Recent Warming Trend Research Articles

Relationships between freezing resistance and biochemicals in grapevine buds and canes: Different soluble carbohydrates accumulate in several cultivars during cold acclimation

Owing to recent warming trends during the growing season, wine grapevine (Vitis vinifera) production has increased in subarctic areas such as Hokkaido. However, high freezing resistance remains essential for grapevines due to the severe winter temperatures in these regions. Here, we investigated the seasonal variation in freezing resistance, as well as the water, soluble carbohydrate, proline, and total phenolic content (TPC) in the buds and canes of two V. vinifera cultivars and a Vitis riparia hybrid, Maeve. We found that freezing resistance in the buds and canes increased from fall to winter, with Maeve exhibiting higher freezing resistance than the V. vinifera cultivars during both seasons. Maeve experienced a faster rate of deacclimation, leading to comparable spring freezing resistance among all cultivars. The water content in the buds and canes of all three cultivars decreased during the fall, with Maeve showing an earlier reduction compared to the others. Most soluble carbohydrates increased in winter and decreased in spring. Notably, Maeve, which had higher winter freezing resistance, accumulated more sucrose in its buds and a higher concentration of soluble carbohydrates, particularly monosaccharides, in its canes compared to the other two cultivars. Proline and TPC levels were not linked to freezing resistance. Grapevine buds and canes appeared to accumulate soluble carbohydrates, especially monosaccharides, during winter, while reducing water content in fall to enhance freezing resistance. This study suggests that grapevine cultivars in Hokkaido may utilize different types of soluble carbohydrates to improve the freezing resistance of their buds and canes.

2023 temperatures reflect steady global warming and internal sea surface temperature variability

2023 was the warmest year on record, influenced by multiple warm ocean basins. This has prompted speculation of an acceleration in surface warming, or a stronger than expected influence from loss of aerosol induced cooling. Here we use a recent Green’s function-based method to quantify the influence of sea surface temperature patterns on the 2023 global temperature anomaly, and compare them to previous record warm years. We show that the strong deviation from recent warming trends is consistent with previously observed sea surface temperature influences, and regional forcing. This indicates that internal variability was a strong contributor to the exceptional 2023 temperature evolution, in combination with steady anthropogenic global warming.

Recent warming trends of the Greenland ice sheet documented by historical firn and ice temperature observations and machine learning

Abstract. Surface melt on the Greenland ice sheet has been increasing in intensity and extent over the last decades due to Arctic atmospheric warming. Surface melt depends on the surface energy balance, which includes the atmospheric forcing but also the thermal budget of the snow, firn and ice near the ice sheet surface. The temperature of the ice sheet subsurface has been used as an indicator of the thermal state of the ice sheet's surface. Here, we present a compilation of 4612 measurements of firn and ice temperature at 10 m below the surface (T10 m) across the ice sheet, spanning from 1912 to 2022. The measurements are either instantaneous or monthly averages. We train an artificial neural network model (ANN) on 4597 of these point observations, weighted by their relative representativity, and use it to reconstruct T10 m over the entire Greenland ice sheet for the period 1950–2022 at a monthly timescale. We use 10-year averages and mean annual values of air temperature and snowfall from the ERA5 reanalysis dataset as model input. The ANN indicates a Greenland-wide positive trend of T10 m at 0.2 ∘C per decade during the 1950–2022 period, with a cooling during 1950–1985 (−0.4 ∘C per decade) followed by a warming during 1985–2022 (+0.7 ∘ per decade). Regional climate models HIRHAM5, RACMO2.3p2 and MARv3.12 show mixed results compared to the observational T10 m dataset, with mean differences ranging from −0.4 ∘C (HIRHAM) to 1.2 ∘C (MAR) and root mean squared differences ranging from 2.8 ∘C (HIRHAM) to 4.7 ∘C (MAR). The observation-based ANN also reveals an underestimation of the subsurface warming trends in climate models for the bare-ice and dry-snow areas. The subsurface warming brings the Greenland ice sheet surface closer to the melting point, reducing the amount of energy input required for melting. Our compilation documents the response of the ice sheet subsurface to atmospheric warming and will enable further improvements of models used for ice sheet mass loss assessment and reduce the uncertainty in projections.

Estimation of genotype by environmental interaction for litter traits by reaction norm model in Taiwan Landrace sows.

