Warm Spells Research Articles

Let it snow! Winter conditions affect growth of birch seedlings during the following growing season.

Air temperatures and precipitation are predicted to increase in the future, especially at high latitudes and particularly so during winter. In contrast to air temperatures, changes in soil temperatures are more difficult to predict, as the fate of the insulating snow cover is crucial in this respect. Soil conditions can also be affected by rain-on-snow events and warm spells during winter, resulting in freeze-thaw cycles, compacted snow, ice encasement and local flooding. These adverse conditions during winter could counteract the otherwise positive effects of climate change on forest growth and productivity. For studying the effects of different winter and snow conditions on young Downy birch (Betula pubescens Ehrh.) seedlings, we carried out a laboratory experiment with birch seedlings subjected to four different winter scenarios: snow covering the seedlings (SNOW), compressed snow and ice encasement (ICE), flooded and frozen soil (FLOOD) and no snow at all (NO SNOW). After the winter treatments we simulated a spring and early summer period of 9.5 weeks, and monitored the growth by measuring shoot and root biomass of the seedlings, and starch and soluble sugar concentrations. We also assessed the stress experienced by the seedlings by measuring leaf chlorophyll fluorescence and gas exchange. Although no difference in mortality was observed between the treatments, the seedlings in the SNOW and ICE treatments had significantly higher shoot and root biomass compared with those in the FLOOD and NO SNOW treatments. We found higher starch concentrations in roots of the seedlings in the SNOW and ICE treatments, compared with those in the FLOOD and NO SNOW treatments, although photosynthesis did not differ. Our results suggest a malfunction of carbohydrate distribution in the seedlings of the FLOOD and NO SNOW treatments, probably resulting from decreased sinks. The results underline the importance of an insulating and protecting snow cover for small tree seedlings, and that future winters with changed snow pattern might affect the growth of tree seedlings and thus possibly species composition and forest productivity.

Extreme Temperature Events and Rice Production in Bangladesh

The extreme climatic events are increasing because of climate change impacts and thus likely to influence global agricultural production. Regional assessments on various abiotic factors and its influences on biological entities in diverse geographic locations are needed for understanding uncertainties. Rice grain yields and daily temperature data from 1971–2015 were used to quantify extreme temperature events in different regions of Bangladesh and their impacts on rice yields growing in three seasons of Bangladesh. The regional averaged trends in temperature extremes were consistent with global warming. The occurrence summer days (SU), tropical nights (TR), warm days (TX90), and nights (TN90) and a warm spell duration indicator (WSDI) increased by 0.388 (P0.00001), 0.103 (P0.19), 0.520 (P0.00000), 0.269 (P0.0004), 0.147 (P0.0001), days yr-1, respectively. The frequencies of cold days (TX10) and nights (TN10), and cold spell duration indicator (CSDI) showed decreasing trends of −0.143 (P0.0006), −0.254 (P0.001), and −0.04 (P0.227) day yr-1, respectively. Sharp increases of TR and TN90 indices took place in 1985–2000. Principal component analysis showed that SU, TX90, TN90, WSDI, TX10, TN10 and diurnal temperature range (DTR) were the main influencing factors for seasonal variations in rice yield. Warm and cold nights played a vital role in reducing rice yields. It can be concluded that extreme temperature events will be increased in Bangladesh and thus necessitating heat and cold tolerant rice varieties with appropriate management options for sustained future rice production in Bangladesh.

Valuing the diverse economies and climate possibilities of a winter festival in Western Maine, USA

A group of citizens in western Maine was recently galvanized by their shared, volunteer labor of preparing a course for a major regional ski race during a low snow season. Working late into the night they shoveled snow by hand from the woods to the race course, paving the way for the success of the event, as well as animating subsequent efforts to use winter sports to build a diverse economy. Shortly after rescuing the race from a warm spell, the citizens group successfully planned and hosted a larger regional ski festival. Their follow-up festival incorporated an experiment in a walkable/skiable event venue with shuttle buses providing transportation to lodging and off-site parking for day trippers. In keeping with the diverse economies framework (Gibson-Graham 2006, 2008), festival organizers worked with researchers to estimate the value of their own volunteer labor, in addition to measuring the emitted and avoided CO2 resulting from their mitigation practices. This paper shares the results of the festival study while documenting how a particular instance of community labor bridges different interests, performs diverse economies and enacts a “climate politics of hope” in the face of climate uncertainty.

