5 and midlatitude MCB across CESM2.1, E3SMv2.0, and UKESM1.1, but the underlying causes of these inter-model differences in MCB climate response sensitivity remain unexplained and require systematic investigation.

• The impact of aerosol-ice nuclei-cloud interactions on a typical spring dust-precipitation event in China (2026) · doi

  While the study demonstrates that considering both CCN and IN effects improves precipitation simulations by approximately 40% compared to CCN-alone schemes, the underlying mechanisms responsible for this improvement remain incompletely characterized. Investigation into the relative contributions and interactions between CCN and IN pathways across different meteorological and aerosol conditions is needed.

• Identifying regions that can constrain anthropogenic Hg emissions uncertainties through modelling (2026) · doi

  The multi-model intercomparison studies (e.g., Bieser et al., 2017 on vertical and interhemispheric mercury distribution) reveal discrepancies in modeled wet deposition of mercury, but the paper does not specify how to prioritize which deposition processes (oxidation of Hg(0) to Hg(II) by OH and O3, precipitation scavenging rates) require improved parameterization to better constrain regional emission estimates from wet deposition observations.

• Spatial perspective on environmental migration: Empirical insights from a spatiotemporal approach in the United States, 1970–2010 (2026) · doi

  Recovery migration behavior after environmental disasters (Curtis et al., 2015; Fussell et al., 2014) is documented in the literature, but the paper does not integrate a migration systems approach with spatial regression models to distinguish between permanent environmental migration and temporary displacement-recovery patterns across county-level spatial units.

• Validation of TROPOMI and WRF-Chem NO 2 across seasons using SWING+ and surface observations over Bucharest (2026) · doi

  The approximation in Equation A7 that neglects the integral ∫[AT(z) − AS(z)]δn(z)dz assumes the model performs well and that δn remains small above aircraft altitude. This assumption requires validation for urban pollution cases where NO2 vertical gradients are steep, particularly for the Bucharest case study.

• Revisiting the global budget of atmospheric glyoxal: updates on terrestrial and marine precursor emissions, chemistry, and impacts on atmospheric oxidation capacity (2026) · doi

  Atmospheric oxidation chemistry models require updated compact mechanisms for aromatic precursor oxidation pathways that produce glyoxal, with specific focus on benzene, toluene, and xylene degradation under varying NOx regimes to improve predictions of glyoxal concentrations in urban and industrial regions.

• Dynamics of island mass effect – Part 2: Phytoplankton physiological responses (2026) · doi

  The variability in η' decline across the three island mass effect (IME) zones (sharp decline in Samoa versus marginal decreases in Rapa Nui and Society Islands) despite detected upwelling signatures requires investigation of island-specific hydrodynamic and biogeochemical mechanisms controlling nutrient availability and phytoplankton physiological response patterns.

• Transport of volcanic aerosol from the Raikoke eruption in 2019 through the Northern Hemisphere (2026) · doi

  The mechanisms driving dilution of volcanic aerosol peaks in the ASMA through upwelling from lower potential temperature levels and dispersion with lateral mixing are identified qualitatively but lack quantitative analysis of the relative contributions of each process to the observed smoothing of enhanced BSR455 signals.

• Fracture Complexity and Seismicity Influenced by Mineral Heterogeneity and Fluid Viscosity in Hydraulic Fracturing of Simulated Crystalline Rock (2026) · doi

  The study demonstrates that grain-scale heterogeneity (G1 vs G2) influences both fracture complexity peak locations and the magnitude of viscosity-induced changes in Gutenberg–Richter b values, but does not quantify the relationship between specific mineral composition heterogeneity metrics (e.g., grain size distribution, mineralogical phase boundaries) and the threshold conditions for these seismic behavior transitions.

• Unraveling non-monotonic responses of the El Niño–Southern Oscillation to post-2100 global warming (2026) · doi

  The Wyrtki frequency (WF) and Bjerknes stability (BJ) indices are derived from multivariate linear regression of RO model parameters, but the paper does not assess how regression residuals (ξT and ξh) representing non-resolved nonlinear processes vary with global warming level or interact with the non-monotonic ENSO amplitude response mechanisms.

• Marine chemistry special issue: Aerosol chemistry and impacts on the ocean (2010) · doi

  Boyd et al. (2010) identify that dust-mediated phytoplankton blooms are probably rare due to slow iron dissolution timescales, but the specific dissolution kinetics and the quantitative relationship between iron supply modes (mechanisms, rates, timescales) and subsequent biological response thresholds remain incompletely characterized across different oceanographic regions and seasons.

