Climate Sensitivity Research Articles

Continental lowlands face rising crop vulnerability: structural change in regional climate sensitivity of crop yields, Hungary (Central and Eastern Europe), 1921–2010

Central and Eastern Europe (CEE) is a pillar of global wheat and maize production. However, certain areas within the CEE region have become climate change hotspots, experiencing intensifying water deficits and drought pressure, rising mean and maximum temperatures. This study focuses on the long-term statistical relationships between climatic factors and rain-fed wheat and maize yields for different landscape types in Hungary over 30-year time windows between 1921 and 2010. The relationship between the variances of the detrended climatic parameters and crop yields was tested employing both simple and multifactorial linear models according to landscape types and periods. The sensitivity of wheat yields to spring–summer mean temperature shifted dynamically from the western part of the country to east (from cooler and wetter hilly landscapes to plains) between the periods 1921–1950 and 1981–2010. The cooling observed in summer temperature between the periods 1921–1950 and 1951–1980 supported an increase in wheat yields by an estimated 0.11–0.43 t ha−1 year−1, while the 0.9–1.2 °C warming of May–July temperature may have cut wheat yields by an estimated 0.44–0.56 t ha−1 year−1 in various regions over 1981–2010. That being said, the regional sensitivity of wheat yields to May–July mean temperature did not display substantial differences between the periods 1921–1950 and 1981–2010. Besides negative effects, climate change had a positive impact on wheat yields, since increasing January–March mean temperatures mitigated the negative impact of warming summer temperatures on wheat yields by an estimated 16–34% over 1981–2010. In this 30-year period, increasing mean temperature together with decreasing precipitation explained 46–75% of the variances in maize yields reducing annual maize harvests by an estimated 11.1–12.4% year−1.

Prediction of volatility and seasonality vegetation by using the GARCH and Holt-Winters models.

Seasonality and volatility of vegetation in the ecosystem are associated with climatic sensitivity, which can have severe consequences for the environment as well as on the social and economic well-being of the nation. Monitoring and forecasting vegetation growth patterns in ecosystems significantly rely on remotely sensed vegetation indices, such as Normalized Difference Vegetation Index (NDVI). A novel integration of the Generalized Autoregressive Conditional Heteroskedasticity (GARCH) and the Holt-Winters (H-W) models was used to simulate the seasonality and volatility of the three different agro-climatic zones in Jharkhand, India: the central north-eastern, eastern, and south-eastern agro-climatic zones. MODIS Terra Vegetation Indices NDVI data MOD13Q1, from 2001 to 2021, was used to create NDVI time series volatility and seasonality modeled by the GARCH and the H-W models, respectively. GARCH-based Exponential GARCH (EGARCH) [1,1] and Standard GARCH (SGARCH) [1,1] models were used to check the volatility of vegetation growth in three different agro-climatic zones of Jharkhand. The SGARCH [1,1] and EGARCH [1,1] models for the western agro-climatic zone experienced the best indicator as it has maximum likelihood and minimal Schwarz-Bayesian criterion and Akaike information criterion. The seasonality results showed that the additive H-W model showed better results in the eastern agro-climatic zone with the optimized values of MAE (16.49), MAPE (0.49), NSE (0.86), RMSE (0.49), and R2 (0.82) followed by the south-eastern and central north-eastern agro-climatic zones. By utilizing the H-W and GARCH models, the finding demonstrates that vegetation orientation and monitoring seasonality can be predicted using NDVI.

Do bankers on board fulfill their role? Corporate social responsibility, environmental concerns and firm leverage

AbstractUsing a dataset of listed Indian manufacturing firms for 2010–2020, the study examines their financial response to climate risks in the presence of banker‐directors. The results show that climate sensitivity and vulnerability exert a negative impact on firm leverage and cost whereas climate adaptation has relatively limited impact. These effects broadly resonate across firm ownership, although it differ across firm‐bank equity interlocks. The overall impact of these developments is manifest in a decline in investment. The findings suggest that policymakers need to be more responsive to firm‐bank interactions, as these can impact firm behavior and have real economic consequences.