Spatio-Temporal Trend Analysis of Rainfall and Temperature Extremes in the Vea Catchment, Ghana

This study examined the trends in annual rainfall and temperature extremes over the Vea catchment for the period 1985–2016, using quality-controlled stations and a high resolution (5 km) Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) data. The CHIRPS gridded precipitation data’s ability in reproducing the climatology of the catchment was evaluated. The extreme rainfall and temperature indices were computed using a RClimdex package by considering seventeen (17) climate change indices from the Expert Team on Climate Change Detection Monitoring Indices (ETCCDMI). Trend detection and quantification in the rainfall (frequency and intensity) and temperature extreme indices were analyzed using the non-parametric Mann–Kendall (MK) test and Sen’s slope estimator. The results show a very high seasonal correlation coefficient (r = 0.99), Nash–Sutcliff efficiency (0.98) and percentage bias (4.4% and −8.1%) between the stations and the gridded data. An investigation of dry and wet years using Standardized Anomaly Index shows 45.5% frequency of drier than normal periods compared to 54.5% wetter than normal periods in the catchment with 1999 and 2003 been extremely wet years while the year 1990 and 2013 were extremely dry. The intensity and magnitude of extreme rainfall indices show a decreasing trend for more than 78% of the rainfall locations while positive trends were observed in the frequency of extreme rainfall indices (R10mm, R20mm, and CDD) with the exception of consecutive wet days (CWD) that shows a decreasing trend. A general warming trend over the catchment was observed through the increase in the annual number of warm days (TX90p), warm nights (TN90p) and warm spells (WSDI). The spatial distribution analysis shows a high frequency and intensity of extremes rainfall indices in the south of the catchment compared to the middle and northern of part of the catchment, while temperature extremes were uniformly distributed over the catchment.

Evaporation from (Blue-)Green Roofs: Assessing the Benefits of a Storage and Capillary Irrigation System Based on Measurements and Modeling

Worldwide cities are facing increasing temperatures due to climate change and increasing urban density. Green roofs are promoted as a climate adaptation measure to lower air temperatures and improve comfort in urban areas, especially during intensive dry and warm spells. However, there is much debate on the effectiveness of this measure, because of a lack of fundamental knowledge about evaporation from different green roof systems. In this study, we investigate the water and energy balance of different roof types on a rooftop in Amsterdam, the Netherlands. Based on lysimeter measurements and modeling, we compared the water and energy balance of a conventional green roof with blue-green roofs equipped with a novel storage and capillary irrigation system. The roofs were covered either with Sedum or by grasses and herbs. Our measurements and modeling showed that conventional green roof systems (i.e., a Sedum cover and a few centimeters of substrate) have a low evaporation rate and due to a rapid decline in available moisture, a minor cooling effect. Roofs equipped with a storage and capillary irrigation system showed a remarkably large evaporation rate for Sedum species behaving as C3 plants during hot, dry periods. Covered with grasses and herbs, the evaporation rate was even larger. Precipitation storage and capillary irrigation strongly reduced the number of days with dry-out events. Implementing these systems therefore could lead to better cooling efficiencies in cities.

Spatiotemporal Variability and Trends in Extreme Temperature Events in Finland over the Recent Decades: Influence of Northern Hemisphere Teleconnection Patterns

Fifteen temperature indices recommended by the ETCCDI (Expert Team on Climate Change Detection and Indices) were applied to evaluate spatiotemporal variability and trends in annual intensity, frequency, and duration of extreme temperature statistics in Finland during 1961–2011. Statistically significant relationships between these high-resolution (10 km) temperature indices and seven influential Northern Hemisphere teleconnection patterns (NHTPs) for the interannual climate variability were also identified. During the study period (1961–2011), warming trends in extreme temperatures were generally manifested by statistically significant increases in cold temperature extremes rather than in the warm temperature extremes. As expected, warm days and nights became more frequent, while fewer cold days and nights occurred. The frequency of frost and icing days also decreased. Finland experienced more (less) frequent warm (cold) temperature extremes over the past few decades. Interestingly, significant lengthening in cold spells was observed over the upper part of northern Finland, while no clear changes are found in warm spells. Interannual variations in the temperature indices were significantly associated with a number of NHTPs. In general, warm temperature extremes show significant correlations with the East Atlantic and the Scandinavia patterns and cold temperature extremes with the Arctic Oscillation and the North Atlantic Oscillation patterns.

