Regional Climate Variability Research Articles

Future climate change in the Agulhas system and its associated impact on South African rainfall

South African climate variability has been linked to changes in both the Agulhas system and external forcing (i.e. CO2 and ozone). We analysed future climate change in the Agulhas system volume transport and its associated impacts on South Africa’s precipitation using the Community Climate System Model version 4 as part of the Coupled Model Intercomparison Project, phase 5. Output from one historical and three future greenhouse gas emission scenarios were examined to project various climate storylines. We found that the Agulhas Current volume transport decreases across all three scenarios and that the current displays a strong baroclinic component with an increase in transport at the surface and decrease at intermediate depths. Agulhas leakage was found to increase with historical emissions. Additionally, an east-west dipole pattern for convective precipitation was found over South Africa, with an increase over the eastern region related to an increase in greenhouse gas emissions and a decrease in the western region linked to the location of Hadley cell edge latitude. Moving into the 21st century, future predictions in regional climate variability are shown to be dependent on the intensity of greenhouse gas emissions and are extremely important for South Africa, a region prone to drought and flooding and home to a large population dependent on rain-fed agriculture. Significance: Future climate variability in the Agulhas system and South African region is heavily dependent on changes in external forcing. The Agulhas Current volume transport decreases as the greenhouse gas emissions continue to increase and a strong baroclinic component is found with an increase in transport at the surface and a decrease at the intermediate depths. A strong east-west dipole precipitation pattern is found over South Africa with the increase in the eastern region related to the increase in greenhouse gas emissions and the decrease in the western region related to the location of the Hadley cell edge latitude.

Statistical Connections between Large-Scale Climate Indices and Observed Mean and Extreme Temperatures in the US from 1948 to 2018

In order to better understand the extent to which global climate variability is linked to the frequency and intensity of heat waves and overall changes in temperature throughout the United States (US), correlations between long-term monthly mean, minimum, and maximum temperatures throughout the contiguous US on the one hand and low-frequency variability of multiple climate indices (CIs) on the other hand are analyzed for the period from 1948 to 2018. The Pearson’s correlation coefficient is used to assess correlation strength, while leave-one-out cross-validation and a bootstrapping technique (p-value) are used to address potential serial and spurious correlations and assess the significance of each correlation. Three parameters defined the sliding windows over which surface temperature and CI values were averaged: window size, lag time between the temperature and CI windows, and the beginning month of the temperature window. A 60-month sliding window size and 0 lag time resulted in the highest correlations overall; beginning months were optimized on an individual site basis. High (r ≥ 0.60) and significant (p-value ≤ 0.05) correlations were identified. The Western Hemisphere Warm Pool (WHWP) and El Niño/Southern Oscillation (ENSO) exhibited the strongest links to temperatures in the western US, tropical Atlantic sea surface temperatures to temperatures in the central US, the WHWP to temperatures throughout much of the eastern US, and atmospheric patterns over the northern Atlantic to temperatures in the Northeast and Southeast. The final results were compared to results from previous studies focused on precipitation and coastal sea levels. Regional consistency was found regarding links between the northern Atlantic and overall weather and coastal sea levels in the Northeast and Southeast as well as on weather in the upper Midwest. Though the MJO and WHWP revealed dominant links with precipitation and temperature, respectively, throughout the West, ENSO revealed consistent links to sea levels and surface temperatures along the West Coast. These results help to focus future research on specific mechanisms of large-scale climate variability linked to US regional climate variability and prediction potential.