The negative effects of heat stress on swine reproduction have been well documented and the recent global warming trend caused by climate change is leading to more days with high temperatures every year. This has caused a reduction in litter trait performance of Landrace sows in Taiwan, a country extending across tropical and subtropical oceanic zones. Therefore, this study developed a modified model to determine which stages of pregnancy, before, early, middle, and late, had the largest impacts of heat stress on litter traits. A reaction norm model (RNM) was used to identify sows with high resilience to heat stress for litter traits followed by analysis of the modified model. Data from Landrace sows were collected from 2 farms in Taiwan between 2008 and 2021. A total of 11,059 records were collected for total number born (TNB), number born alive (NBA), and stillborn rate (STBR). The results showed that the heritabilities of TNB, NBA, and STBR were 0.170, 0.115, and 0.077, respectively. These results were similar between the conventional model and the modified model. In the modified model, the before and early stages of sow pregnancy were the significant periods for TNB and NBA (P < 0.05), while the early and middle stages were significant for STBR (P < 0.05). According to the RNM results, the heritability estimates for TNB, NBA, and STBR were 0.23 to 0.11, 0.18 to 0.08, and 0.10 to 0.04, respectively, showing a decrease from low temperature-humidity index (THI) to high THI. The minimum genetic correlations between the highest and the lowest THI for TNB, NBA, and STBR were 0.85, 0.64, and 0.80, respectively. The results of the RNM for breeding value showed re-ranking across THI values. In conclusion, similar results were obtained for heritability when the model was modified for heat stress estimation. Yet re-ranking of breeding values across THI could help farmers to select not only for improved litter trait performance but also for heat stress resilience of Landrace sows in Taiwan.

Investigating the thermal state of permafrost with Bayesian inverse modeling of heat transfer

Abstract. Long-term measurements of permafrost temperatures do not provide a complete picture of the Arctic subsurface thermal regime. Regions with warmer permafrost often show little to no long-term change in ground temperature due to the uptake and release of latent heat during freezing and thawing. Thus, regions where the least warming is observed may also be the most vulnerable to permafrost degradation. Since direct measurements of ice and liquid water contents in the permafrost layer are not widely available, thermal modeling of the subsurface plays a crucial role in understanding how permafrost responds to changes in the local energy balance. In this work, we first analyze trends in observed air and permafrost temperatures at four sites within the continuous permafrost zone, where we find substantial variation in the apparent relationship between long-term changes in permafrost temperatures (0.02–0.16 K yr−1) and air temperature (0.09–0.11 K yr−1). We then apply recently developed Bayesian inversion methods to link observed changes in borehole temperatures to unobserved changes in latent heat and active layer thickness using a transient model of heat conduction with phase change. Our results suggest that the degree to which recent warming trends correlate with permafrost thaw depends strongly on both soil freezing characteristics and historical climatology. At the warmest site, a 9 m borehole near Ny-Ålesund, Svalbard, modeled active layer thickness increases by an average of 13 ± 1 cm K−1 rise in mean annual ground temperature. In stark contrast, modeled rates of thaw at one of the colder sites, a borehole on Samoylov Island in the Lena River delta, appear far less sensitive to temperature change, with a negligible effect of 1 ± 1 cm K−1. Although our study is limited to just four sites, the results urge caution in the interpretation and comparison of warming trends in Arctic boreholes, indicating significant uncertainty in their implications for the current and future thermal state of permafrost.

An Approach for Selecting Observationally-Constrained Global Climate Model Ensembles for Regional Climate Impacts and Adaptation Studies in Canada

Given the growing number of global climate models (GCMs) with simulations available for impacts and adaptation studies, methods have been introduced to select models that are ‘fit-for-purpose’. This study applies a GCM selection process to historical and future climate projections from 38 and 43 GCMs contributing to the fifth and sixth phases of the Coupled Model Intercomparison Project (CMIP5 and CMIP6). Models are selected based on historical performance, with a further selection step targeted at reducing interdependencies between closely related model variants and ensemble members. Ten performance measures are calculated based on climatological statistics (mean, standard deviation, and seasonal cycle) of three climate variables (precipitation, sea level pressure, and surface air temperature (SAT)), as well as SAT warming trend for the 1985–2014 period. Performance is assessed over Canada and six Canadian sub-regions, at both annual and seasonal timescales. As initial-condition members and minor variants of GCMs are not independent, a representative democracy approach – using ensemble averages of initial-condition members and including only the best performance model among minor variants – is employed to reduce redundancy in selected subsets. There is a strong correlation between recent warming trends and future warming projections across Canada; therefore, observed SAT warming trends are recognized as important observational-constraints to aid in model selection. By removing “hot models” that fail to reproduce the historical SAT warming trend, a representative subset of observationally-constrained GCMs projects lower annual SAT than model democracy (using all model runs assuming independence and equal plausibility) over Canada and six Canadian sub-regions for 2071–2100.