Overwintering Behavior of Drosophila suzukii, and Potential Springtime Diets for Egg Maturation.

Spotted wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), is a serious agricultural pest, which lays eggs in ripe and ripening fruits of several cultivated and wild host plants. Here we explore several factors that may be critical to winter survival and improve D. suzukii's ability to successfully overwinter in northern climates and reestablish populations in the spring. Cold acclimation improved mobility in low-temperature laboratory mobility assays and improved survivorship in two wintertime field studies. Acclimation improved survivorship in experiments where overwintering habitats were above ground level and where habitats were at soil level by 1.9- and 13.7-fold, respectively. Soil acts to buffer changes in temperature, and the groundcovers investigated here provided microclimates that were 1-2°C warmer than bare soil during chilling events, and roughly 5°C cooler than bare soil during warm spells. Acclimated flies preferred overwintering substrates with a food source (dropped apple) over any other substrate (leaf litter, barky sticks, or bare soil). Pigeon (Columba livia L.) droppings and mushrooms (Peziza sp.) were identified as potential overwintering protein sources in laboratory feeding studies. Laboratory-simulated winter stress negatively influenced return of female reproduction, so future assays should consider biologically relevant subjects.

Changes in temperature and precipitation extremes in Ethiopia, Kenya, and Tanzania

East Africa is one of the most vulnerable regions of Africa to extreme weather and climate events. Regional and local information on climate extremes is critical for monitoring and managing the impacts and developing sustainable adaptation measures. However, this type of information is not readily available at the necessary spatial resolution. Therefore, here we test trends and variability of temperature (1979–2010) and precipitation (1981–2016) extremes in East Africa, particularly Ethiopia, Kenya, and Tanzania, at a spatial resolution of 0.1 and 0.05°, respectively, using the indices defined by the Expert Team on Climate Change Detection and Indices (ETCCDI). We use gridded data sets with high accuracy and resolution from the Terrestrial Hydrology Research Group, University of Princeton and Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS). Trends of 19 indices are computed by fitting a linear model and using the nonparametric Mann–Kendall test and the magnitude of change is computed using the Sen's slope method. The results show an increasing trend in monthly maximum and minimum values of daily maximum and minimum temperature in large parts of the region. This is accompanied by significant increasing trends in warm nights (TN90p), warm days (TX90p), warm spell duration index (WSDI), and summer days index (SU). In addition, cold days (TX10p) and cold nights (TN10p) showed a significant decreasing trend. In general, the results show an increasing tendency in temperatures extremes, which is in line with rising global mean temperature. In addition, most of the temperature extremes observed after 2000 are warmer than the long‐term mean (1979–2010). Precipitation indices, on the other hand, showed increasing and decreasing trends in Ethiopia, Kenya, and Tanzania, but no general pattern. The outcomes enable identifying hot spot areas and planning of adaptation and mitigation measures at much finer spatial scale than previously possible.

Vector competence of pre-alpine Culicoides (Diptera: Ceratopogonidae) for bluetongue virus serotypes 1, 4 and 8