Multi-proxy paleohydrological and paleoecological reconstruction of a subaquatic cave in western Cuba

Submerged caves are potentially rich but relatively untapped sources of paleoenvironmental, paleontological, and archaeological data. The purpose of this study is to undertake a paleohydrological and paleoecological reconstruction of an underwater cave, Cueva Chicharrones, in Matanzas, Cuba. Technical cave divers collected sediment cores from within the cave, which were studied for grain size, seeds, ostracods, and pollen, and were dated by radiocarbon and luminescence methods. The chronology of the sediments and the resulting paleohydrological reconstruction, based on the interpretation of the sedimentary facies, help to constrain the timing of water level changes in the cave, which appear to be driven by a combination of relative sea level and regional climatic variability. Specifically, the results indicate that the cave was likely dry prior to 7000 cal yr BP, and was flooded by 6500 cal yr BP (a time consistent with humid conditions in much of the northern Caribbean). Then, water levels decreased between 6500 and 2000 cal yr BP, when regional climate was drier, and increased around 1000 cal yr BP, due to a shift to a more humid climate. The seeds found in some of the cores consist of the genera Ficus, Cecropia, and Solanum and may have been deposited by frugivorous bats, although the possibility of transport by storm water cannot be ruled out. The pollen data are consistent with the information derived from the seeds, and indicate that pollen spectra variability was probably driven by changes in water level, environmental and climatic conditions, and possibly bat activity. This study is the first of its kind from a submerged cave in Cuba and highlights the potential of underwater caves as archives of regional paleoclimatic and relative sea level data. In addition, given the presence of abundant vertebrate fossils present in the cave, our work will provide important context for the study of these remains and help inform on Caribbean paleoecology and paleontology.

ENSO-driven abrupt phase shift in North Atlantic oscillation in early January

El Niño-Southern Oscillation (ENSO) teleconnections exhibit a strong dependency on seasonally and intraseasonally varying mean states, leading to impactful short-term variations in regional climate. The North Atlantic Oscillation (NAO)-ENSO relation is a typical example, in that its phase relationship reverses systematically between the early and late winter. Here based on observations and an ensemble of atmosphere-only climate model simulations, we reveal that this NAO phase reversal occurs synchronously in early January, showing strong abruptness. We demonstrate that this abrupt NAO phase reversal is caused by the change in ENSO-induced Rossby wave-propagating direction from northeastward to southeastward over the northeastern North American region, which is largely governed by a climatological alteration of the local jet meridional shear. We also provide evidence that the North Atlantic intrinsic eddy–low-frequency flow feedback further amplifies the NAO responses. This ENSO-related abrupt NAO change offers an avenue for intraseasonal climate forecasting in the Euro-Atlantic region.

Deoxygenation and stratification dynamics in a coastal marine lake

Rogoznica Lake (RL; “Zmajevo oko”) is a shallow marine body of water that exhibits the physical characteristics of lakes (layer overturn and morphology), estuaries (distinct halocline), and seas (tidal regime). This study addresses the physicochemical stratification of the RL and its evolution over 27 years since the beginning of continuous RL research, in the context of regional climate variability. Stratification dynamics were evaluated from several aspects. First, reduced sulphur species accumulation was noted, which was associated with the anoxic water expansion from the bottom of the lake. Second, the connection of the lake with the sea and its attenuation was observed. These results are supported by the negative correlation between annual precipitation and water column salinity, which shows that the role of atmospheric variability in controlling the stability of the lake has increased. A change in the surface layer warming rate was noted, possibly related to unresolved quasi-decadal climate variability. At the same time, the enhancement of the chemocline is in favour of the reported stagnation of the bottom layer. All results suggest that there is a positive feedback mechanism leading to rapid ecosystem degradation.

Effect of urbanization on East African climate as simulated by coupled urban-climate model

This study examines the effect of urbanization on climate variability over East Africa. Seasonal trend of rainfall and temperature was analyzed using Mann-Kendall trend test and statistically significant rainfall trend is observed during spring (February-May) and summer (June-September) over northeast and spring/“bega”(October-January) seasons in southeastern regions of Ethiopia, thereby suggesting a seasonal shift of rainfall distribution. The temperature trend showed significant warming in the simulated field, except in central East Sudan, where there has been a significant decline. A numbers of idealized sensitivity experiments have been conducted with the Regional Climate Model (RegCM4.6) to investigate the contribution of urbanization to the East African region climate variability and trend. Model assessment against observed climate variables showed good performance in the simulation of spatial and temporal variability of regional climate variables. The results of the sensitivity experiment by prescribing different urban environments (tall building district (TBD), high density (HD), medium density (MD) and original land use) for the surface scheme (CLM4.5) reveal statistically significant impacts of urbanized surfaces on surface temperatures and precipitation due to variations in energy budget, local circulation and disturbance of hydro meteorological variables. It is noted that TBD urban environment has a higher impact on the local climate than other urban environments. Patterns of seasonal rainfall variability simulated using artificially urbanized land cover suggests involvement of complex interactions and is less similar to the observed rainfall trend, while surface temperature variability is significantly affected by local land-cover change and is very similar to the observed surface temperature trend.