A high-resolution calving front data product for marine-terminating glaciers in Svalbard

Abstract. The mass loss of glaciers outside the polar ice sheets has been accelerating during the past several decades and has been contributing to global sea-level rise. However, many of the mechanisms of this mass loss process are not well understood, especially the calving dynamics of marine-terminating glaciers, in part due to a lack of high-resolution calving front observations. Svalbard is an ideal site to study the climate sensitivity of glaciers as it is a region that has been undergoing amplified climate variability in both space and time compared to the global mean. Here we present a new high-resolution calving front dataset of 149 marine-terminating glaciers in Svalbard, comprising 124 919 glacier calving front positions during the period 1985–2023 (https://doi.org/10.5281/zenodo.10407266, Li et al., 2023). This dataset was generated using a novel automated deep-learning framework and multiple optical and SAR satellite images from Landsat, Terra-ASTER, Sentinel-2, and Sentinel-1 satellite missions. The overall calving front mapping uncertainty across Svalbard is 31 m. The newly derived calving front dataset agrees well with recent decadal calving front observations between 2000 and 2020 (Kochtitzky and Copland, 2022) and an annual calving front dataset between 2008 and 2022 (Moholdt et al., 2022). The calving fronts between our product and the latter deviate by 32 ± 65 m on average. The R2 of the glacier calving front change rates between these two products is 0.98, indicating an excellent match. Using this new calving front dataset, we identified widespread calving front retreats during the past four decades, across most regions in Svalbard except for a handful of glaciers draining the ice caps Vestfonna and Austfonna on Nordaustlandet. In addition, we identified complex patterns of glacier surging events overlaid with seasonal calving cycles. These data and findings provide insights into understanding glacier calving mechanisms and drivers. This new dataset can help improve estimates of glacier frontal ablation as a component of the integrated mass balance of marine-terminating glaciers.

Evaluation of Stratocumulus Evolution Under Contrasting Temperature Advections in CESM2 Through a Lagrangian Framework

AbstractThis study leveraged a Lagrangian framework to examine the evolution of stratocumulus clouds under cold and warm advections (CADV and WADV) in the Community Earth System Model 2 (CESM2) against observations. We found that CESM2 simulates a too rapid decline in low‐cloud fraction (LCF) and cloud liquid water path (CLWP) under CADV conditions, while it better aligns closely with observed LCF under WADV conditions but overestimates the increase in CLWP. Employing an explainable machine learning approach, we found that too rapid decreases in LCF and CLWP under CADV conditions are related to overestimated drying effects induced by sea surface temperature, whereas the substantial increase in CLWP under WADV conditions is associated with the overestimated moistening effects due to free‐tropospheric moisture and surface winds. Our findings suggest that overestimated drying effects of sea surface temperature on cloud properties might be one of crucial causes for the high equilibrium climate sensitivity in CESM2.

Spatiotemporal patterns and driving factors of gross primary productivity over the Mongolian Plateau steppe in the past 20 years

The Eurasian steppe is the largest temperate grassland in the world. The grassland of the Mongolian Plateau (MP) represents an important part of the Eurasian steppe with high climatic sensitivity. Gross primary productivity (GPP) is a key indicator of the grassland's production, status and dynamic on the MP. In this study, we calibrated and evaluated the grassland-specific light use efficiency model (GRASS-LUE) against the observed GPP collected from nine eddy covariance flux sites on the MP, and compared the performance with other four GPP products (MOD17, VPM, GLASS and GOSIF). GRASS-LUE with higher R2 (0.91) and lower root mean square error (RMSE = 0.99 gC m−2 day−1) showed a better performance compared to the four GPP products in terms of model accuracy and dynamic consistency, especially in typical and desert steppe. The parameters of the GRASS-LUE are more suitable for water-limited grassland could be the reason for its outstanding performance in typical and desert steppe. Mean grassland GPP derived from GRASS-LUE was higher in the east and lower in the west of the MP. Grassland GPP was on average 205 gC m−2 over the MP between 2001 and 2020 with mean annual total GPP of 322 TgC yr−1. 30 % of the MP steppe showed a significant GPP increase. Growing season precipitation is the main factor affecting GPP of the MP steppe across regions. Anthropogenic factors (livestock density and population density) had greater effect on GPP than growing season temperature in pastoral counties in IM that take grazing as one of main industries. These findings can inform the status and trend of the productivity of MP steppe and help government and scientific research institutions to understand the drivers for spatial pattern of grassland GPP on the MP.

