Air Temperature Trends Research Articles

Quantifying the internal variability in multi-decadal trends of spring surface air temperature over mid-to-high latitudes of Eurasia

This study investigates the influences of internal climate variability (ICV) on Eurasian spring (March–May) surface air temperature (SAT) trends based on a 30-member ensemble of the Community Earth System Model version 1 (CESM1) from 1979 to 2014. The SAT trends over the mid-high latitude Eurasia vary considerably among individual simulations, indicating a large impact of ICV on SAT trends at regional scales. The leading pattern of internally generated SAT trend variability over Eurasia among the 30 SAT trends displays same sign distribution over the mid-high latitudes of Eurasia. This pattern is associated with the Northern Hemisphere annular mode (NAM) that accounts for about 1/3 of total variance of the spring sea level pressure (SLP) trends. The second pattern of internally generated SAT trend variability features a dipole structure, accompanied by prominent circulation changes over the North Atlantic and Europe. Internal dynamics account for approximately 40–70% of the observed warming over the central Eurasia and the Russian Far East. A dynamical adjustment methodology is employed to remove the effects of internal atmospheric circulation variability. Dynamical adjustment greatly reduces the spread of SAT trends within the ensemble and brings both the simulated and observed trends closer to the ensemble mean. Changes in the Barents–Kara Sea ice and Eurasian snow cover contribute to the remaining spread in SAT trends over the north coast of Russia and in the region north of the Caspian Sea, respectively. Both dynamics and thermodynamics contribute to the Barents–Kara Sea ice and Eurasian snow cover trends.

Climate From the McMurdo Dry Valleys, Antarctica, 1986–2017: Surface Air Temperature Trends and Redefined Summer Season

AbstractThe weather of the McMurdo Dry Valleys, Antarctica, the largest ice‐free region of the Antarctica, has been continuously monitored since 1985 with currently 14 operational meteorological stations distributed throughout the valleys. Because climate is based on a 30‐year record of weather, this is the first study to truly define the contemporary climate of the McMurdo Dry Valleys. Mean air temperature and solar radiation based on all stations were −20°C and 102 W m−2, respectively. Depending on the site location, the mean annual air temperatures on the valleys floors ranged between −15°C and −30°C, and mean annual solar radiation varied between 72 and 122 W m−2. Surface air temperature decreased by 0.7°C per decade from 1986 to 2006 at Lake Hoare station (longest continuous record), after which the record is highly variable with no trend. All stations with sufficiently long records showed similar trend shifts in 2005 ±1 year. Summer is defined as November through February, using a physically based process: up‐valley warming from the coast associated with a change in atmospheric stability.

Circulation Mechanisms Generating Temperature Anomalies Over the Territory of Asian Russia

This paper studies the changes in winter air temperatures in the Siberian sector of the northern hemisphere (60–120° E) over a long-term period of 1947–2017. A positive trend in air temperature (0.3°C/10 years) was revealed. An analysis of the magnitude and frequency of temperature anomalies also confirms an increase in surface temperature. The distribution of large positive and negative temperature anomalies was investigated. Centers of the largest recurrence of large negative anomalies were located in the south and south-west of the study area. A maximum number of negative anomalies were observed in December. Large positive anomalies (the highest frequency in January) were observed throughout the territory under consideration, and extremely large anomalies were found only at 20% of the stations. The largest number of anomalies in the period of 1947–2017 was observed at the Irkutsk station. Based on the analysis of elementary circulation mechanisms (classification by B.L. Dzerdzeevskii), a relationship was established between the atmospheric circulation and the distribution of air temperature anomalies. It was concluded that the temperature regime in the winter months was formed under the influence of 26 elementary circulation mechanisms, combined into seven groups. The meridional circulation prevailed (75% of cases). The elementary circulation mechanisms of the meridional northern circulation group were all characterized by the presence of blockings and intrusions of southern cyclones into the study area. In general, over the past two decades, an increase in duration of macrocirculation processes resulting in the inter-latitudinal air mass exchange has been revealed.