BackgroundBluetongue disease, caused by bluetongue virus serotype 8 (BTV-8), appeared for the first time in the northern part of Europe in 2006, and subsequently rapidly spread causing severe economic losses to the farming industry. The implicated vectors of BTV in Europe are Culicoides species within the subgenus Avaritia (C. chiopterus, C. dewulfi, C. obsoletus and C. scoticus). Epidemiological data from Switzerland have shown that BTV, whose spread was eliminated at an early stage by vaccination campaigns, had not been circulating among livestock at higher altitudes where other species dominate the Culicoides fauna. In this study, we investigated the extent that Culicoides spp. prevailing at higher altitudes (mainly C. grisescens) can act as vectors for BTV.MethodsCulicoides were collected at farms in the pre-alpine region (two sites at 1550 m above sea level, masl, referred to as pre-alpine I; one site at 2030 masl, pre-alpine II) and, for comparative purposes, from the Swiss Plateau (one site, 650 masl). They were fed on bovine blood/BTV suspensions (BTV-1, 4 or 8) and incubated for eight days under a fluctuating temperature regime (13–25 °C, mean 19 °C), reflecting a mid-summer warm spell in the pre-alpine region. Susceptibility to BTV transmission was assessed from head homogenates by RT-qPCR and virus isolation.ResultsOverall, 9196 female Culicoides were exposed to the three BTV strains through an artificial membrane, with feeding rates of 14–27%. Survival rates of blood-engorged Culicoides females at eight days post-infection depended on both virus serotype and altitude of origin. Virus dissemination (Cq ≤ the cut-off value as determined by serial virus dilutions) was confirmed only for BTV-1 in C. scoticus (dissemination efficiency 22.5%; 9/40) and C. obsoletus (5.6%; 1/18) from the Swiss Plateau area. There was no strong evidence of susceptibility to infection for Culicoides from the pre-alpine area when fed with all BTV strains (BTV-1, 4 and 8).ConclusionsThis study confirms the susceptibility of C. scoticus and C. obsoletus to BTV-1 infection, including under cooler temperatures. Culicoides grisescens, which is highly abundant at higher altitudes, cannot be considered a potential vector under these temperature conditions.

Storm impacts on alpine lakes: Antecedent weather conditions matter more than the event intensity.

Extreme weather events may be just as important as gradual trends for the long-term trajectories of ecosystems. For alpine lakes, which are exposed to both exacerbated atmospheric warming and intense episodic weather events, future conditions might not be appropriately forecast by only climate change trends, i.e. warming, if extreme events have the potential to deflect their thermal and metabolic states from their seasonal ranges. We used high-frequency monitoring data over three open-water seasons with a one-dimensional hydrodynamic model of the high-altitude Lake Muzelle (France) to show that rainstorms or windstorms, notwithstanding their intensity, did not trigger long-lasting consequences to the lake characteristics when light penetration into the lake was not modified. In contrast, storms associated with high turbidity input from the watershed ("turbid storms") strongly modified the lacustrine hydrodynamics and metabolism for the rest of the open-water season through reduced light penetration. The long-lasting effects of turbid storms were related to the inputs and in-lake persistence of very light glacial suspensoids from the watershed. The occurrence of the observed turbid storms was not related to the wind or rain intensities during the events. Instead, the turbid storms occurred after dry and atypically warm spells, i.e. meteorological conditions expected to be more frequent in this alpine region in the upcoming decades. Consequently, storm events, notwithstanding their intensity, are expected to strongly imprint the future ecological status of alpine lakes under climate warming.

Extreme temperature and precipitation response to solar dimming and stratospheric aerosol geoengineering

Abstract. We examine extreme temperature and precipitation under two potential geoengineering methods forming part of the Geoengineering Model Intercomparison Project (GeoMIP). The solar dimming experiment G1 is designed to completely offset the global mean radiative forcing due to a CO2-quadrupling experiment (abrupt4 × CO2), while in GeoMIP experiment G4, the radiative forcing due to the representative concentration pathway 4.5 (RCP4.5) scenario is partly offset by a simulated layer of aerosols in the stratosphere. Both G1 and G4 geoengineering simulations lead to lower minimum temperatures (TNn) at higher latitudes and on land, primarily through feedback effects involving high-latitude processes such as snow cover, sea ice and soil moisture. There is larger cooling of TNn and maximum temperatures (TXx) over land compared with oceans, and the land–sea cooling contrast is larger for TXx than TNn. Maximum 5-day precipitation (Rx5day) increases over subtropical oceans, whereas warm spells (WSDI) decrease markedly in the tropics, and the number of consecutive dry days (CDDs) decreases in most deserts. The precipitation during the tropical cyclone (hurricane) seasons becomes less intense, whilst the remainder of the year becomes wetter. Stratospheric aerosol injection is more effective than solar dimming in moderating extreme precipitation (and flooding). Despite the magnitude of the radiative forcing applied in G1 being ∼ 7.7 times larger than in G4 and despite differences in the aerosol chemistry and transport schemes amongst the models, the two types of geoengineering show similar spatial patterns in normalized differences in extreme temperatures changes. Large differences mainly occur at northern high latitudes, where stratospheric aerosol injection more effectively reduces TNn and TXx. While the pattern of normalized differences in extreme precipitation is more complex than that of extreme temperatures, generally stratospheric aerosol injection is more effective in reducing tropical Rx5day, while solar dimming is more effective over extra-tropical regions.