Barotropic and Nonlinear Decay of the Wintertime Baroclinic Wave Packets over the North Pacific: Energetics Analysis

Abstract Based on daily data from the Japanese 55-year Reanalysis (JRA-55) covering the winters (NDJFM) from 1958 to 2018, this study examines the growth and decay mechanisms of the baroclinic wave packet (BWP) inferred from regression analysis over the North Pacific. Day-to-day kinetic energy (KE) and available potential energy (APE) budget analysis suggest that BWP is driven mainly by baroclinic energy conversion (CPB), barotropic energy conversion (CKB), and the nonlinear term (CKE). CPB acts as a predominant APE source for BWP. Part of CPB acts to overcome the APE loss caused by transient eddy flux and most of it acts as a dominant KE source to drive BWP throughout its lifespan. CKB acts as a KE source before day −1, and as a major KE sink to damp BWP afterward, in which the north–south gradient of the climatological meridional flow plays a key role. Similarly, CKE acts as a KE source before day 0 and as a major KE sink afterward. The damping effect of CKE comes mainly from the scale interaction through the advection of high-frequency meridional momentum by the low-frequency zonal flow. It turns out that the vertical geopotential flux divergence also plays an active role in the dynamical coupling of different vertical BWP parts. There is persistent geopotential flux transfer from the middle-tropospheric layer into the lower- and upper-tropospheric layers, which serves as a major KE source to drive the BWP anomalies for the two layers and a major KE sink for the middle-tropospheric layer where the baroclinic energy conversion is the strongest. Significance Statement Previous studies indicate that baroclinic waves tend to organize into wave packets and are driven by the baroclinic instability. This study finds that the baroclinic waves decay mainly through the barotropic energy conversion and nonlinear processes. The results also indicate that the vertical geopotential flux divergence plays an active role in the dynamical coupling of the BWP anomalies in different layers of the troposphere. It is therefore very important to improve the representations of the climatological-mean flow, wave–mean flow interaction, and wave–wave interaction between high- and low-frequency waves in the midlatitudes, as well as the process of vertical transfer of the geopotential flux in numerical models for a better prediction of weather and climate variability in the extratropic regions.

Carbonate Sedimentation in High-Mineralized Lake Bolshoi Bagan (South of West Siberia): Dependence on Holocene Climate Changes

Abstract ––We present the results of comprehensive studies of Holocene bottom sediments from the shallow hypersaline (mineralization up to 282 g/L) Lake Bolshoi Bagan, located in the East Baraba lowland (south of Western Siberia). The research methods include X-ray diffractometry (XRD), IR spectroscopy, laser granulometry, scanning electron microscopy, elemental analysis of sediments and pore water, radiocarbon (14C AMS) dating. It has been found that during the Holocene an intensive authigenic mineral formation took place in the lake basin; gypsum, halite and carbonates of calcite-dolomite series dominate among the newly formed mineral phases. Mg-calcites with different Mg contents, excess-Ca dolomites, aragonite and occasionally Mg-siderite have been found in the assemblage of carbonate minerals by mathematical modeling of complex XRD patterns. Mineralogical and crystallochemical studies, supplemented by the results of geochemical analyses, allowed us to identify four stages of the evolution of Lake Bolshoi Bagan in the Holocene, due to regional climate variations. The boundaries of the stages in general correspond to the boundaries of the climatostratigraphic phases by the Blytt–Sernander system: Stage I (the end of the Boreal) – the lake formation, humid climate; Stage II (Atlantic) – climate aridization, shallowing of the lake; Stage III (Subboreal) – unstable climate, frequent change of conditions; Stage IV (Subatlantic) – moderately cool and dry climate.