A 54-year record of changes at Chalaati and Zopkhito glaciers, Georgian Caucasus, observed from archival maps, satellite imagery, drone survey and ground-based investigation

Individual glacier changes are still poorly documented in the Georgian Caucasus. In this paper, the change of Chalaati and Zopkhito glaciers in Georgian Caucasus has been studied between 1960 and 2014. Glacier geometries are reconstructed from archival topographic maps, Corona and Landsat images, along with modern field surveys. For the first time in the Georgian Caucasus aerial photogrammetric survey of both glacier termini was performed (2014) using a drone or Unmanned Aerial Vehicle, where high-resolution orthomosaics and digital elevation models were produced. We show that both glaciers have experienced area loss since 1960: 16.2±4.9 per cent for Chalaati Glacier and 14.6±5.1 per cent for Zopkhito Glacier with corresponding respective terminus retreat by ~675 m and ~720 m. These were accompanied by a rise in the equilibrium line altitudes of ~35 m and ~30 m, respectively. The glacier changes are a response to regional warming in surface air temperature over the last half century. We used a long-term temperature record from the town of Mestia and short-term meteorological observations at Chalaati and Zopkhito glaciers to estimate a longer-term air temperature record for both glaciers. This analysis suggests an increase in the duration of the melt season over the 54-year period, indicating the importance of summertime air temperature trends in controlling glacier loss in the Georgian Caucasus. We also observed supra-glacial debris cover increase for both glaciers over the last half century: from 6.16±6.9 per cent to 8.01±6.8 per cent for Chalaati Glacier and from 2.80±6.3 per cent to 8.53±5.7 per cent for Zopkhito Glacier.

Geography and Morphology Affect the Ice Duration Dynamics of Northern Hemisphere Lakes Worldwide

AbstractClimate change continues to diminish ice cover duration for Northern Hemisphere lakes. However, the differential loss of lake ice duration for various types of lakes across the globe is not well established. In this study, we used time series of ice duration data (average length = 51 years) for 220 globally distributed Northern Hemisphere lakes to determine how local climate trends, geographical location, and physical properties of lakes affect their ice cover trends. Ice duration dynamics were influenced by surface air temperature trends, lake geography, and morphology. Deeper lakes, located at lower elevations, western longitudes, and lower latitudes, experienced the greatest reductions in ice cover over their time series. These results indicate that despite widespread patterns of warming, the individual features of lakes can determine how rapidly they are losing ice cover and may prove informative for future modeling and conservation efforts.

The role of internal variability in climate change projections of North American surface air temperature and temperature extremes in CanESM2 large ensemble simulations

Recent studies indicated that the internal climate variability plays an important role in various aspects of projected climate changes on regional and local scales. Here we present results of the spreads in projected trends of wintertime North American surface air temperature and extremes indices of warm and cold days over the next half-century, by analyzing a 50-member large ensemble of climate simulations conducted with CanESM2. CanESM2 simulations confirm the important role of internal variability in projected surface temperature trends as demonstrated in previous studies. Yet the spread in North American warming trends in CanESM2 is generally smaller than those obtained from CCSM3 and ECHAM5 large ensemble simulations. Despite this, large spreads in the climate means as well as climate change trends of North American temperature extremes are apparent in CanESM2, especially in the projected cold day trends. The ensemble mean of forced climate simulations reveals high risks of warm days over the western coast and northern Canada, as well as a weakening belt of cold days extending from Alaska to the northeast US. The individual ensemble members differ from the ensemble mean mainly in magnitude of the warm day trends, but depart considerably from the ensemble mean in spatial pattern and magnitude of the cold day trends. The signal-to-noise ratio pattern of the warm day trend resembles that of the surface air temperature trend, with stronger signals over northern Canada, Alaska, and the southwestern US than the midsection of the continent. The projected cold day patterns reveal strong signals over the southwestern US, northern Canada, and the northeastern US. In addition, the internally generated components of mean and extreme temperature trends exhibit spatial coherences over North America, and are comparable to their externally forced trends. The large-scale atmospheric circulation-induced temperature variability influences these trends. Overall, our results suggest that climate change trends of North American temperature extremes are likely very uncertain and need to be applied with caution.