State-dependent impact of major volcanic eruptions observed in ice-core records of the last glacial period

Abstract. Recently, a record of large, mostly unknown volcanic eruptions occurring during the younger half of the last glacial period (12–60 ka) has been compiled from ice-core records. In both Greenland and Antarctica these eruptions led to significant deposition of sulfate aerosols, which were likely transported in the stratosphere, thereby inducing a climate response. Here we report the first attempt to identify the climatic impact of volcanic eruptions in the last glacial period from ice cores. Average negative anomalies in high-resolution Greenland and Antarctic oxygen isotope records suggest a multi-annual volcanic cooling. Due to internal climate variability, glaciological noise, and uncertainties in the eruption age, the high-frequency noise level often exceeds the cooling induced by individual eruptions. Thus, cooling estimates for individual eruptions cannot be determined reliably. The average isotopic anomaly at the time of deposition also remains uncertain, since the signal degrades over time as a result of layer thinning and diffusion, which act to lower the resolution of both the oxygen isotope and sulfur records. Regardless of these quantitative uncertainties, there is a clear relationship of the magnitude of isotopic anomaly and sulfur deposition. Further, the isotopic signal during the cold stadial periods is larger in Greenland and smaller in Antarctica than during the milder interstadial periods for eruptions of equal sulfur deposition magnitude. In contrast, the largest reductions in snow accumulation associated with the eruptions occur during the interstadial periods. This may be the result of a state-dependent climate sensitivity, but we cannot rule out the possibility that changes in the sensitivity of the isotope thermometer or in the radiative forcing of eruptions of a given sulfur ejection may play a role as well.

Assessing changes in global fire regimes

BackgroundThe global human footprint has fundamentally altered wildfire regimes, creating serious consequences for human health, biodiversity, and climate. However, it remains difficult to project how long-term interactions among land use, management, and climate change will affect fire behavior, representing a key knowledge gap for sustainable management. We used expert assessment to combine opinions about past and future fire regimes from 99 wildfire researchers. We asked for quantitative and qualitative assessments of the frequency, type, and implications of fire regime change from the beginning of the Holocene through the year 2300.ResultsRespondents indicated some direct human influence on wildfire since at least ~ 12,000 years BP, though natural climate variability remained the dominant driver of fire regime change until around 5,000 years BP, for most study regions. Responses suggested a ten-fold increase in the frequency of fire regime change during the last 250 years compared with the rest of the Holocene, corresponding first with the intensification and extensification of land use and later with anthropogenic climate change. Looking to the future, fire regimes were predicted to intensify, with increases in frequency, severity, and size in all biomes except grassland ecosystems. Fire regimes showed different climate sensitivities across biomes, but the likelihood of fire regime change increased with higher warming scenarios for all biomes. Biodiversity, carbon storage, and other ecosystem services were predicted to decrease for most biomes under higher emission scenarios. We present recommendations for adaptation and mitigation under emerging fire regimes, while recognizing that management options are constrained under higher emission scenarios.ConclusionThe influence of humans on wildfire regimes has increased over the last two centuries. The perspective gained from past fires should be considered in land and fire management strategies, but novel fire behavior is likely given the unprecedented human disruption of plant communities, climate, and other factors. Future fire regimes are likely to degrade key ecosystem services, unless climate change is aggressively mitigated. Expert assessment complements empirical data and modeling, providing a broader perspective of fire science to inform decision making and future research priorities.

