Warming-induced hydrothermal anomaly over the Earth's three Poles amplifies concurrent extremes in 2022

The study addresses the rise in frequency and severity of concurrent heatwaves and heavy rainfall, particularly the cluster of record-breaking extremes from late spring to summer 2022 across both hemispheres. It examines whether common large-scale circulation patterns and specific forcings underpin these concurrent extremes. Anthropogenic warming increases mean temperatures and moisture, modifies circulation (weakened storm tracks, shifted/double jets, amplified quasi-stationary waves), and can synchronize temperature and precipitation extremes via both high- and low-latitude circulations (Walker, Hadley, monsoons). Beyond anthropogenic long-term forcing, interannual-to-seasonal predictors are needed. The paper hypothesizes that accelerated warming and cryospheric changes at Earth’s three Poles (Arctic, Antarctic, Tibetan Plateau) produce hydrothermal anomalies (albedo reduction, snow/ice melt, soil moisture anomalies) that, independently and synergistically, alter jets, Rossby waves, subtropical highs, and monsoon circulations to amplify concurrent extremes. The goal is to identify concurrent features of 2022 extremes, diagnose three-Poles hydrothermal anomalies and their independent/coupled effects, and clarify physical pathways to improve seasonal prediction and disaster preparedness.

The introduction synthesizes evidence that anthropogenic forcing raises both mean temperatures and variability influencing heavy precipitation. Prior work links extremes to nonuniform radiative forcing, enhanced atmospheric moisture, weakened and shifted jet streams, amplified quasi-stationary waves, and tropical circulations (Walker, Hadley, monsoons). Regional factors include Indo-Pacific and North Atlantic SST anomalies, ENSO teleconnections, and strong land–atmosphere feedbacks (soil moisture–temperature) behind 2022 East Asia extremes. Urban heat islands intensify heat and flood risk. High-diabatic heating regions (Europe, Tibetan Plateau) can generate eddy anomalies and downstream extreme events. Accelerated warming is observed in the Arctic (Arctic amplification), Tibetan Plateau (>2× global), and parts of Antarctica, with cryosphere changes (albedo, emissivity, insulation) affecting radiation, hydrology, sea level, and circulation. Arctic snow/ice loss is associated with slower, sometimes double, jets and amplified planetary waves, preconditioning blocking heatwaves and flood-prone regimes. Tibetan Plateau snow cover modulates East Asian precipitation via Asian summer monsoon and westerlies, influencing Eurasian heatwaves. Antarctic ice melt can affect the Northern Hemisphere through AMOC and inter-hemispheric monsoon adjustments. Despite this, studies explicitly connecting three-Poles ice/snow melt to concurrent heat and precipitation extremes have been lacking, motivating the present analysis.

Data and indices: Daily heatwaves are defined where daily temperature exceeds the local 90th percentile; precipitation extremes are days exceeding the local 90th percentile. A Temperature Co-occurring Index (TCI) quantifies co-occurrence between three high-temperature regions (100–125°E, 25–35°N; 10°W–30°E, 35–55°N; 130–100°W, 32–60°N) and three high-precipitation regions (50–80°E, 25–35°N; 105–120°E, 10–25°N; 110–135°E, 35–55°N). Outgoing longwave radiation (OLR) anomaly is defined as the difference between (100–125°E, 10–25°N) and (100–125°E, 25–35°N) to indicate ITCZ/Asian monsoon meridional position. Asian summer monsoon index follows Zhao et al. (2015). Circulation diagnostics include South Asia High (SAH), West Pacific Subtropical High (WPSH), North Africa Subtropical High (ASH), jet streams (EAPJS, NAJS), Mascarene High (MH), CGT, and ASM metrics. Analyses: Regressions of surface air temperature (T2m) and soil moisture onto TCI identify key hydrothermal regions. Correlation analyses (Pearson) relate regional heatwave and precipitation extremes to three-Poles variables: Arctic/Antarctic T2m, skin temperature (skt), albedo; Tibetan Plateau soil moisture, skt, albedo; and to circulation indices (SAH, WPSH, ASH, ASM, CGT, jets, ITCZ/OLR). Spatial anomalies for 2022 include T2m and soil moisture fields. Model experiments: Community Earth System Model (CESM v1.0.4) with interactive atmosphere, land, sea ice, and slab-ocean components is used for sensitivity tests. Forcings are applied April 1–June 30 over 40 model years for each: (1) Arctic: 50% reduction in snow depth and ice cover over 60°W–150°E, 60–85°N; (2) Antarctic: impose 2022 SST anomaly over 45°W–90°E, 85–60°S to emulate coastal ice/snow melt effects on SST; (3) Tibetan Plateau: 50% snow cover reduction over 70–100°E, 30–40°N; (4) Coupled three-Poles: combine all three forcings. Responses assessed for JJA (or MJ/AMJ as relevant) over key regions: Yangtze River (YZ), eastern Siberia (ESB), eastern and western Europe (EEU/WEU), western North America (WNA) for temperature; Pakistan (PK), South China (SC), Northeast Asia (NEA), Brazil (BR), and East/South Africa (ESAF) for precipitation. Water vapor flux and circulation composites contextualize teleconnections. Datasets: CPC global daily precipitation (0.5°), ERA5 circulation (0.25°), HadISST sea surface temperature and sea ice concentration (1.0° and 2.5°), and GLDAS soil moisture (0.25°).