• Environmental chemistry is the importance of chemistry to the environment (2014) · doi

  Eugenia jambolana essential oil demonstrated bioinsecticidal activity against Drosophila melanogaster and cytoprotective effects against mercury chloride, but the specific active constituents responsible for heavy metal chelation and their binding mechanisms with mercury remain unidentified, limiting reproducibility and field application.

• Turf Algae Monitoring on Artificial Reefs Using Underwater Photography and ImageJ (2026) · doi

  No quantitative sediment burial thresholds for turf algae suppression have been established; future studies must systematically vary sediment loads (beyond the Low <10 cm, Medium 10-29 cm, High ≥30 cm categories) and measure the resulting turf algae cover to derive specific sediment depth thresholds that trigger management actions.

• Atmospheric moisture transport anomalies and vegetation response in arid coastal ecosystems: insights from the 2017 coastal El Niño in northern Peru (2026) · doi

  The predominantly negative LAI-WVT relationships over the Amazon indicate that moisture transport interactions with background climatic conditions vary by ecosystem type, but the specific mechanisms by which enhanced cloud cover and reduced solar radiation mediate these relationships remain underspecified; detailed process studies isolating radiation effects from moisture supply effects in humid tropical ecosystems are needed.

• Earthquake Induced Landslide Identification to Support Landuse Planning in Rapid Growing Settlements Area of Imogiri and Dlingo Sub-District, Yogyakarta (2026) · doi

  The geological heterogeneity analysis contrasts the weak Semilir Formation (high-risk in Wukirsari) with the competent Wonosari Formation (lower vulnerability in Dlingo), but does not quantify how groundwater saturation and pore pressure changes from high-intensity rainfall (eastern sector) interact with formation-specific geotechnical properties to modulate earthquake-induced landslide susceptibility across formation boundaries.

• DEEP-SEAM: an explainable semi-supervised deep learning framework for mineral prospectivity mapping (2026) · doi

  The paper identifies that surface-indicative datasets (DEM, remote sensing, radiometric) outperform depth-indicative datasets (magnetic, gravity) in feature importance rankings for REE prospectivity; however, the mechanisms underlying this dominance and conditions under which subsurface geophysical data might become primary discriminators remain unexplored experimentally.

• Atmospheric Simulation Chambers in the ACTRIS Research Infrastructure (2026) · doi

  Chamber studies of biogenic secondary organic aerosol aging via OH radical reactions (Donahue et al., 2012) have been conducted, but the quantitative relationship between aging timescales in laboratory chambers (typically hours) and atmospheric aging pathways involving aerosol-phase reactions and heterogeneous uptake over days-to-weeks remains unconstrained for integration into regional and global chemical transport models.

• Coal seam porosity and water resources estimation based on big data analysis and deep learning models: A case study in the Surat Basin, Australia (2026) · doi

  The study uses a power-law distribution (n3d(l) = a·l^-b) fitted to 69 mapped faults with R² = 0.9031, but does not investigate whether this single distribution adequately characterizes fracture size distributions across different coal seams (A4 to D8) with varying lithologies or whether separate distributions are needed for conductive versus mixed fractures identified in image logs.

• Ionic Composition and Driving Factors of Salt Lake Brines in the Burabay Massif, Eastern Kazakhstan (2026) · doi

  Lakes 1, 2, and 7 deviate from the pronounced linear positive Na⁺–Cl⁻ correlation observed in high-mineralization lakes (5, 6, 12, 13, 14), suggesting differential affinity to halogenite equilibrium. The specific mechanisms causing these deviations in lower-mineralization systems and their implications for predicting water quality changes under varying hydrological and climate conditions require targeted investigation.

• Mechanisms of Intermediate-Depth Seismicity in Eastern Java: Insights from the 2021 Malang Intraslab Earthquake Sequence and Earthquake-Hazard Assessment (2026) · doi

  The paper documents dynamic interactions between slab pull, mantle flow, and dehydration processes influencing both intermediate-depth ruptures and shallow megathrust rupture recurrence, but provides no quantitative model or time-series analysis constraining how stress transfer from the 70-120 km dehydration zone propagates to the shallow plate-boundary interface. Coupled mechanical models that link intraslab stress redistribution to megathrust earthquake triggering specifically in the Java subduction zone are absent.

• Riparian ecosystem condition and impaired floodplain assessment in the Congaree river watershed, South Carolina (2026) · doi

  The RCA–FIS assessment addresses changing climate and land-use pressures affecting floodplain health, but does not incorporate temporal projections of how riparian condition indicators will respond to specific climate change scenarios (temperature increase, precipitation variability) or projected land-use transitions in the Congaree watershed under different future pathways.