One hundred and six years of change in a Sonoran Desert plant community: Impact of climate anomalies and trends in species sensitivities.

A major restriction in predicting plant community response to future climate change is a lack of long-term data needed to properly assess species and community response to climate and identify a baseline to detect climate anomalies. Here, we use a 106-year dataset on a Sonoran Desert plant community to test the role of extreme temperature and precipitation anomalies on community dynamics at the decadal scale and over time. Additionally, we tested the climate sensitivity of 39 desert plant species and whether sensitivity was associated with growth form, longevity, geographic range, or local dominance. We found that desert plant communities had shifted directionally over the 106 years, but the climate had little influence on this directional change primarily due to nonlinear shifts in precipitation anomalies. Decadal-scale climate had the largest impact on species richness, species relative density, and total plant cover, explaining up to 26%, 45%, and 55% of the variance in each, respectively. Drought and the interaction between the frequency of freeze events and above-average summer precipitation were among the most influential climate factors. Increased drought frequency and wetter periods with frequent freeze events led to larger reductions in total plant cover, species richness, and the relative densities of dominant subshrubs Ambrosia deltoidea and Encelia farinosa. More than 80% of the tested species were sensitive to climate, but sensitivity was not associated with a species' local dominance, longevity, geographic range, or growth form. Some species appear to exhibit demographic buffering, where when they have a higher sensitivity to drought, they also tend to have a higher sensitivity to favorable (i.e., wetter and hotter) conditions. Overall, our results suggest that, while decadal-scale climate variation substantially impacts these desert plant communities, directional change in temperature over the last century has had little impact due to the relative importance of precipitation and drought. With projections of increased drought in this region, we may see reductions in total vegetation cover and species richness due to the loss of species, possibly through a breakdown in their ability to demographically buffer climatic variation, potentially changing community dynamics through a change in facilitative and competitive processes.

Drivers of compositional turnover in narrow‐ranged and widespread dragonflies and damselflies in Africa

Abstract We aim to explore what processes dominate community assembly of dragonflies (Odonata: Anisoptera) and damselflies (Odonata: Zygoptera) by differentiating the environmental and geographical drivers behind compositional turnover of narrow‐ranged versus widespread species. In this way, we further aim to describe patterns of species incidence and compositional turnover to expand upon the body of knowledge related to understanding biodiversity patterns and processes. We explored species turnover of dragonflies and damselflies separately, using zeta diversity to measure compositional turnover among multiple assemblages. Narrow‐ranged and widespread species within each suborder showed similar drivers. Specifically, both narrow‐ranged and widespread dragonflies show rapid turnover with small shifts in annual mean temperature, temperature seasonality and annual precipitation, whereas for damselflies, the major driver for turnover is distance between sites followed by climatic variables. Our results therefore show that odonate turnover is largely driven by climate, although the limited dispersal capabilities of damselflies also influences community assembly. Climate change could cause major changes in composition of odonates, presenting a challenge for conservation planning in Africa as species assemblages that were previously conserved may no longer be protected if their ranges shift outside protected areas. For damselflies, adaptation is a major concern, and with their limited dispersal capabilities and climate sensitivity, they may not be able to migrate effectively in response to changing climate conditions. The underlying assembly processes do not differ considerably for narrow‐ranged and widespread species within each suborder, suggesting that conservation planning tailored to each suborder may be sufficient in Africa.