Shrub-mediated effects on soil nitrogen determines shrub-herbaceous interactions in drylands of the Tibetan Plateau.

Shrub promotes the survival, growth and reproduction of understory species by buffering the environmental extremes and improving limited resources (i.e., facilitation effect) in arid and semiarid regions. However, the importance of soil water and nutrient availability on shrub facilitation, and its trend along a drought gradient have been relatively less addressed in water-limited systems. We investigated species richness, plant size, soil total nitrogen and dominant grass leaf δ13C within and outside the dominant leguminous cushion-like shrub Caragana versicolor along a water deficit gradient in drylands of Tibetan Plateau. We found that C. versicolor increased grass species richness but had a negative effect on annual and perennial forbs. Along the water deficit gradient, plant interaction assessed by species richness (RIIspecies) showed a unimodal pattern with shift from increase to decrease, while plant interaction assessed by plant size (RIIsize) did not vary significantly. The effect of C. versicolor on soil nitrogen, rather than water availability, determined its overall effect on understory species richness. Neither the effect of C. versicolor on soil nitrogen nor water availability affected plant size. Our study suggests that the drying tendency in association with the recent warming trends observed in drylands of Tibetan Plateau, will likely hinder the facilitation effect of nurse leguminous shrub on understories if moisture availability crosses a critical minimum threshold.

Recent Warming Trends in the Arabian Sea: Causative Factors and Physical Mechanisms

In recent years, and particularly from 2000 onwards, the North Indian Ocean (NIO) has been acting as a major sink of ocean heat that is clearly visible in the sub-surface warming trend. Interestingly, a part of the NIO—the Arabian Sea (AS) sector—witnessed dramatic variations in recent sub-surface warming that has direct repercussion on intense Tropical Cyclone (TC) activity. This study investigated the possible causative factors and physical mechanisms towards the multi-decadal warming trends in surface and sub-surface waters over the AS region. Responsible factors towards warming are examined using altimetric observations and reanalysis products. This study used ORAS5 OHC (Ocean Heat Content), derived meridional and zonal heat transport, currents, temperature, salinity, Outgoing Longwave Radiation (OLR), and air-sea fluxes to quantify the OHC build-up and its variability at water depths of 700 m (D700) and 300 m (D300) during the past four decades. The highest variability in deeper and upper OHC is noticed for the western and southern regions of the Indian Ocean. The warming trend is significantly higher in the deeper regions of AS compared to the upper waters, and relatively higher compared to the Bay of Bengal (BoB). Increased OHC in AS show good correlation with decreased OLR in the past 20 years. An analysis of altimetric observations revealed strengthening of downwelling Kelvin wave propagation leading to warming in eastern AS, mainly attributed due to intrusion of low saline water from BoB leading to stratification. Rossby wave associated with deepening of thermocline warmed the southern AS during its propagation. Heat budget analysis reveals that surface heat fluxes play a dominant role in warming AS during the pre-monsoon season. Increasing (decreasing) trend of surface heat fluxes (vertical entrainment) during 2000–2018 played a significant role in warming the southeastern sector of AS.

Dendroclimatic Reconstruction of Mean Annual Temperatures over Treeline Regions of Northern Bhutan Himalayas