Survival rates in the world's southernmost forest bird community.

The Magellanic sub-Antarctic Forest is home to the world's southernmost avian community and is the only Southern Hemisphere analogue to Northern Hemisphere temperate forests at this latitude. This region is considered among the few remaining pristine areas of the world, and shifts in environmental conditions are predominantly driven by climate variability. Thus, understanding climate-driven demographic processes is critical for addressing conservation issues in this system under future climate change scenarios. Here, we describe annual survival patterns and their association with climate variables using a 20-year mark-recapture data set of five forest bird species in the Cape Horn Biosphere Reserve. We develop a multispecies hierarchical survival model to jointly explore age-dependent survival probabilities at the community and species levels in a group of five forest passerines. At the community level, we assess the association of migratory behavior and body size with survival, and at the species level, we investigate the influence of local and regional climatic variables on temporal variations of survival. We found a positive effect of precipitation and a negative effect of El Niño Southern Oscillation on juvenile survival in the white-crested Elaenia and a consistent but uncertain negative effect of temperature on survival in juveniles and 80% of adults. We found only a weak association of climate variables with survival across species in the community and no temporal trends in survival for any of the species in either age class, highlighting apparent stability in these high austral latitude forests. Finally, our findings provide an important resource of survival probabilities, a necessary input for assessing potential impacts of global climate change in this unique region of the world.

Enso and climate variability in Papua

The interaction of sea-atmosphere in the middle and east equators of the Pacific Ocean identified as El-Niño and Southern Oscillation (ENSO) is one of the interannual climate variability in Indonesia. Extremes phase ENSO, EL-Niño, and La-Niña have significant impacts on all sectors including agriculture, maritime, fishery, healthy, forest fire, transportation, etc. To anticipate ENSO impacts, it is required to identify the impacts of ENSO on climate variability in specific regions. In this study, we analyze the impact of ENSO on rainfall characteristics in several areas in Papua Islands namely Merauke, Jayapura, Manokwari, and Wamena. The result of the analysis reveals that the rainfall characteristics in Merauke, Jayapura, Manokwari, and Wamena are influenced by ENSO with different influences among areas. In general, onset of the rainy season is earlier in La Nina years in comparison to the normal year and the onset of the dry season is come in advance in El-Niño years. The annual rainfall in La-Nina year is higher than in normal years and El-Niño year is lower than in normal years. The anomaly of rainfall as impact ENSO varies differently among areas in Papua.

Suboptimal host tree benefits the overwintering of a destructive forest insect pest

Winter represents a stressful period for many organisms, and terrestrial insects are particularly susceptible to adverse thermal conditions. However, exposure to thermal stress and its effects on insect survival and performance can be modulated by various external factors. In forest systems, the overwintering microsite, stand structure, and regional climatic conditions may play a role in overwintering survival and performance at the individual microsite, local stand, and landscape level, respectively. To better understand the effects of these potential influences, rarely examined simultaneously, we deployed wild and lab-reared diapausing spruce budworm in a series of field experiments established across a range of spatial scales.Overwintering survival was higher on black spruce than balsam fir, likely owing to differences in substrate structure (and hence microsite quality/availability) between these two hosts. At the stand level, neither tree species nor age had an impact on insect survival; however, we observed a positive carryover effect of overwintering in a black spruce stand, enhancing performance in post-diapause development, possibly owing to buffering against warm spells during winter. Lastly, despite exposure to a broad range of winter temperatures across an extensive latitudinal gradient, overwintering survival was high (>80%) and did not vary at the landscape level.Our results indicate that insect overwintering was influenced by environmental factors at multiple spatial scales. Interestingly, despite it being considered a poor host for larval feeding, overwintering on black spruce clearly benefited spruce budworm survival and post-diapause performance. Secondly, microsite and stand-level factors had a greater impact than did regional climate variation. Collectively, these findings highlight the importance of finer-scale environmental factors on larval overwintering at both the lethal and sub-lethal level, with implications for basic and applied ecology of this iconic forest insect pest.