Multimodel detection and attribution of changes in warm and cold spell durations

The duration of warm and cold spells is measured by the persistence of instances when daily temperatures are greatly above or below their normal values. These spells represent a prolonged period of times when daily temperatures are extreme and can potentially be connected to climate impacts in the agricultural, health, energy and other sectors. This study aims to determine evidence of responses in the durations of warm (WSDI) and cold (CSDI) spells to forcings external to the climate system. We consider the globe, the six continents and China during the period from 1958−2010 in this analysis. Here we compare the observed duration indices with those derived from simulated daily temperature by climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5), using an optimal fingerprint method. The results show that, averaged over the global lands, the WSDI has substantially increased by 15 days while the CSDI has decreased by 3 days over the 53 year period. The simulated changes are generally consistent with the observations; models, however, overestimate the observed changes in the WSDI in five of the six continental regions. We consider a signal is detected if it is significant at the 10% level. At the global scale, human influences on both warm and cold spell durations are detected. At the continental scale, an anthropogenic signal is detected in the warm spell durations of most continents. The human influence on cold spell duration is detectable only in the Asian and European continents. In China, human influence can clearly be detected in both the warm and cold spell durations. Responses to natural forcings are generally not detected at the continental or smaller spatial scales.

Temperature extremes in Alaska: temporal variability and circulation background

The aims of this study are to characterize the spatial and temporal variability of extremely warm days (WDs) and warm spells (WSs) in summer as well as extremely cold days (CDs) and cold spells (CSs) in winter in Alaska in the years 1951–2015 and to determine the role of atmospheric circulation in their occurrence. The analysis is performed using daily temperature maxima (TMAX) and minima (TMIN) measured at 10 weather stations in Alaska as well as mean daily values of sea level pressure and wind direction at the 850 hPa isobaric level.WD (CD) is defined as a day with TMAX above the 95th (TMIN below the 5th) percentile of a probability density function calculated from observations, and WS (CS) equals at least three consecutive WDs (CDs). Frequency of the occurrence and severity of warm and cold extremes as well as duration of WSs and CSs is analyzed. In order to characterize synoptic conditions during temperature extremes, the objective classification scheme of advection types considering jointly the direction of the air influx and type of pressure system is employed.The results show that the general trend is towards the warmer temperatures, and the warming is greater in the winter than summer and for TMAX as opposed to TMIN. This is reflected in changes in the frequency of occurrence and intensity of temperature extremes which are much more pronounced in the case of winter cold extremes (decreasing tendencies) than summer warm extremes (increasing tendencies).The occurrence of temperature extremes is generally favored by anticyclonic weather with advection direction indicating air mass flows from the interior of the North American continent as well as the south (warm extremes in summer) and north (cold extremes in winter).

The Legacy Effects of Winter Climate on Microbial Functioning After Snowmelt in a Subarctic Tundra

Warming-induced increases in microbial CO2 release in northern tundra may positively feedback to climate change. However, shifts in microbial extracellular enzyme activities (EEAs) may alter the impacts of warming over the longer term. We investigated the in situ effects of 3years of winter warming in combination with the in vitro effects of a rapid warming (6days) on microbial CO2 release and EEAs in a subarctic tundra heath after snowmelt in spring. Winter warming did not change microbial CO2 release at ambient (10°C) or at rapidly increased temperatures, i.e., a warm spell (18°C) but induced changes (P < 0.1) in the Q10 of microbial respiration and an oxidative EEA. Thus, although warmer winters may induce legacy effects in microbial temperature acclimation, we found no evidence for changes in potential carbon mineralization after spring thaw.