• Selective extraction of metals from polymetallic nodules of Central Indian Ocean Basin through chemical partitioning (2026) · doi

  The adsorption behavior of minor elements (Cu, Ni, Co, Zn) onto iron hydroxide during chemical partitioning is described phenomenologically, but the underlying adsorption mechanisms, equilibrium constants, and pH-dependent partitioning kinetics for each element remain uncharacterized. Quantitative investigation of these adsorption isotherms and thermodynamic parameters would improve predictive accuracy for industrial-scale extraction.

• The chemistry of climate change (2012) · doi

  Contrails are noted to have a warming effect where water vapor forcing outweighs albedo cooling, but the paper provides no mechanistic model for how contrail properties (optical depth, lifetime, altitude, ice crystal size) vary with atmospheric conditions or how this translates to climate forcing at different latitudes and times of day.

• Collapse of the Atlantic meridional overturning circulation would lead to substantial oceanic carbon release and additional global warming (2026) · doi

  While monsoon rainfall impacts of AMOC collapse are addressed in a multi-model comparison (citation 21), the mechanisms linking Atlantic Meridional Overturning Circulation weakening to oceanic carbon release and subsequent regional precipitation changes remain incompletely characterized. Coupled ocean-atmosphere modeling studies should explicitly isolate the carbon cycle feedbacks that mediate AMOC-monsoon teleconnections.

• Climate change-induced agricultural disasters and policy-based agricultural insurance: empirical findings from China (2026) · doi

  The modest adjustment speed coefficient (−0.263) suggests gradual market correction reflecting institutional frictions, but the paper does not specify which institutional barriers (e.g., information asymmetries, premium subsidy delays, claim settlement lags) drive this slow adjustment or propose targeted policy reforms to accelerate the market's response to changing disaster patterns.

• Human-induced intensification of sea surface temperature regime shifts threatens global Large Marine Ecosystems (2026) · doi

  While the paper documents regime shifts in fish recruitment and growth rates across the Northeast Atlantic, Humboldt Current, and Northwestern Pacific, there is no explicit analysis of whether the mechanistic drivers causing SST regime shifts (e.g., Pacific Decadal Oscillation modulation, Atlantic Multidecadal Oscillation intensification) operate identically across different LMEs or whether regional-specific ocean-atmosphere coupling processes require distinct modeling frameworks.

• Reassessing Recent Tectonic Activity in Western Svalbard: Fault Kinematics and Crustal Deformation Patterns (2026) · doi

  Sediment flux records from glacial fjords (Isfjorden) and Cenozoic sedimentation patterns along the southwestern Barents Sea shelf provide proxy evidence for crustal uplift and exhumation, but quantitative forward modeling linking fjord sediment accumulation rates to geodetically-measured present-day vertical crustal motion rates remains underdeveloped.

• Supplementary material to "Advancing Isotope-Enabled Model for Comprehensive Understanding of Atmospheric Sulfur Isotope Effects: Revealing the Overlooked Isotopic Fractionation During Combustion and Gas Desulfurization" (2026) · doi

  The model's treatment of transition-metal ion-catalyzed SO₂ oxidation pathways (identified by Li et al. 2020 as a major mechanism during haze episodes) requires explicit parameterization of isotopic fractionation factors for different oxidation catalysts (Fe³⁺, Mn²⁺, etc.) under varying pH and aerosol water composition conditions not currently specified in the thermodynamic equilibrium framework.

• SEM-EDX IDENTIFICATION AND CHARACTERIZATION OF AIRBORNE MICROSPHERES: POTENTIAL EFFECTS ON HUMAN HEALTH (2023) · doi

  Cell viability effects of airborne ultrafine particles are studied using electron microscopic analysis, but the specific contribution of individual microsphere chemical constituents (identified via EDX) to cytotoxicity and inflammatory responses remains unknown. Dose-response relationships between specific elemental compositions of microspheres and cellular toxicity need establishment.

• Assessing Environmental Pollution: Quality Control Using CRITIC-WASPAS Methods under Intuitionistic Fuzzy Z-Numbers (2026) · doi

  The choice of specific intuitionistic fuzzy Z-number scale parameters (e.g., the membership and non-membership interval ranges used: (0.0, 0.9) and related bounds) lacks justification and calibration with actual environmental pollution measurement standards or thresholds for real pollutants.