Cloud properties and their projected changes in CMIP models with low to high climate sensitivity

Abstract. Since the release of the first Coupled Model Intercomparison Project version 6 (CMIP6) simulations, one of the most discussed topics is the higher effective climate sensitivity (ECS) of some of the models, resulting in an increased range of ECS values in CMIP6 compared to previous CMIP phases. An important contribution to ECS is the cloud climate feedback. Although climate models have continuously been developed and improved over the last few decades, a realistic representation of clouds remains challenging. Clouds contribute to the large uncertainties in modeled ECS, as projected changes in cloud properties and cloud feedbacks also depend on the simulated present-day fields. In this study, we investigate the representation of both cloud physical and radiative properties from a total of 51 CMIP5 and CMIP6 models. ECS is used as a simple metric to group the models, as the sensitivity of the physical cloud properties to warming is closely related to cloud feedbacks, which in turn are known to have a large contribution to ECS. Projected changes in the cloud properties in future scenario simulations are analyzed by the ECS group. In order to help with interpreting the projected changes, model results from historical simulations are also analyzed. The results show that differences in the net cloud radiative effect as a reaction to warming among the three model groups are driven by changes in a range of cloud regimes rather than individual regions. In polar regions, high-ECS models show a weaker increase in the net cooling effect of clouds, due to warming, than the low-ECS models. At the same time, high-ECS models show a decrease in the net cooling effect of clouds over the tropical ocean and the subtropical stratocumulus regions, whereas low-ECS models show either little change or even an increase in the cooling effect. Over the Southern Ocean, the low-ECS models show a higher sensitivity of the net cloud radiative effect to warming than the high-ECS models.

Increasing Winter Temperatures Stimulate Scots Pine Growth in the North German Lowlands Despite Stationary Sensitivity to Summer Drought

More than half of the forest area of the North German Lowlands is stocked with Scots pine-dominated forests, mostly plantations. Climate change suggests a declining suitability of Europe’s temperate zone for conifer plantations, but only a few studies have examined the long-term growth trends of Scots pine in relation to environmental and site factors in this region. We studied the radial growth patterns of Scots pine over the last 60 years at ten sites along a precipitation gradient (830–530 mm mean annual precipitation) from an oceanic to a subcontinental climate, analyzing the spatial and temporal variability of the climate sensitivity of growth to identify the main climatic factors influencing pine growth across this gradient, which covers a large part of the species’ tolerated precipitation range. Annual radial increment was sensitive to late-winter temperatures (February, March) and summer drought and heat (June–August), with sensitivity increasing from the oceanic to the drier continental sites. Warmer late-winter periods apparently have stimulated growth during the last decades, while the sensitivity to summer-drought has remained fairly stable. Until recently, the negative impact of warming summers on growth has been compensated by the positive effect of late-winter warming, resulting in stable (or increasing) growth trends. However, our comparison of the climate sensitivity across sites suggests that the drought effect compensation through winter warming will in future be limited by increasing drought exposure. Thus, future productivity declines are likely in the northern German lowlands despite warming winters, discouraging large-scale pine plantations in the face of climate warming.

KNMI'23 Climate Scenarios for the Netherlands: Storyline Scenarios of Regional Climate Change

AbstractThis paper presents the methodology for the construction of the KNMI'23 national climate scenarios for the Netherlands. We have developed six scenarios, that cover a substantial part of the uncertainty in CMIP6 projections of future climate change in the region. Different sources of uncertainty are disentangled as much as possible, partly by means of a storyline approach. Uncertainty in future emissions is covered by making scenarios conditional on different SSP scenarios (SSP1‐2.6, SSP2‐4.5, and SSP5‐8.5). For each SSP scenario and time horizon (2050, 2100, 2150), we determine a global warming level based on the median of the constrained estimates of climate sensitivity from IPCC AR6. The remaining climate model uncertainty of the regional climate response at these warming levels is covered by two storylines, which are designed with a focus on the annual and seasonal mean precipitation response (a dry‐trending and wet‐trending variant for each SSP). This choice was motivated by the importance of future water management to society. For users with specific interests we provide means how to account for the impact of the uncertainty in climate sensitivity. Since CMIP6 GCM data do not provide the required spatial detail for impact modeling, we reconstruct the CMIP6 responses by resampling internal variability in a GCM‐RCM initial‐condition ensemble. The resulting climate scenarios form a detailed storyline of plausible future climates in the Netherlands. The data can be used for impact calculations and assessments by stakeholders, and will be used to inform policy making in different sectors of Dutch society.