CADTEP: A new daily quality‐controlled and homogenized climate database for Catalonia (1950–2021)

AbstractNew daily minimum temperature (TN), maximum temperature (TX) and precipitation amount (PPT) database CADTEP (CAtalan Daily TEmperature and Precipitation data set) has been developed for Catalonia, Spain. The source dataset consists of the available climate records from Catalonia provided by the State Meteorology Agency of Spain (AEMET) and the Catalan Meteorological Service (SMC). We selected the long and fairly complete records and created further long series by merging the records of nearby stations. Finally, 26 TN, 26 TX and 72 PPT time series covering the period 1950–2021 have been accepted for CADTEP from the several hundreds of, but mostly much shorter time series. This database has sufficiently dense time series to reach accurate estimates of regional climate variability. CADTEP time series were subjected to thorough quality control and time series homogenization. In the quality control, many shorter series were still in use. Both in quality control and time series homogenization, several series surrounding Catalonia, but close to the borders, were also considered to achieve a higher data accuracy in CADTEP. The homogenization was performed with ACMANTv5.1. In this new version of ACMANT, metadata dates pointing on likely occurrences of nonclimatic changes (breaks) are contemplated in the homogenization as sure break positions. Finally, we examined the trend and variability of TN, TX and PPT over 1950–2021 using CADTEP. Differences between the use of homogenized and raw data, as well as between the inclusion and exclusion of metadata use in the homogenization procedure were controlled. The most important conclusions are related to the trend analysis, namely the speed of the warming of summer TX is faster than in other seasons, faster than the warming of TN in general, and the triple of the mean global warming speed.

Drought from the 1970s to the 1990s and its Influence in the Tropical City of Beni, Eastern DR Congo

Regional and local climate variability has serious consequences on water resources, ecosystems, and socio-economic activities. With the inexistence of rainfall stations, it is important to reconstruct the past climate with existing data and explore new possibilities for monitoring future climate evolution in the tropical city of Beni. The objective of this paper is to date the 1970-1990 drought and determine the rainfall trend in the tropical city of Beni. To this purpose, a 45-year rainfall time series (period 1974-2019) was analyzed using the Standardized Precipitation Index (SPI). The results of the paper indicate that the average annual rainfall ranges from 693 to 3080 mm with an average of 1827 ± 480.65 mm. The Hubert segmentation procedure applied to the rainfall series reveals three breaks (sub-periods): 1974-1979 (mean 1205.7 mm), 1980-2007 (mean 1736.68 mm), and 2008-2019 (mean 2348.01 mm). After the 2000s, the analysis shows an increasing trend in rainfall. A rainfall deficit of 35.20% is recorded during the period 1974-1979 compared to the period 1980-2007 and 22.61% for the period 1980-2007 compared to the period 2008-2019. The results of this study demonstrate that the city of Beni would have suffered from the drought of the years 1970-1990. Future research should focus on the future evolution of rainfall. However, understanding this future evolution requires long-term data, which is not the case for the tropical city of Beni. Therefore, there is a need for policymakers in collaboration with scientific actors to install meteorological stations to collect climate data.

Reconstructing the pattern of late Quaternary climate through sediment-landform assemblages in the Dhauli Ganga valley (upper Ganga catchment), India