The Himalayan region is likely particularly exposed to climate change indicated by the high regional rate of change. The number of high-resolution, well-calibrated, and long-term paleoclimate reconstructions are however regrettably few, to set this change in a longer-term context. The dendroclimatic reconstructions over Himalaya that do exist have only reconstructed summer season temperatures, and rarely or never attempted to reconstruct mean annual temperatures. The paucity of long meteorological records is a matter of concern when developing chronologies of climate sensitive tree-ring data in Bhutan, but the chronologies would theoretically be of high potential for extending short meteorological records back in time using trees in high-elevation ecotones. The objectives of this study were to explore dendroclimatic signals in tree-ring width chronologies of Abies densa growing in these extreme ecotones and to reconstruct, if possible, annual temperatures over Northern Bhutan. A point-by-point regression analysis revealed that the regional composite chronology was significantly and positively correlated with temperatures of all months of the current year, i.e., January to December. The chronology was highly correlated with annual temperatures (calibration period R = 0.67 and validation period R = 0.50; p &lt; 0.001) allowing a reconstruction of temperature over Northern Bhutan (NB-TEMR). The NB-TEMR reveals some common variations with summer temperature reconstructions of the Northern Hemisphere as well as the Himalayan region, particularly w.r.t to the recent warming trend. The reconstruction covers the period of 1765 to 2017. This reconstruction reveals a warming trend since 1850 with higher rates of warming 1935 to 2017, but with a pause around 1940–1970. The warming is consistent with reduced volcanic activity and increase of greenhouse gases. We anticipate that our new reconstruction of annual mean temperature could be an important contribution for future climate change studies and assessments of climate models.

Changing flood dynamics in Norway since the last millennium and to the end of the 21st century

• All GCMs except MIROC-ESM simulate a higher mean temperature in Medieval Climate Anomaly (MCA) period than Little Ice Age (LIA) period, while simulated annual precipitation varies a lot in different GCMs and catchments. • No significant change of flood characteristics during the last millennium from ensemble-mean results. • In future, we will have an extraordinary shift in flood seasonality and generating processes, and flood frequency increase in most of the study catchments in Norway. • Climate projections represent the largest contribution to overall uncertainty in the projected changes in hydrological extremes for most of the catchments. With the recent warming trend over Europe and the Arctic, the Nordic regions have experienced more frequent and damaging extreme hydrological events which are anticipated to increase towards the end of the 21st century. Despite explicit trends, large variations have been observed across basins and regions when it comes to precipitation and floods hinting at a strong natural hydroclimatic variability that further complicates any assessment of potential future changes. In this study, we aim to better understand how climate variability links with the current extremes and future projections of floods in Norway in the context of the last millennium and the future. Specifically, we simulate over 1000 years (850–2099) daily discharge and floods at 34 catchments over five regions of Norway from the last millennium (including a warm period and a cold period; 850–1849) to the end of the 21st century by an ensemble model-chain method including four global climate models (GCMs), two bias-correction methods and two hydrological models. The modelling results show (i) all GCMs except MIROC-ESM simulate a higher mean temperature in Medieval Climate Anomaly (MCA) period than Little Ice Age (LIA) period, while simulated annual precipitation varies a lot in different GCMs and catchments, (ii) no significant change of flood characteristics during the last millennium from ensemble-mean results, (iii) in future, we will have an extraordinary shift in flood seasonality and generating processes, and flood frequency increase in most of the study catchments in Norway, and (iv) climate projections represent the largest contribution to overall uncertainty in the projected changes in hydrological extremes for most of the catchments.

Lipidomics-Assisted GWAS (lGWAS) Approach for Improving High-Temperature Stress Tolerance of Crops.

High-temperature stress (HT) over crop productivity is an important environmental factor demanding more attention as recent global warming trends are alarming and pose a potential threat to crop production. According to the Sixth IPCC report, future years will have longer warm seasons and frequent heat waves. Thus, the need arises to develop HT-tolerant genotypes that can be used to breed high-yielding crops. Several physiological, biochemical, and molecular alterations are orchestrated in providing HT tolerance to a genotype. One mechanism to counter HT is overcoming high-temperature-induced membrane superfluidity and structural disorganizations. Several HT lipidomic studies on different genotypes have indicated the potential involvement of membrane lipid remodelling in providing HT tolerance. Advances in high-throughput analytical techniques such as tandem mass spectrometry have paved the way for large-scale identification and quantification of the enormously diverse lipid molecules in a single run. Physiological trait-based breeding has been employed so far to identify and select HT tolerant genotypes but has several disadvantages, such as the genotype-phenotype gap affecting the efficiency of identifying the underlying genetic association. Tolerant genotypes maintain a high photosynthetic rate, stable membranes, and membrane-associated mechanisms. In this context, studying the HT-induced membrane lipid remodelling, resultant of several up-/down-regulations of genes and post-translational modifications, will aid in identifying potential lipid biomarkers for HT tolerance/susceptibility. The identified lipid biomarkers (LIPIDOTYPE) can thus be considered an intermediate phenotype, bridging the gap between genotype–phenotype (genotype–LIPIDOTYPE–phenotype). Recent works integrating metabolomics with quantitative genetic studies such as GWAS (mGWAS) have provided close associations between genotype, metabolites, and stress-tolerant phenotypes. This review has been sculpted to provide a potential workflow that combines MS-based lipidomics and the robust GWAS (lipidomics assisted GWAS-lGWAS) to identify membrane lipid remodelling related genes and associations which can be used to develop HS tolerant genotypes with enhanced membrane thermostability (MTS) and heat stable photosynthesis (HP).