Temperature and precipitation extremes under current, 1.5 °C and 2.0 °C global warming above pre-industrial levels over Botswana, and implications for climate change vulnerability

Climate extremes are widely projected to become more severe as the global climate continues to warm due to anthropogenic greenhouse gas emissions. These extremes often cause the most severe impacts on society. Therefore, the extent to which the extremes might change at regional level as the global climate warms from current levels to proposed policy targets of 1.5 and 2.0 °C above preindustrial levels need to be understood to allow for better preparedness and informed policy formulation. This paper analysed projected changes in temperature and precipitation extremes at 1.0, 1.5 and 2.0 °C warming over Botswana, a country highly vulnerable to the impacts of climate change. Projected changes in temperature extremes are significantly different from each other at the three levels of global warming, across three main climatic zones in the country. Specifically, at 2.0 °C global warming relative to preindustrial, for the ensemble median: (a) country average warm spell duration index increases by 80, 65, 62 days per year across different climatic zones, approximately three (and two) times the change at 1.0 (1.5) °C; (b) cold night (TN10P) and cold day (TX10P) frequencies decrease by 12 and 9 days per year across all regions, respectively, while hot nights (TN90P) and hot days (TX90P) both increase by 8–9 days across all regions. Projected changes in drought-related indices are also distinct at different warming levels. Specifically: (a) projected mean annual precipitation decreases across the country by 5%–12% at 2 °C, 3%–8% at 1.5 °C and 2%–7% at 1.0 °C; (b) dry spell length (ALTCDD) increases by 15–19 days across the three climatic zones at 2.0 °C, about three (and two) times as much as the increase at 1.0 (1.5) °C. Ensemble mean projections indicate increases in heavy rainfall indices, but the inter-model spread is large, with no consistent direction of change, and so changes are not statistically significant. The implications of these changes in extreme temperature and precipitation for key socio-economic sectors are explored, and reveal progressively severe impacts, and consequent adaptation challenges for Botswana as the global climate warms from its present temperature of 1.0 °C above preindustrial levels to 1.5 °C, and then 2.0 °C.

Comparison of regional and seasonal changes and trends in daily surface temperature extremes over India and its subregions

Regional changes in surface meteorological variables are one of the key issues affecting the Indian subcontinent especially in recent decades. These changes impact agriculture, health, water, etc., hence important to assess and investigate these changes. The Indian subcontinent is characterized by heterogeneous temperature regimes at regional and seasonal scales. The India Meteorological Department (IMD) observations are limited to recent decades as far as its spatial distribution is concerned. In particular, over Hilly region, these observations are sporadic. Due to variable topography and heterogeneous land use/land cover, it is complex to substantiate impacts. The European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim (ERA-I) reanalysis not only covers a larger spatial domain but also provides a greater number of inputs than IMD. This study used ERA-I in conjunction with IMD gridded data to provide a comparative assessment of changing temperature patterns over India and its subregions at both regional and seasonal scales. Warming patterns are observed in both ERA-I and IMD data sets. Cold nights decrease during winter; warm days increase and warm spell duration increased during winter could become a cause of concern for society, agriculture, socio-economic reasons, and health. Increasing warm days over the hilly regions may affect the corresponding snow cover and thus river hydrology and glaciological dynamics. Such changes during monsoon are slower, which could be attributed to moisture availability to dampen the temperature changes. On investigation and comparison thereon, the present study provisions usages of ERA-I-based indices for various impact and adaptation studies.

Climate Extremes and Their Impacts on Interannual Vegetation Variabilities: A Case Study in Hubei Province of Central China

As the frequency and intensity of climate extremes are likely to be substantially modified in upcoming decades due to climate warming, an evaluation of the response of interannual vegetation variabilities to climate extremes is imperative. This study comprehensively analyzed the spatio-temporal variabilities of 21 temperature and precipitation indices across Hubei Province in Central China based on daily meteorological records for the period 1961–2015. To quantify the sensitivity of the vegetation to climate indices in the study area, we correlated climate indices with three vegetation indicators: leaf area index, normalized difference vegetation index, and gross primary productivity. The results indicated that warm-related indices exerted considerable increasing trends, especially for summer days at a rate of 0.35 days year−1 (p &lt; 0.01). In addition, the trends of 18 indices during 1982–2015 were larger than those during 1961–2015, indicating accelerated climate changes in Hubei Province. Spatially, extreme precipitation showed increases in the eastern regions of the study area and decreases in the western regions. Correlation analyses revealed that warm anomalies of the Atlantic Multidecadal Oscillation resulted in extreme warm conditions and extreme precipitation in the study area. Stepwise linear regression analyses identified three temperature indices and three precipitation indices, which were mostly correlated with the three ecosystem variables at the site scale. Further multiple regressions demonstrated the main negative impacts caused by frost days, warm spell duration, extremely heavy precipitation, and consecutive dry days on the terrestrial ecosystem in Hubei Province. Our study provides an improved understanding of the effects of climate extremes on terrestrial ecosystems and can also offer a basis for the management of mitigating damage from climate extremes.