The present study focuses on the reconstruction of the pattern of late Quaternary climate variability through sediment-landform assemblages in the monsoon-dominated Dhauli Ganga valley. The South Tibet Detachment System (STDS) is a major litho-tectonic boundary that divides the Dhauli Ganga valley into two broad geomorphic entities. Towards the north of STDS, the valley is wide and “U” shaped, and the rivers have a braid-meandering channel, implying that the valley was carved by glacial sculpturing in the past. Whereas in the south, deep gorges indicate the dominance of fluvial processes. Based on the stratigraphic position and optical chronologies, the lithified moraines were assigned to Marine Isotopic Stage-3 (MIS-3) they were followed by a major deglaciation event represented by moderately lithified outwash gravels. Following this, a second glacier advance of lesser magnitude is dated 21.3 ± 2.2 ka, corresponding to the Last Glacial Maximum (LGM). A gradual recession of the LGM moraines led to the formation of a proglacial lake which probably persisted until around the onset of a pulsating deglaciation stage represented by outwash gravels dated between 13.4 ± 1.6 and 9.4 ± 0.8 ka. This was also the period when the valleys were overwhelmed by a high sediment water ratio, as indicated by temporary impoundments dated between 15.0 ± 1 ka and 10.0 ± 1 ka. Alluvial fan and debris flow sedimentation overwhelm the valley after around 9 ka and continues till the present.Climatically, the older lithified moraines indicate that glaciers advanced during the cooler MIS-4 or MIS-3. The first major deglaciation event seems to represent the pluvial phase of MIS-3. The presence of LGM moraines indicate that the valley responded to the global cooling and associated enhanced westerlies. In contrast, the chronology of outwash gravels suggests that the valley witnessed insolation driven by the early Holocene strengthened Indian Summer Monsoon (ISM). The undated youngest alluvial fans/debris flows are assigned the mid to late Holocene age (<9.5 ka) and seem to have deposited during the declining phase of ISM (low solar insolation). The study suggests that the landform evolution responded to both the global and regional climate variability indicating the sensitivity of the paraglacial valleys in the monsoon-dominated region to the late Quaternary climate variability.

Analysis of regional climate variables by using neural Granger causality

Analysis of regional climate variables by using neural Granger causality

Late Miocene–early Pliocene tectonic to erosional exhumation in the northwest of the Arabia–Eurasia collision zone

AbstractThe exhumation of actively deforming orogenic systems is commonly due to the incision of river systems in response to tectonically driven surface uplift. However, a regional base level and/or climatic variations can also cause erosional exhumation. The temporal and spatial distinction of the dominant mechanism during the topographic evolution of orogens is challenging. Using detailed morphological analyses and thermal modelling of an intrusive body through triple dating (zircon U–Pb, ZHe, and AHe), combined with the previously published structural, detrital, and bedrock low‐temperature thermochronometry (apatite fission track and apatite helium) analysis, the transition from early Oligocene (~27 Ma) and middle Miocene (~12 Ma) tectonic exhumation to late Miocene–early Pliocene (~7–5 Ma) river incision and erosional exhumation in the Talesh Mountains in the NW of the Arabia–Eurasia collision zone was documented. The late Miocene‐early Pliocene incision and the contemporaneous rapid exhumation documented in the Talesh Mountains are related to the base‐level fall of the Caspian Sea due to its isolation from the Paratethys domain. The effect of this base‐level fall then migrated to the margin of the Iranian Plateau and captured the overspilled basins (~4 Ma).

Climate factors rather than human activities controlled NDVI trends across wet meadow areas in the Andes Centrales of Argentina

In the Andes of southern South America, wet meadows are much more productive than nearby arid areas. Human activities, along with climate variations may reduce the productivity of these ecosystems. However, we do not know what the relative effect of climate and human activities on their degradation status is. Here, we first quantified the degradation extent through the temporal trend of normalized difference vegetation index (NDVI), a proxy of productivity, from 1999 to 2017. We did it in 736 wet meadow areas inserted in three nearby zones with contrasting land management. Second, we analyzed the relationship between NDVI and a large-scale mode of climate variability (El Niño Southern Oscillation, ENSO) and regional climate variables (precipitation and temperature) through a structured climate model. Finally, we evaluated human activities’ effects through the temporal trends in the residuals of the climate model. Independently of land management, NDVI trends were mainly negative and affected 56% of the wet meadow areas. The climate model indicated that NDVI increased under La Niña, cool and wet years. Regarding land management, the degradation level was similar across the contrasted land management. Our results suggest that climate factors rather than human activities influenced the degradation process in these areas.