Partly decoupled tree-ring width and leaf phenology response to 20th century temperature change in Sweden

The recent warming trend, and associated shifts in growing season length, challenge the principle of uniformitarianism, i.e., that current relations are persistent over time, and complicates the uncritical inferences of past climate from tree-ring data. Here we conduct a comparison between tree-ring width chronologies of Pinus sylvestris L. (Scots pine), Picea abies (L.) Karst. (Norway spruce) and Betula pubescens Ehrh. (Downy birch) and phenological observations (budburst and leaf senescence) of Fagus sylvatica L. (European beech), Quercus robur L. (European oak), Betula sp. (Birch), Norway spruce and Scots pine) in Sweden to assess to what extent the tree-ring width–temperature relationship and the timing of phenological phases are affected by increased temperature. Daily meteorological observations confirm a prolongation of the thermal growing season, most consistently observed as an earlier onset of around 1–2 weeks since the beginning of the 20th century. Observations of budburst closely mimic this pattern, with budburst of the deciduous trees occurring 1–2.5 weeks earlier. In contrast to the changes seen in phenology and observational temperature data, the tree-ring width–temperature relationships remain surprisingly stable throughout the 20th century. Norway spruce, Scots pine and Downy birch all show consistently significant correlations with at least one 30 day-long window of temperature starting in late June–early July season. Norway spruce displays the largest degree of stability, with a consistent 60 day-long temperature window with significant correlation starting around Julian calendar day 150. Thus, our results suggest that the principle of uniformitarianism is not violated during the period covered by modern meteorological observations. Further research is needed to determine at what thresholds the temperature sensitivity of these species may alter or deteriorate as a consequence of the ongoing climate change.

2021 Texas cold snap: Manifestation of natural variability and a recent warming trend

In this paper, we demonstrate that the extreme cold snap in Texas in February 2021 resulted from a large-scale background circulation anomaly over the North Pacific and North America that was a manifestation of both natural variability (namely, a negative Pacific–North American pattern, PNA) and a warming trend that began in the late 1990s. Numerical experiments revealed that the negative PNA pattern could be driven by negative (La Niña-like) sea surface temperature (SST) anomalies in the equatorial eastern Pacific on an interannual–decadal timescale and the SST warming trend in the subtropical North Atlantic on a longer timescale. We propose that the excitation of the most unstable mode of the Northern Hemisphere winter, which exhibits a combined negative PNA and positive East Atlantic pattern resulting from SST anomalies and trends, leads to the dominance of the large-scale circulation anomaly observed in February 2021 and over the last few decades.Our study demonstrated the key role of extratropical wave activity and the intrinsic mode in causing the extreme cold in North America. The arguments favoring polar or tropical influences may partially explain the source of variability, considering that extratropical weather and climate variability could be modulated by not only polar or tropical perturbations but also the enhanced tropical–extratropical interaction and mid-latitude instability. A systematic approach involving both empirical diagnostics and a suite of carefully designed numerical experiments is required to determine the relative influence of various sources of variability.Regarding future changes, models of the Coupled Model Intercomparison Project Phase 6 project a weakening, rather than an enhancement, of the negative PNA pattern that favors the occurrence of cold snaps despite failing to simulate the observed enhanced trend since the late 1990s.