- 2022 featured multiple record-breaking concurrent extremes: severe heatwaves in the Yangtze River basin, western and eastern Europe, western North America, and eastern Siberia; and extreme floods in Pakistan (JJA), South China (late May–June), Korea (Aug 7–11), and Northeast China (JJA), plus South Africa (Apr 11–12) and Brazil (May 29–Jun 1). - The Temperature Co-occurring Index (TCI) shows an amplified upward trend with a peak in 2022, indicating strong concurrence of temperature and precipitation extremes. Other notable high-TCI years include 2003, 2006, 2012, 2013, and 2018. - Hydrothermal anomalies in 2022: Significant late-spring to summer warming in key Arctic and Antarctic sectors (T2m anomalies exceeding ~4 °C in AMJ), and anomalously high soil moisture and snowmelt over the Tibetan Plateau in MJ, with records since 1979. Albedo reductions over the Arctic and Tibetan Plateau are pronounced in high-TCI years. - Spatially, warming in 2022 is stronger in the eastern hemispheric sectors of the Arctic and Antarctic, consistent with amplified ice/snow melt; TP snowmelt and soil wetness were exceptional. - Correlations (1979–2022) show significant positive relationships between regional heatwave frequencies (YZ, WEU, WNA, EEU, ESB) and precipitation extremes (PK, SC, NEA) and three-Poles hydrothermal factors (Arctic/Antarctic T2m and skt; TP soil moisture and skt), and negative correlations with albedo. Extremes across regions are interrelated, evidencing concurrent behavior. - Circulation anomalies in 2022: poleward-shifted and amplified Rossby waves; stronger/poleward westerly jets; poleward and zonally extended subtropical highs (WPSH, ASH); and weakened, southward-displaced Asian monsoon circulations (ASM/EASM). SAH intensity correlates with both heatwaves and precipitation extremes, modulating CGT and WPSH extension. - Water vapor transport links: MH divergence and cross-equatorial flows feed Arabian Sea, North Indian Ocean, South China Sea, then northward into East Asia, coupling with WPSH and midlatitude disturbances to realize floods in South China, Pakistan, NE Asia, and a Yangtze heatwave. - CESM sensitivity experiments: Independent Arctic, Antarctic, and Tibetan Plateau forcings, and their coupled application, all produce positive temperature anomalies over YZ, ESB, EEU, WEU, WNA and increase precipitation over PK, SC, and NEA. Mechanistically, forcings yield poleward subtropical jets, stronger CGT, weaker ASM, poleward MH and subtropical highs, and an equatorward ITCZ tendency under some forcings. Coupled three-Poles forcing amplifies these responses. A Western Europe temperature response shows regional uncertainty under coupled forcing, potentially tied to ASH behavior. - Cross-polar interactions: Arctic–TP and Antarctic–TP couplings via wave trains, interhemispheric temperature/pressure gradients, AMOC, and bipolar seesaw processes suggest feedbacks that can reinforce concurrent extremes. - Overall, three-Poles hydrothermal anomalies in 2022 were key modulators of concurrent tropical–extratropical extremes via circulation reorganization.

The study demonstrates that hydrothermal anomalies associated with accelerated warming and cryospheric changes at the Arctic, Antarctic, and Tibetan Plateau were instrumental in producing the 2022 concurrence of heatwaves and floods. By linking observed correlations, regression patterns, and model sensitivity results, the authors show that lower albedo and altered surface energy/hydrology at the three Poles weaken meridional temperature gradients and shift jets and subtropical highs poleward, while modulating the SAH, CGT, and ASM toward a weaker, southward-displaced state. These circulation changes increase heatwave risk in mid–high latitudes (e.g., Europe, North America, East Siberia, Yangtze River) and enhance moisture convergence and precipitation extremes over Asian monsoon regions (Pakistan, South China, Northeast Asia). The findings provide a physically consistent framework connecting cryospheric melt-induced hydrothermal anomalies to large-scale dynamics and concurrent extremes, offering pathways for seasonal predictability and risk reduction. The inter-polar and TP couplings further suggest compounded or synergistic effects that can escalate concurrent hazards across basins and hemispheres.

This work identifies a pronounced hydrothermal anomaly across Earth’s three Poles in 2022 and provides evidence that their independent and coupled effects amplified concurrent heatwaves and extreme precipitation through poleward jets, amplified Rossby waves, extended subtropical highs, and a weakened, southward-shifted Asian monsoon. A new co-occurrence index (TCI) captures the intensification of concurrent extremes, peaking in 2022. Observational analyses and CESM sensitivity experiments consistently indicate that snow/ice melt and associated surface energy–hydrology changes at the Arctic, Antarctic, and Tibetan Plateau were central to the 2022 extremes. The study underscores the utility of cryosphere-informed hydrothermal indicators and circulation diagnostics (SAH, WPSH, ASH, CGT, ASM, MH) for seasonal extreme-event outlooks. Future research should: (1) better isolate causality and quantify sensitivities across regions; (2) refine Antarctic forcing representations beyond SST proxies for coastal melt; (3) integrate ENSO, Indo-Pacific and Atlantic SST variability, and land-surface feedbacks into multi-driver attribution; (4) assess model uncertainties in subtropical high responses and European heatwave signals; and (5) develop operational prediction frameworks leveraging three-Poles hydrothermal metrics for multi-hazard early warnings.

- Antarctic cryospheric forcing is represented via imposed SST anomalies in the coastal Antarctic zone, not explicit ice/snow dynamics, which may limit fidelity of atmosphere–ice coupling. - Attribution relies on correlations, regressions, and sensitivity experiments rather than fully coupled initialized forecasts or formal causal inference; residual confounding by ENSO, IPO, Atlantic variability, and land feedbacks is possible. - Some regional responses (e.g., Western Europe temperature under coupled forcing) show uncertainty, potentially tied to subtropical high variability. - Indices and thresholds (90th percentile definitions for heat/precipitation, TCI formulation) may affect sensitivity and cross-region comparability. - Timescale translation from long-term anthropogenic forcing to seasonal prediction remains challenging; further validation across additional high-TCI years is needed.