Attribution and Causality Analyses of Regional Climate Variability

A two-step attribution and causality diagnostic is designed by employing singular spectrum analysis to unfold the attributed climate time series into a trajectory matrix and then subjected to an empirical orthogonal function analysis to identify the evolving driving forces, which can finally be related to major climate modes through their independent frequencies by wavelet analysis. Application results from the arid and drought-prone southern Intermountain region of North America are compared with the climate or larger scale forcing diagnosed from slow feature analysis using the sources of the water and energy flux balance. The following results are noted: (i) The changes between the subsequent four 20-year periods from 1930 to 2010 suggest predominantly climate-induced forcing by the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation. (ii) Land cover influences on the changing land cover are of considerably smaller magnitude (in terms of area percentage cover) whose time evolution is well documented from forestation documents. (iii) The drivers of the climate-induced forcings within the last 20 years are identified as the quasi-biennial oscillation and the El Niño–Southern Oscillation by both the inter-annual two-step attribution and the causality diagnostics with monthly scale-based slow feature analysis.

Lake surface temperature retrieved from Landsat satellite series (1984 to 2021) for the North Slave Region

Abstract. Lake surface temperature (LST) is an important attribute that highlights regional weather and climate variability and trends. The spatial resolution and thermal sensors on Landsat platforms provide the capability of monitoring the temporal and spatial distribution of lake surface temperature on small- to medium-sized lakes. In this study, a retrieval algorithm was applied to the thermal bands of Landsat archives to generate a LST dataset (North Slave LST dataset) for 535 lakes in the North Slave Region (NSR) of the Northwest Territories (NWT), Canada, for the period of 1984 to 2021. North Slave LST was retrieved from Landsat 5 Thematic Mapper (TM), Landsat 7 Enhanced Thematic Mapper Plus (ETM+), and Landsat 8 Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS); however, most of the dataset was created from the thermal bands of Landsat 5 (43 %) due to its longevity (1984–2013). Cloud masks were applied to Landsat images to eliminate cloud cover. In addition, a 100 m inward buffer was applied to lakes to prevent pixel mixing with shorelines. To evaluate the algorithm applied, retrieved LST was compared with in situ data and Moderate Resolution Imaging Spectroradiometer (MODIS) LST observations. A good agreement was observed between in situ observations and North Slave LST, with a mean bias of 0.12 ∘C and a root mean squared deviation (RMSD) of 1.7 ∘C. The North Slave LST dataset contains more available data for warmer months (May to September; 57.3 %) compared to colder months (October to April). The average number of images per year for each lake across the NSR ranged from 20 to 45. The North Slave LST dataset, available at https://doi.org/10.5683/SP3/J4GMC2 (Attiah et al., 2022), will provide communities, scientists, and stakeholders with spatial and temporal changing temperature trends on lakes for the past 38 years.

Impact of regional climate change on the mosquito vector Aedes albopictus in a tropical island environment: La Réunion

The recent expansion of Aedes albopictus across continents in both tropical and temperate regions and the exponential growth of dengue cases over the past 50 years represent a significant risk to human health. Although climate change is not the only factor responsible for the increase and spread of dengue cases worldwide, it might increase the risk of disease transmission at global and regional scale. Here we show that regional and local variations in climate can induce differential impacts on the abundance of Ae. albopictus. We use the instructive example of Réunion Island with its varied climatic and environmental conditions and benefiting from the availability of meteorological, climatic, entomological and epidemiological data. Temperature and precipitation data based on regional climate model simulations (3 km × 3 km) are used as inputs to a mosquito population model for three different climate emission scenarios. Our objective is to study the impact of climate change on the life cycle dynamics of Ae. albopictus in the 2070–2100 time horizon. Our results show the joint influence of temperature and precipitation on Ae. albopictus abundance as a function of elevation and geographical subregion. At low-elevations areas, decreasing precipitation is expected to have a negative impact on environmental carrying capacity and, consequently, on Ae. albopictus abundance. At mid- and high-elevations, decreasing precipitation is expected to be counterbalanced by a significant warming, leading to faster development rates at all life stages, and consequently increasing the abundance of this important dengue vector in 2070–2100.