Climate‐driven substitution of foundation species causes breakdown of a facilitation cascade with potential implications for higher trophic levels

Abstract Climate change can alter ecological communities both directly, by driving shifts in species distributions and abundances, and indirectly by influencing the strength and direction of species interactions. Within benthic marine ecosystems, foundation species such as canopy‐forming macro‐algae often underpin important cascades of facilitative interactions. We examined the wider impacts of climate‐driven shifts in the relative abundances of foundation species within a temperate reef system, with particular focus on a habitat cascade whereby kelp facilitate epiphytic algae that, in turn, facilitate mobile invertebrates. Specifically, we tested whether the warm‐water kelp Laminaria ochroleuca, which has proliferated in response to recent warming trends, facilitated a secondary habitat‐former (epiphytic algae on stipes) and associated mobile invertebrates, to the same degree as the cold‐water kelp Laminaria hyperborea. The facilitative interaction between kelp and stipe‐associated epiphytic algae was dramatically weaker for the warm‐water foundation species, leading to breakdown of a habitat cascade and impoverished associated faunal assemblages. On average, the warm‐water kelp supported &gt;250 times less epiphytic algae (by biomass) and &gt;50 times fewer mobile invertebrates (by abundance) than the cold‐water kelp. Moreover, by comparing regions of pre‐ and post‐range expansion by L. ochroleuca, we found that warming‐impacted kelp forests supported around half the biomass of epiphytic algae and one‐fifth of the abundance of mobile invertebrates, per unit area, compared with unimpacted forests. We suggest that disruption to this facilitation cascade has the potential to impact upon higher trophic levels, specifically kelp forest fishes, through lower prey availability. Synthesis. Climate‐driven shifts in species' distributions and the relative abundances of foundation organisms will restructure communities and alter ecological interactions, with consequences for ecosystem functioning. We show that climate‐driven substitutions of seemingly similar foundation species can alter local biodiversity and trophic processes in temperate marine ecosystems.

Carbon dioxide fluxes of a mountain grassland: Drivers, anomalies and annual budgets

The potential of grasslands to mitigate climate change by carbon (C) sequestration in soils depends on agricultural management and the response of the grassland C cycle to a warming and more variable climate. A 15-year time series of eddy covariance carbon dioxide (CO2) flux measurements on a medium-intensively managed grassland at 1000 m above sea level in Switzerland was analysed to assess how CO2 fluxes respond to environmental drivers as well as grazing and cutting events. Further, the effects of management, recent warming trends and anomalous weather conditions on the annual C sequestration potential were assessed. To this end, C budgets including atmospheric and management-related C fluxes (fertilization, cutting/grazing) were estimated. Generally, the main environmental drivers of CO2 fluxes were light and temperature. The removal of the aboveground canopy by management significantly reduced photosynthesis and induced a saturation in the photosynthetic response to light at lower intensities compared to periods without management. Ecosystem respiration remained largely unaffected by management. With a net ecosystem exchange of −357 (± 76) g C m−2 year−1 and a net biome production of −154 (± 80) g C m−2 year−1 (including management C fluxes), the grassland on average acted as a net C sink. Recent climate warming favors spring CO2 assimilation due to earlier starting vegetation periods. However, the warming also resulted in an increased ecosystem respiration. Further, anomalous and especially unfavorable weather conditions for photosynthesis and regrowth following harvest events induced several periods of an anomalously increased net CO2 release. In the year 2015, such release anomalies contributed to an annual net C loss. Under future climatic conditions, the C sequestration potential at the mountain site will depend on the extent to which spring photosynthesis is offset by such climate-management interactions and a warming-induced increase in ecosystem respiration.

2021 Texas Cold Snap: Manifestation of Natural Variability and a Recent Warming Trend

2021 Texas Cold Snap: Manifestation of Natural Variability and a Recent Warming Trend

Shifting seasonality of cyclones and western boundary current interactions in Bay of Bengal as observed during Amphan and Fani

In recent years, the seasonal patterns of Tropical Cyclones (TC) in the Bay of Bengal have been shifting. While tropical depressions have been common in March–May (spring), they typically have been relatively weaker than the TCs during October–December. Here we show that the spatial pattern of recent warming trends during the last two decades in the southwestern Bay has allowed for stronger springtime pre-monsoon cyclones such as Amphan (May 2020, Super Cyclone) and Fani (April–May 2019, Extremely Severe Cyclone). The tracks of the pre-monsoon cyclones shifted westward, concurrent with an increasing rate of warming. This shift allowed both Fani and Amphan tracks to cross the northeastward warm Western Boundary Current (WBC) and associated warm anti-cyclonic eddies, while the weaker Viyaru (April 2013, Cyclonic Storm) did not interact with the WBC. A quantitative model linking the available along-track heat potential to cyclone’s intensity is developed to understand the impact of the WBC on cyclone intensification. The influence of the warming WBC and associated anti-cyclonic eddies will likely result in much stronger springtime TCs becoming relatively common in the future.