Understanding the Diversity of CMIP6 Models in the Projection of Precipitation Over Tibetan Plateau

AbstractA reliable projection of precipitation over the Tibetan Plateau (TP) is crucial for climate adaptation activities in this climate‐sensitive region, but existing studies show a large spread in magnitude. Based on Coupled Model Intercomparison Project Phase 6 models, we investigate the TP summer precipitation projection and understand the sources of uncertainty. The results show that the TP exhibits a profound wetting trend throughout the 21st century, with precipitation increasing by 0.64 ± 0.06 mm day−1 during 2050–2099 under the SSP5–8.5 scenario. The moisture budget analysis indicates that the thermodynamical response to global warming determines the precipitation increase. However, both the thermodynamical and dynamical components contribute to the uncertainty of precipitation projection. The inter‐model spread of the thermodynamic term arises from divergent global mean warming, which is closely related to model climate sensitivity. The uncertainty of the dynamic component is driven by model‐dependent circulation changes induced by different equatorial Pacific warming rates.

Atmosphere and ocean energy transport in extreme warming scenarios

Extreme scenarios of global warming out to 2300 from the SSP5-8.5 extension scenario are analyzed in three state-of-the-art climate models, including two models with climate sensitivity greater than 4.5°C. The result is some of the largest warming amounts ever seen in simulations run over the historical record and into the future. The simulations exhibit between 9.3 and 17.5°C global mean temperature change between pre-Industrial and the end of the 23rd century. The extremely large changes in global temperature allow exploration of fundamental questions in climate dynamics, such as the determination of moisture and energy transports, and their relation to global atmosphere-ocean circulation. Three models performed simulations of SSP5-8.5 to 2300: MRI-ESM2-0, IPSL-CM6A-LR, and CanESM5. We analyze these simulations to improve understanding of climate dynamics, rather than as plausible futures. In the model with the most warming, CanESM5, the moisture content of the planet more than doubles, and the hydrologic cycle increases in intensity. In CanESM5 and IPSL-CM6A-LR nearly all sea ice is eliminated in both summer and winter in both hemispheres. In all three models, the Hadley circulation weakens, the tropopause height rises, and storm tracks shift poleward, to varying degrees. We analyze the moist static energy transports in the simulations using a diffusive framework. The dry static energy flux decreases to compensate for the increased moisture transport; however the compensation is imperfect. The total atmospheric transport increases but not as quickly as expected with a constant diffusivity. The decrease in eddy intensity plays an important role in determining the energy transports, as do the pattern of cloud feedbacks and the strength of ocean circulations.

Different patterns of inter-annual variability in mean vessel area and tree-ring widths of beech from provenance trials in Slovenia and Hungary

Key messageStudied beech provenances showed different patterns of inter-annual variability in mean vessel area and ring widths, indicating influence of intraspecific variability and diverse environment on hydraulic conductivity and carbon storage potential.International provenance trials of ecologically and economically important tree species are crucial to deciphering the influence of environmental factors and intraspecific variability on tree growth and performance under climate change to guide assisted gene flow and assisted migration of tree provenances and species. In this context, we compared inter-annual trends in tree-ring widths (carbon sequestration potential) and vessel characteristics (conductivity optimisation) of four beech provenances in two international provenance trials, one in Slovenia (Kamenski hrib, a core beech growing site) and one in Hungary (Bucsuta, a marginal beech site) in 2009–2019. We found different patterns of inter-annual variability in mean vessel area and tree-ring widths among provenances and sites, pointing to diverse genetic background and environmental influence on these two wood-anatomical traits. The average values of the vessel area varied less between provenances at Kamenski hrib than at Bucsuta. Weather conditions differently affected tree-ring width and mean vessel area. Furthermore, the length of the period of response of vessel area to the analysed weather conditions differed in summer and winter periods. The differences in the mean vessel area within the tree ring were more pronounced in the weather-wise extreme years, regardless of the provenance. Consistent with previous studies, we confirmed that site conditions affect the climate sensitivity of trees, which is more pronounced at marginal sites or in extreme years. The findings on how different environmental conditions affect the radial growth of young beech trees of different origin are very important for future forest management.