Assessment of anomalies and effects of climate change on reference evapotranspiration and water requirement in pistachio cultivation areas in Iran

Climate change is a major challenge for the agricultural sector. In this study, the effects of climate change on reference evapotranspiration and water requirement in pistachio cultivation areas in Iran were investigated. From observational data (1980–2018) as the baseline period and simulated data (2020–2080) under RCP, scenarios were used for the future period based on MarkSimGCM database. The results showed that in the baseline period, there were an increasing trend for annual air temperature and a decreasing trend for annual precipitation in pistachio cultivation areas in Iran. Reference evapotranspiration and water requirement will deviate in the future under the RCP8.5 and RCP4.5 scenarios from the baseline period. So, under RCP8.5 and RCP4.5, reference evapotranspiration will increase by 112 and 79 mm, respectively, compared with the baseline period. The highest water requirement in pistachio trees will occur in mid-growth stage (June–September), so that, under RCP8.5 and RCP4.5, the increase will be 114 and 82 mm, respectively, compared with the baseline period. From the spatial distribution, the highest amount of reference evapotranspiration and water requirement will occur in lowland and southern half of pistachio cultivation areas, especially in Kerman province. Increasing air temperature and consequently increasing reference evapotranspiration and increasing water requirement will be a danger alarm for water resources in the dry cultivation pistachio areas in Iran. According to projections, the shortage of water will intensify in the future, and as a result of climate change, many parts of the pistachio cultivation areas in Iran will be lost.

Influence of Climate Change on the Thermal Condition of Yakutia’s Permafrost Landscapes (Chabyda Station)

This paper presents the results of 39 years of observations conducted at the Chabyda station to monitor the thermal state of permafrost landscapes under current climatic warming. The analysis of long-term records from weather stations in the region has revealed one of the highest increasing trends in mean annual air temperature in northern Russia. The partitioning of the energy balance in different landscape units within the study area has been analyzed. Quantitative relationships in the long-term variability of ground thermal parameters, such as the ground temperature at the bottom of the active layer and seasonal thaw depth, have been established. The ground temperature dynamics within the depth of zero annual amplitude indicates that both warm and cold permafrost are thermally stable. The short-term variability of the snow accumulation regime is the main factor controlling the thermal state of the ground in permafrost landscapes. The depth of seasonal thaw is characterized by low interannual variability and exhibits little response to climate warming, with no statistically significant increasing or decreasing trend. The results of the ground thermal monitoring can be extended to similar landscapes in the region, providing a reliable basis for predicting heat transfer in natural, undisturbed landscapes.

Recent warming of Tonle Sap Lake, Cambodia: Implications for one of the world’s most productive inland fisheries

AbstractTonle Sap Lake in Cambodia is arguably the world's most productive freshwater ecosystems, as well as the dominant source of animal protein for the country. The rapid rise of hydropower schemes, deforestation, land development and climate change impacts in the Mekong River Basin, however, now represent serious concerns in regard to Tonle Sap Lake's ecological health and its role in future food security. To this end, the present study identifies significant recent warming of lake temperature and discusses how each of these anthropogenic perturbations in Tonle Sap's floodplain and the Mekong River Basin may be influencing this trend. The lake's dry season monthly average temperature increased by 0.03°C/year between 1988 and 2018, being largely in synchrony with warming trends of the local air temperature and upstream rivers. The impacts of deforestation and agriculture development in the lake's floodplain also exhibited a high correlation with an increased number of warm days observed in the lake, particularly in its southeast region (agriculture R2 = .61; deforestation R2 = .39). A total of 79 dams, resulting in 72 km3 of volumetric water capacity, were constructed between 2003 and 2018 in the Mekong River Basin. This dam development coincided with a decreasing trend in the number of dry season warm days per year in the lower Mekong River, while Tonle Sap Lake's number of dry season warm days continued to increase during this same period. The present study revealed that Tonle Sap Lake's temperature trends are highly influenced by temperature trends in the local climate, agriculture development and deforestation of the lake's watershed. Although there were no noticeable impacts observed from upstream dam development in the Mekong River Basin, local‐to‐regional agricultural and land management of the lake's watershed appear to be effective strategies for maintaining a stable thermal regime in the lake in order to facilitate maximum ecosystem health.

