Climate, Volume 9, Issue 4 (April 2021) – 18 articles

Climate models project vulnerability to global warming in low-income regions, with important implications for sustainable development. While food crops are the priority, smallholder cash crops support food security, education, and other priorities. Despite its importance as a populous region subject to substantial climate change, West Africa has received relatively slight attention in spatial assessments of climate impacts. In this region, rainfed cotton (Gossypium hirsutum) provides essential smallholder income. We used a spatially explicit species distribution model to project likely changes in the spatial distribution of suitable climates for rainfed cotton in West Africa. We modeled suitable climate conditions from the recent past (1970–2000) and projected the range of those conditions in 2050 (Representative Concentration Pathways (RCP) 4.5 and 8.5). The suitable area declined by 60 percent under RCP4.5 and by 80 percent under RCP8.5. Of 15 countries in the study area, all but two declined to less than ten percent suitable under RCP8.5. The annual precipitation was the most influential factor in explaining baseline cotton distribution, but 2050 temperatures appear to become the limiting factor, rising beyond the range in which rainfed cotton has historically been grown. Adaptation to these changes and progress on sustainable development goals will depend on responses at multiple scales of governance, including global support and cooperation. Full article

Recent decades have registered the hottest temperature variation in instrumentally recorded data history. The registered temperature rise is particularly significant in the so-called hot spot or sentinel regions, characterized by higher temperature increases in respect to the planet average value and by more marked connected effects. In this framework, in the present work, following the climate stochastic resonance model, the effects, due to a temperature increase independently from a specific trend, connected to the 10⁵ year Milankovitch cycle were tested. As a result, a breaking scenario induced by global warming is forecasted. More specifically, a wavelet analysis, innovatively performed with different sampling times, allowed us, besides to fully characterize the cycles periodicities, to quantitatively determine the stochastic resonance conditions by optimizing the noise level. Starting from these system resonance conditions, numerical simulations for increasing planet temperatures have been performed. The obtained results show that an increase of the Earth temperature boosts a transition towards a chaotic regime where the Milankovitch cycle effects disappear. These results put into evidence the so-called threshold effect, namely the fact that also a small temperature increase can give rise to great effects above a given threshold, furnish a perspective point of view of a possible future climate scenario, and provide an account of the ongoing registered intensity increase of extreme meteorological events. Full article

Radiation management (RM) has been proposed as a conceivable climate engineering (CE) intervention to mitigate global warming. In this study, we used a coupled climate model (MPI-ESM) with a very idealized setup to investigate the efficacy and risks of CE at a local scale in space and time (regional radiation management, RRM) assuming that cloud modification is technically possible. RM is implemented in the climate model by the brightening of low-level clouds (solar radiation management, SRM) and thinning of cirrus (terrestrial radiation management, TRM). The region chosen is North America, and we simulated a period of 30 years. The implemented sustained RM resulted in a net local radiative forcing of −9.8 Wm${}^{-2}$ and a local cooling of −0.8 K. Surface temperature (SAT) extremes (90th and 10th percentiles) show negative anomalies in the target region. However, substantial climate impacts were also simulated outside the target area, with warming in the Arctic and pronounced precipitation change in the eastern Pacific. As a variant of RRM, a targeted intervention to suppress heat waves (HW) was investigated in further simulations by implementing intermittent cloud modification locally, prior to the simulated HW situations. In most cases, the intermittent RRM results in a successful reduction of temperatures locally, with substantially smaller impacts outside the target area compared to the sustained RRM. Full article

The Mediterranean region is an area particularly susceptible to water scarcity and drought. In this work, drought has been analyzed in Italy using multiple timescales of the standardized precipitation index (SPI) evaluated from the Integrated Multi-satellitE Retrievals for Global Precipitation Measurement product from 2000 to 2020. In particular, drought characteristics (severity, duration, and intensity) have been estimated by means of the run theory applied to the SPI values calculated in 3325 grid points falling within the Italian territory. Results clearly indicate that although a high number of drought events has been identified for the short timescale, these events present a lower duration and lesser severity than the long-timescale droughts. The main outcomes of this study, with the indication of the spatial distribution of the drought characteristics in Italy, allow identifying the areas that could also face water stress conditions in the future, thus requiring drought monitoring and adequate adaptation strategies. Full article