Future Caribbean Climates in a World of Rising Temperatures: The 1.5 vs 2.0 Dilemma

A 10-member ensemble from phase 5 of the Coupled Model Intercomparison Project (CMIP5) is used to analyze the Caribbean’s future climate when mean global surface air temperatures are 1.5°, 2.0°, and 2.5°C above preindustrial (1861–1900) values. The global warming targets are attained by the 2030s, 2050s, and 2070s respectively for RCP4.5. The Caribbean on average exhibits smaller mean surface air temperature increases than the globe, although there are parts of the region that are always warmer than the global warming targets. In comparison to the present (using a 1971–2000 baseline), the Caribbean domain is 0.5° to 1.5°C warmer at the 1.5°C target, 5%–10% wetter except for the northeast and southeast Caribbean, which are drier, and experiences increases in annual warm spells of more than 100 days. At the 2.0°C target, there is additional warming by 0.2°–1.0°C, a further extension of warm spells by up to 70 days, a shift to a predominantly drier region (5%–15% less than present day), and a greater occurrence of droughts. The climate patterns at 2.5°C indicate an intensification of the changes seen at 2.0°C. The shift in the rainfall pattern between 1.5°C (wet) and 2.0°C (dry) for parts of the domain has implications for regional adaptation pursuits. The results provide some justification for the lobby by the Caribbean Community and Small Island Developing States to limit global warming to 1.5°C above preindustrial levels, as embodied in the slogan “1.5 to Stay Alive.”

Recent trends in daily temperature extremes over the central Adriatic region of Italy in a Mediterranean climatic context

ABSTRACTThis study provides an assessment of recent changes in near‐surface air temperature over the central Adriatic region of Italy, focusing on extreme events at annual and seasonal scales. It investigates trends in selected indices calculated from quality controlled and homogenized daily temperature data recorded from 1980 to 2012 at 34 meteorological stations distributed over the territory. The results reveal overall warming tendencies, particularly pronounced in spring and summer, with significant increases in the duration of warm spells (WSDI) and in the frequency of warm days (TX90p) and warm nights (TN90p), summer days (SU) and tropical nights (TR). Moreover, cold‐related extremes (cold spell duration (CSDI), cool days (TX10p) and cool nights (TN10p), frost days (FD) and icing days (ID)) show significant reductions, although of lower magnitudes, thus confirming the recent warming over the study domain. Prevalent increasing tendencies are also observed for absolute extreme temperature indices (highest and lowest daily values of maximum and minimum temperatures), but with more mixed and less uniform spatial patterns. Finally, the influence of large‐scale circulation modes on temperature extremes is examined. The results highlight the presence of significant correlations between most of the selected extreme temperature indices and the East‐Atlantic pattern, in particular for the warm season.

A Comparative Study on Extreme Heat between Guadalquivir Valley and Segura River Valleys: Trend and High Resolution Cartography

The Guadalquivir and Segura Valleys are geographical areas in the south of the Iberian Peninsula where extreme summer temperatures have great recurrence of extremely high values, especially during the last summers. A comparison of the characteristics of extreme heat between the two zones is proposed, analyzing the statistical trend (1900-2017) of the cities of Seville and Murcia and a detailed cartography of the warm poles of maximum and minimum temperatures is provided using high resolution modeling tools (AROME 1.3 km) and remote sensing (MYD11A1). The results are conclusive, since there is a statistically significant increase of the days with extreme heat indices (TX35, TX40 and TN20), while periods of warm spells (WSDI) increase in recurrence and duration.