Sensitivity of mountain catchments to global warming: a case study of the San Basin, Poland

AbstractIn changing climatic conditions with rising surface air temperatures mountain regions with their characteristic environment and accumulated snow deserve special attention and sustainable management. To investigate the sensitivity of mountain catchments to global warming, this study explores potential trends for hydro‐climatic variables between 1957 and 2016 (60 years). Based on the Mann‐Kendall test results, upward trends in air temperature were found from April to August; they are accompanied by less frequent but significant trends in precipitation (P), with increases in P for January and May, but a decrease for December. For river flow, significant upward trends were identified only for January, in line with P trends. In addition, comparative analyses of changes for two 30‐year periods (1987–2016 vs. 1957–1986) corroborate the main change directions and provide detailed information for more realistic future land and water management in the mountain catchments studied.

The effect of human land use change in the Hadley Centre attribution system

AbstractWe have investigated the effects of land use on past climate change by means of a new 15‐member ensemble of the HadGEM3‐A‐N216 model, usually used for event attribution studies. This ensemble runs from 1960 to 2013, and includes natural external climate forcings with the addition of human land use changes. It supports previously‐existing ensembles, either with only natural forcings, or with all forcings (both anthropogenic and natural, including land use changes), in determining the contribution to the change in risk of extreme events made by land use change. We found a significant difference in near‐surface air temperature trends over land, attributable to the effects of human land use. The main part of the signal derives from a relative cooling in Arctic regions which closely matches that of deforestation. This cooling appears to spread by polar amplification. A similar pattern of change is seen in latent heat flux trend, but significant rainfall change is almost entirely absent.

Variability and Trend of Air Temperature and Rainfall at Ribeirão do Lobo Hydrographic Basin, Brazil

Climate changes have been observed all over the world and are pointed out as responsible to impact the natural resources, especially the amount and the quality of the water in a hydrographic basin. Thus, the present research aimed to analyze the variability and trends of air temperature and rainfall data in the Hydrographic Basin of the Ribeirão do Lobo, São Paulo state, Brazil. The weather data from 1988 to 2017 were collected in the Center of Water Resources and Environment Studies of the University of São Paulo (CRHEA), and in five rainfall stations of the National Water Agency of Brazil (ANA) spread all over the basin. To identify climate changes were applied the simple regression, the run test, the Mann-Kendall and modified Mann-Kendall tests. The results showed significant positive trends in air temperature, especially in the annual period and during the third quarter with rising up to 0.068 °C year-1. Significant increases were verified to minimum, maximum and mean air temperature, which suggests possible climate changes during the period in the analysis. To the rainfall data, periods with positive and negative trends were found, although, most of the time the trends were non-significant. However, a significant negative trend of the rainfall was observed in Ribeirão do Feijão station with a reduction of -10.03 mm year-1. Variabilidade e tendência da temperatura do ar e precipitação na Bacia Hidrográfica do Ribeirão do Lobo, Brasil R E S U M OAs mudanças climáticas têm sido observadas em todo o mundo e são apontadas como responsáveis por impactar os recursos naturais, especialmente a quantidade e a qualidade da água em uma bacia hidrográfica. Assim, o presente trabalho teve como objetivo analisar a variabilidade e as tendências da temperatura do ar e da chuva na Bacia Hidrográfica do Ribeirão do Lobo, Estado de São Paulo, Brasil. Os dados meteorológicos de 1988 a 2017 foram coletados no Centro de Recursos Hídricos e Estudos Ambientais da Universidade de São Paulo (CRHEA), e em cinco estações pluviométricas da Agência Nacional de Águas do Brasil (ANA) distribuídas por toda a bacia. Para identificar as mudanças climáticas, foram aplicados os testes de regressão simples, teste de run, Mann-Kendall e Mann-Kendall modificado. Os resultados mostraram tendências positivas significativas na temperatura do ar, especialmente no período anual e durante o terceiro trimestre, com aumento de até 0,068 °C por ano. Aumentos significativos foram verificados para temperatura mínima, máxima e média do ar, o que sugere possíveis mudanças climáticas no período analisado. Para os dados de chuva, foram encontrados períodos com tendências positivas e negativas, contudo, na maioria das vezes, as tendências não foram significativas. No entanto, uma tendência negativa significativa da precipitação foi observada na estação de Ribeirão do Feijão com redução de -10,03 mm ao ano.Palavras-chave: mudanças climáticas, regressão simples, Mann-Kendall, tendência.