Global warming alters Himalayan alpine shrub growth dynamics and climate sensitivity

Global climate change is having significant effects on plant growth patterns and mountain plants can be particularly vulnerable to accelerated warming. Rising temperatures are releasing plants from cold limitation, such as at high elevations and latitudes, but can also induce drought limitation, as documented for trees from lower elevations and latitudes. Here we test these predictions using a unique natural experiment with Himalayan alpine shrub Rhododendron anthopogon and its growth responses to changing climate over a large portion of its latitudinal and elevational ranges, including steep precipitation and temperature gradients. We determined growth dynamics during the last three decades, representing period of accelerated warming, using annual radial growth increments for nine populations growing on both wet and warm southern localities and drier and cold northern localities in the Himalayas along elevation gradients encompassing the lower and upper species range limits. A significant growth increase over past decades was observed after controlling for confounding effect of shrub age and microsites. However, the magnitude of increase varied among populations. Particularly, populations situated in the lower elevation of the northernmost (cold and dry) locality exhibited most substantial growth enhancement. The relationship between growth variability and climate varied among populations, with the populations from the coldest location displaying the strongest responsiveness to increasing minimum temperatures during July. Minimum temperatures of April and August were the most important factor limiting the growth across most populations. Potential warming-induced drought limitation had no significant impact on growth variation in any part of the species geographic range. Overall, our findings indicate that plant growth is continuously increasing in recent decades and growth-climate relationships are not consistent across populations, with populations from the coldest and wettest localities showing stronger responses. The observed patterns suggest that dwarf-shrubs benefit from ongoing warming, leading to increased shrubification of high elevation alpine ecosystems.

The palaeoclimatic potential of recent oak tree-ring width chronologies from Southwest Ukraine

Better insights into spatio-temporal climate signals are needed to understand more clearly the applicability to palaeoclimatic analysis and dendrochronological dating of the long tree-ring oak chronologies currently being compiled in Eastern Europe. This study investigates the climate sensitivity of two recent oak tree-ring width (TRW) chronologies from Transcarpathian and Ciscarpathian Ukraine and their coherence with 35 oak chronologies from Ukraine, Poland, Slovakia, Romania, and Hungary. The new Transcarpathian chronology consists of 247 TRW series of living trees from 13 sites covering the period 1836–2020, while the new Ciscarpathian chronology consists of 215 TRW series from 13 sites and spans the period 1775–2020. Despite the strong similarity between these two chronologies, their responses to climate differ significantly. Growing-season precipitation and particularly drought (three-month SPEI index) were found to be the primary drivers of oak growth on the border between the Carpathians and the northeastern Pannonian Basin. Spatial correlations of the Transcarpathian chronology show particularly high explained variability in the April-August SPEI index, roughly between 18.5–28.5°E and 45–52°N. In the Ciscarpathian, June precipitation primarily influenced oak radial growth but the spatial correlation was quite low. While the Transcarpathian TRW chronology was strongly correlated with eastern Slovakian and northwestern Romanian chronologies, the Ciscarpathian chronology revealed very low correlations with surrounding chronologies. This study indicates the great dendroarchaeological and palaeoclimatic potential of the Transcarpathian chronology and points to the need to analyse additional living trees from the Ciscarpathian region to understand the spatial variability of oak growth and its climate signal better.