A Secular Shift of the Madden‐Julian Oscillation and Its Relation to Western Pacific Ocean Warming

AbstractIn the context of global warming, understanding changes in the Madden‐Julian Oscillation (MJO) is of great importance, because of its worldwide impact on surface weather and climate. By analyzing the temporal evolution of the phase relationship between Kelvin waves and the MJO, we find a secular phase shift of the MJO after year 2000, at which the MJO exhibits an eastward extension over the Maritime Continent and the Western Pacific Ocean. Further, we examine the influence of sea surface temperature (SST) variations on the anomalous convection and Kelvin waves, and demonstrate that the recent warming trend of the Western Pacific SST is a factor causing the changes of the MJO over this region. The results deepen our understanding of recent modeling and observational studies about the changes of the MJO and confirm the enhanced activity of the MJO over the past few decades.

Long-Term Observations of Interannual and Decadal Variation of Sea Surface Temperature in the Taiwan Strait

Long-term observations of interannual and decadal variation of sea surface temperature (SST) in the Taiwan Strait (TS) were studied for the period 1870–2018; the climatology data were obtained from the Met Office Hadley Centre, UK. In the study period, the highest annual mean and lowest SST observed were 25.3°C in 1998 and 22.4°C in 1919, respectively. Six distinct regimes were identified. The first regime of fairly stable or slightly cooling SST lasted through the 1920s. The two regime shifts of 1919 to 1945 and 1976–1977 to 1998 led to the two fast warming trends of 2.0°C in 26 years, from 22.5°C in 1919 up to 24.5°C in 1945, and of 2.4°C in 22 years, from 22.9°C in 1977 up to 25.3°C in 1998, respectively. Another two regime shifts initiated in 1945 (1945–1976) and 1998–1999 (1998–2011) that led to 1.6°C and 1.0°C cooling, respectively. A recent and fast warming trend with 0.63°C/decade suggested that the warming hiatus from 1998 to 2011 faded away since 2012. The spatial distribution of climate trends through the decades across the TS revealed a strong spatial gradient along the Strait. In the north (southern East China Sea), the magnitude and rate of the overall SST warming between 1870 and 2018 were approximately 1.5 times than those in the south (northern South China Sea).

Contextualizing Thermal Effluent Impacts in Narragansett Bay Using Landsat-Derived Surface Temperature

This work utilizes remotely sensed thermal data to understand how the release of thermal pollution from the Brayton Point Power Station (BPPS) affected the temperature behavior of Narragansett Bay. Building upon previous work with Landsat 5, a multi-satellite analysis is conducted that incorporates 582 scenes from Landsat 5, Landsat 7, and Landsat 8 over 1984–2021 to explain seasonal variability in effluent impacts, contrast data after the effluent ceased in 2011, identify patterns in temperature before and after effluent ceased using unsupervised learning, and track how recent warming trends compare to the BPPS impact. Stopping the thermal effluent corresponds to an immediate cooling of 0.26 ± 0.1°C in the surface temperature of Mt. Hope Bay with respect to the rest of Narragansett Bay with greater cooling of 0.62 ± 0.2°C found near Brayton Point; though, cooling since the period of maximal impact (1993–2000) totals 0.53 ± 0.2°C in Mt. Hope Bay and 1.04 ± 0.2°C at Brayton Point. During seasons with lower solar radiation (winter) and lower mean river input (autumn and late summer), the BPPS effluent impact is more prominent. The seasonal differences between the high impact and low impact periods indicate that river input played an important role in the heat balance when emissions were lower, but surface fluxes dominated when emissions were higher. Putting the BPPS effluent in context, Landsat data indicates that Narragansett Bay warmed 0.5–1.2°C over the period of measurement at an average rate of 0.23 ± 0.1°C/decade and that net warming in Mt. Hope Bay is near zero. This trend implies that Narragansett Bay has experienced climatic warming over the past four decades on the scale of the temperature anomaly in Mt. Hope Bay caused by the BBPS effluent.