Climatic trends of temperatures and precipitation in Brazilian localities

In recent decades, scientific and academic researchers around the world have been concerned with the assessment of regional and global climate trends. Under the hypothesis of the presence of climate change in Brazil, the aim of this work was to verify annual climate trends of maximum and minimum air temperatures and precipitation in 243 localities over all the Brazilian political regions. The data were obtained from National Institute of Meteorology. In this work there were identified and analysed trends in annual time series distributed between in 1961 and 2017. The detections and analyses were performed by the application of the statistical tests of Mann-Kendall and the Pettitt to evaluate the presence of statistical trends. The statistical results and the trend distributions maps show that, from all the studied localities, for maximum temperature indicate increasing trends in 35% of the series, decreasing trends in 1 and no trends in 64%. The minimum temperature showed increasing trends in 30% of the analysed series, decreasing in 8% and no trends in 63%. The precipitation, showed increasing trends in 6% of the studied series, decreasing in 4 and no trends in 91%. The observed climate trends can be related to anthropological activities like urban spraw, industrial development and increasing population density.

Changing Probabilities of Days with Snow and Rain in the Atlantic Sector of the Arctic under the Current Warming Trend

AbstractTrends in the probabilities of days with liquid, solid, and mixed precipitation are discussed on annual and intra-annual scales along with their relationship to air temperature in the Atlantic sector of the Arctic. Data on weather phenomena were used to identify precipitation phases. The data cover various periods but all series extend to 2017. Trends in the annual air temperature and probability of precipitation phases for various long-term periods are discussed and differences in the mean air temperature and probability of precipitation phases between 1979–97 (insignificant warming) and 1999–2017 (significant warming) on an intra-annual scale. In the studied region, the precipitation phases were sensitive to warming and atmospheric circulation to various degrees, depending on the phase, mean climate, month, and local conditions. The probability of days with rainfall increased (by +1% to +3% per decade), whereas the probability of days with snowfall decreased (by −1.5% to −2.4% per decade). The increasing trends in the probability of rainy days at all stations and decreasing trends in the probability of snowy days in the southern part of the region were warming induced. The most significant and widespread trends in snowy and rainy days were found in September. The probability of days with mixed precipitation exhibited no trends due to an inverse reaction to warming in the warmer and colder parts of the year. Temporal variability in the probability of precipitation phases was significantly linked to three teleconnection patterns playing a role in various parts of the year.

Trend Analyses of Meteorological Variables and Lake Levels for Two Shallow Lakes in Central Turkey