Impacts of Climate Change on Ecological Water Use in the Beijing–Tianjin–Hebei Region in China

The Beijing–Tianjin–Hebei region in China is experiencing a serious ecological water scarcity problem in the context of climate warming and drying. There is an urgent need for practical adaptation measures to cope with the adverse impacts of climate change and provide a scientific basis for urban water supply planning, water resource management, and policy formulation. Urban ecological water can maintain the structure and function of urban ecosystems, both as an environmental element and as a resource. Current research lacks quantitative analysis of the impact of regional meteorological factors on ecological water use at the small and medium scales. Based on the meteorological data and statistical data of water resources in the Beijing–Tianjin–Hebei (BTH) region, this paper analyzed the trend of climate change and established an ecological climatic water model using gray correlation analysis, polynomial simulation, and singular spectrum analysis to predict the ecological water consumption. And, we assessed the climatic sensitivity of ecological water use and estimated the future ecological climatic water use in the BTH region based on four climate scenarios’ data. The results showed that the average multi-year temperature was 13.2 °C with a clear upward trend from 1991 to 2020 in the BTH region. The multi-year average precipitation was 517.1 mm, with a clear shift in the period of abundance and desiccation. Ecological climatic water modeling showed that a 1 °C increase in temperature will increase ecological water use by 0.73 × 108 m3~1.09 × 108 m3 in the BTH region; for a 100 mm increase in precipitation, ecological water use will decrease by 0.49 × 108 m3~0.88 × 108 m3; under the four climate scenarios of SSP1–2.6, SSP2–4.5, SSP3–7.0, and SSP5–8.5, the regional ecological climatic water use will be 5.14 × 108 m3, 6.64 × 108 m3, 7.82 × 108 m3, and 9.06 × 108 m3 in 2035, respectively; and in 2050, the ecological climatic water use will be 8.16 × 108 m3, 9.75 × 108 m3, 10.71 × 108 m3, and 12.41 × 108 m3, respectively. The methodology and results of this study will support the quantification of climate change impacts on ecological water use in the BTH region and serve as a theoretical basis for future research on ecological water use adaptation to climate change. This study can provide a basis for the development of the overall planning of urban ecological water supply, and at the same time, it can lay a foundation for the study of measures to adapt to climate change by ecological water use.

Climatic sensitivity of seasonal ice-cover, water temperature and biogeochemical cycling in Lake 239 of the Experimental Lakes Area (ELA), Ontario, Canada

Regional climate plays an important role on in-lake physical and biogeochemical processes and determines the state of water quality and ecology of the lakes. This paper presents the result of a one-dimensional numerical modelling of lake ice cover, water temperature, as well as nutrient and phytoplankton dynamics in Lake 239 (Rawson Lake) located in the Experimental Lakes Area (ELA), Ontario, Canada. Using observed meteorological and inflow/outflow data, the Multi-year Lake simulation model (MyLake) was setup to replicate measured lake water temperature, ice-cover, dissolved organic carbon, particulate and dissolved phosphorus, and chlorophyll-a concentrations over the entire depth of the lake. The sensitivity of the lake to changes in climatic drivers, specifically to changes in surface air temperature and wind speed, was examined by incrementally changing the model input forcing for temperature and wind speed and mapping the resulting changes in the simulated outputs. The results show that lake processes are generally as sensitive to changes in wind speed as they are to changes in air temperature. Simulated changes in lake variables corresponding to projected changes in Global Climate Models (GCMs) under RCP4.5 and RCP8.5 emission scenarios reveal a general increase in lake water temperature and the corresponding decrease in lake ice thickness and ice cover duration under the changing climate. While lake water temperature increases at all depths, the shallow epilimnion layer is more sensitive to the changing climate than the deeper hypolimnion layer, reaching mean annual change value of +3.7 °C for RCP 8.5 and the 2090s as compared to the 1990s baseline period. While the simulated change in lake ice thickness reaches −20 cm by 2090s for the RCP 8.5 scenario, the corresponding change in ice-cover duration reaches -47 days. These changes are shown to result in seasonal changes in the biogeochemical cycling over the depth of the lake with projected increases in chlorophyll-a concentration during ice covered season of December to May reaching up to +0.15 mg/m3 for RCP 8.5 and the 2090s followed by a decrease during open water season of June to November reaching −0.15 mg/m3 compared to the 1990s baseline period.