Trend analyses of meteorological variables play an important role in assessing the long-term changes in water levels for sustainable management of shallow lakes that are extremely vulnerable to climatic variations. Lake Mogan and Lake Eymir are shallow lakes offering aesthetic, recreational, and ecological resources. Trend analyses of monthly water levels and meteorological variables affecting lake levels were done by the Mann-Kendall (MK), Modified Mann-Kendall (MMK), Sen Trend (ST), and Linear trend (LT) methods. Trend analyses of monthly lake levels for both lakes revealed an increasing trend with the Mann-Kendall, Linear, and Sen Trend tests. The Modified Mann-Kendall test results were statistically significant with an increasing trend for Eymir lake levels, but they were insignificant for Mogan lake due to the presence of autocorrelation. While trend analyses of meteorological variables by Sen Test were significant at all tested variables and confidence levels, Mann-Kendall, Modified Mann-Kendall, and Linear trend provided significant trends for only humidity and wind speed. The trend analyses of Sen Test gave increasing trends for temperature, wind speed, cloud cover, and precipitation; and decreasing trends for humidity, sunshine duration, and pan evaporation. These results show that increasing precipitation and decreasing pan evaporation resulted in increasing lake levels. The results further demonstrated an inverse relationship between the trends of air temperature and pan evaporation, pointing to an apparent “Evaporation Paradox”, also observed in other locations. However, the increased cloud cover happens to offset the effects of increased temperature and decreased humidity on pan evaporation. Thus, all relevant factors affecting pan evaporation should be considered to explain seemingly paradoxical observations.

The impacts of climate change based on regional and global climate models (RCMs and GCMs) projections (case study: Ilam province)

The climate change is one of the most important challenges facing the environment. In this study, climate change by air temperature and precipitation parameters is evaluated and compared for observational and future data. For the baseline period (1981–2016) and for future (2020–2080) detemined. To estimate future data, utilized the CNRM-CM5 and HadGEM2-ES models output the global climate models (GCMs) from the MarksimGCM database and the CNRM-CERFACS and MIROC-ESM models as regional climate models (RCMs) from the CORDEX project for the domain of south Asia is based on the representation concentration pathway RCP8.5 and RCP4.5 scenarios were considered. The results showed that is an increasing and decreasing trend for air temperature and precipitation in the baseline period, respectively. The validation of the models showed that the CNRM-CM5 model as a GCM model and the CNRM-CERFACS model as an RCM model have a higher performance in simulating climate change for study area. In fact, output of these models have close relation to the observed data. Evaluation of the temperature components (minimum and maximum temperatures) showed these components had an increasing trend in the baseline period and would have an upward deviation in the future. With respect to the changes in air temperature, precipitation and reference evapotranspiration (Eto) for the future, the status of water resources in the study area will decline significantly. Therefore, the effects of climate change are significant for the study area, which need to consider adaptive strategies such as; optimal water management, cropping pattern and resource management.

KONYA KAPALI HAVZASI (TÜRKİYE) YILLIK SICAKLIK VERİLERİNİN TREND ANALİZİ VE DEĞİŞİM NOKTALARININ BELİRLENMESİ

Climate change is expressed as major changes in the average climate which exist for many years. Although climate change occurs on a global scale, the impact of climate change varies from region to region. Therefore, the analysis of the variations in meteorological variables is a very vital issue in monitoring of climate change. In this study, assignment of the change points and trends of annual mean temperature, maximum temperature and minimum temperature data of the Konya Closed Basin in Turkey is examined. For this aim, air temperature data of 11 meteorology station were used. The change point of temperature time series data was examined using the Pettitt test, Standard Normal Homogeneity test and Buishand Range test. The Mann-Kendall, Spearman Rho and Innovative Şen Trend methods were used to determine trends of air temperature.

Trends and correlations in recent air temperature and precipitation observations across Japan (1906–2005)

Air temperature and precipitation data observed and recorded by the Japan Meteorological Agency (JMA) from 1906 to 2005 were analyzed. Observed trends and correlations at 16 weather stations in urban and rural areas over Japan from Nemuro in the north (43.3oN) to Ishigaki in the south (24.3 N) were identified and quantified. Average annual values were emphasized in a previous analysis (Higashino and Stefan 2014). Herein monthly values and extreme events at the daily and hourly timescale were extracted and interpreted. As shown in 2014, observed air temperature rises are much larger in urban than in rural areas and are statistically significant at all sites. Air temperature rises in Japan in the period 1906–2005 are strongest in spring (March, April, and May) and weakest in midsummer (July and August). Monthly air temperature rises have accelerated over time by a factor of about 3 from the period (1906–2005) to (1981–2005), except for a short period in August. In the period (1906–2005), daily minimum air temperature rises have occurred at all sites. Daily and yearly minimum air temperature trends are more than twice as strong as daily and yearly maximum temperature trends. The numbers of annual hot days and hot nights have also increased at most of the study sites in the period (1906–2005), but only the number of hot nights and the daily minimum air temperature are strongly correlated with annual average air temperature increases. The trends in the annual numbers of frost days and hot nights are well correlated with the annual average air temperature trend, one negative, the other positive, as to be expected. Trends in mean annual precipitation are very small, near zero for (1906–2005), mostly negative for 1956–2005, and mostly positive for 1981–2005. There is no correlation with trends in air temperature. Daily maximum precipitation for (1906–2005) and (1956–2005) shows only small and often non-statistically significant changes at the 16 study sites. In (1981–2005), trends have increased significantly but fluctuate significantly between positive and negative trends.

Spatial Patterns and Trends in Surface Air Temperatures and Implied Changes in Atmospheric Moisture Across the Hawaiian Islands, 1905–2017

AbstractWhile the Hawaiian Islands are experiencing long‐term warming, spatial and temporal patterns are poorly characterized. Drawing on daily temperature records from 309 stations (1905–2017), we explored relationships of surface air temperatures (Tmax, Tmin, Tavg, and diurnal temperature range) to atmospheric, oceanic, and land surface variables. Statistical modeling of spatial patterns (2006–2017) highlighted the strong negative influence of elevation and moisture on air temperature and the effects of distance inland, cloud frequency, wind speed, and the local trade wind inversion on the elevation dependence of surface air temperature. We developed time series of sea level air temperature and surface lapse rate by modeling surface air temperature as a simple function of elevation and found a strong long‐term (1905–2017) warming trend in sea level Tmin, twice that of Tmax (+0.17 vs +0.07°C/decade), suggesting regional warming, possibly enhanced by urbanization and cloud cover effects. Removing this trend, sea level Tmax and Tmin tracked SST and rainfall at decadal time scales, while Tmax increased with periods of weakened trade winds. Sea level air temperatures correlated with North Pacific climate indices, reflecting the influence of regional circulation via SST, rain, clouds, and trade winds that modulate environmental warming across the Hawaiian Islands. Increasing (steeper) Tmax surface lapse rates for the 0‐ to 1,600‐m elevation range (into the cloud zone) over 1978–2017 coincide with observations of marine boundary layer drying and rising cloud base heights, suggesting a need to better understand elevation‐dependent warming in this tropical/subtropical maritime environment and associated changes to cloud formation and persistence.

Regional Response to Global Warming: Water Temperature Trends in Semi-Natural Mountain River Systems

River water temperature (TW) is a key environmental factor that determines the quality of the fluvial environment and its suitability for aquatic organisms. Atmospheric warming, accompanied by more frequent extreme weather phenomena, especially heat waves and prolonged drought, may pose a serious threat to the river environment and native river ecosystems. Therefore, reliable and up-to-date information on current and anticipated changes in river flow and thermal conditions is necessary for adaptive water resource management and planning. This study focuses on semi-natural mountain river systems to reliably assess the magnitude of water temperature change in the Polish Carpathians in response to climatic warming. The Mann–Kendall test was used to detect trends in water temperature series covering the last 35 years (1984–2018). Significant, rising trends in annual water temperature were found for all studied sites, with differences in intensity (0.33–0.92 °C per decade). Trends in TW were strongest in summer and autumn (0.75–1.17 and 0.51–1.08 °C per decade), strong trends were found in spring (0.82–0.95 °C per decade), and weaker in winter (0.25–0.29 °C per decade). Simultaneous air temperature trends were broadly consistent with water temperature trends. This indicates the urgent need for adaptive management strategies to counteract thermal degradation of the fluvial environment under study.