Climate change leverages landscape transformations and exerts variable pressure on natural environments and rural systems. Earlier studies outlined how Mediterranean Europe has become a global hotspot of climate warming and land use change. The present work assumes the olive tree, a typical Mediterranean crop, as a candidate bioclimatic indicator, delineating the latent impact of climate aridity on traditional cropping systems at the northern range of the biogeographical distribution of the olive tree. Since the olive tree follows a well-defined latitude gradient with a progressive decline in both frequency and density moving toward the north, we considered Italy as an appropriate case to investigate how climate change may (directly or indirectly) influence the spatial distribution of this crop. By adopting an exploratory approach grounded in the quali-quantitative analysis of official statistics, the present study investigates long-term changes over time in the spatial distribution of the olive tree surface area in Northern Italy, a region traditionally considered outside the ecological range of the species because of unsuitable climate conditions. Olive tree cultivated areas increased in Northern Italy, especially in flat districts and upland areas, while they decreased in Central and Southern Italy under optimal climate conditions, mostly because of land abandonment. The most intense expansion of the olive tree surface area in Italy was observed in the northern region between 1992 and 2000 and corresponded with the intensification of winter droughts during the late 1980s and the early 1990s and local warming since the mid-1980s. Assuming the intrinsic role of farmers in the expansion of the olive tree into the suboptimal land of Northern Italy, the empirical results of our study suggest how climate aridity and local warming may underlie the shift toward the north in the geographical range of the olive tree in the Mediterranean Basin. We finally discussed the implications of the olive range shift as a part of a possible landscape scenario for a more arid future. Full article

Climatic events express the dynamics of the Earth’s oceans and atmosphere, but are profoundly personal and social in their impacts, representation and comprehension. This paper explores how knowledge of the climate has multiple scales and dimensions that intersect in our experience of the climate. The climate is objective and subjective, scientific and cultural, local and global, and personal and political. These divergent dimensions of the climate frame the philosophical and cultural challenges of a dynamic climate. Drawing on research into the adaptation in Australia’s Murray Darling Basin, this paper outlines the significance of understanding the cultural dimensions of the changing climate. This paper argues for greater recognition of the ways in which cultures co-create the climate and, therefore, that the climate needs to be recognised as a socio-natural hybrid. Given the climate’s hybrid nature, research should aim to integrate our understanding of the social and the natural dimensions of our relationships to a changing climate. Full article

Climate analyses at a local scale are an essential tool in the field of sustainable development. The evolution of reanalysis datasets and their greater reliability contribute to overcoming the scarcity of observed data in the southern areas of the world. The purpose of this study is to compute the reference monthly values and ranges of maximum and minimum temperatures for the eight main inhabited villages of North Horr Sub-County, in northern Kenya. The official ten-day dataset derived from the Kenyan Meteorological Department (KMD), the monthly datasets derived from the ERA-Interim reanalysis (ERA), the Observational-Reanalysis Hybrid (ORH) and the Climate Limited Area Mode driven by HadG-EM2-ES (HAD) are assessed on a local scale using the most common statistical indices to determine which is more reliable in representing monthly maximum and minimum temperatures. Overall, ORH datasets showed lower biases and errors in representing local temperatures. Through an innovative methodology, a new set of monthly mean temperature values and ranges derived from ORH datasets are calculated for each location in the study area, in order to guarantee to locals an historical benchmark to compare present observations. The findings of this research provide insights for environmental risk management, supporting local populations in reducing their vulnerability. Full article

Mopani District Municipality in the northeast of South Africa is largely semi-arid and frequently affected by meteorological droughts. The recent 2015/16 event had devastating impacts on water levels, crop yields, livestock herds and rural livelihoods. We investigated the nature of the drought hazard; its impacts, including vulnerability of rural communities in Mopani District and adaptation strategies they have employed to cope with drought. A mixed methods approach with both quantitative and qualitative datasets was used. The district was divided into two distinct climatic areas: the drier eastern lowveld and the wetter western bushveld. Questionnaires were administered among community members whilst key informant interviews were conducted among relevant government and municipal officials. Climate data was used to characterize historical drought using a Standardized Precipitation and Evapotranspiration Index whilst vegetation anomaly maps were used to demonstrate impacts. Spatially distinct patterns of drought conditions were evident with harsh and dry conditions towards the east. It was found that nearly half the time there is some form of drought or another in the district mostly linked to the remote El Nino phenomenon. In several areas, rain-fed agriculture is no longer tenable, with a direct impact on rural livelihoods. A Household Vulnerability Index determined variable levels of vulnerability such that different strategies are employed to adapt to drought some of which cause environmental problems. Local government intervention strategies include supply of seeds and fertilisers, providing cheap fodder and supplying water using trucks. The findings of this study contribute to disaster risk reduction efforts in a region that is highly vulnerable to current and future climate-risks. Full article

Local knowledge can be a strategy for coping with extreme events and adapting to climate change. In Mexico, extreme events and climate change projections suggest the urgency of promoting local adaptation policies and strategies. This paper provides an assessment of adaptation actions based on the local knowledge of coffee farmers in southern Mexico. The strategies include collective and individual adaptation actions that farmers have established. To determine their viability and impacts, carbon stocks and fluxes in the system’s aboveground biomass were projected, along with water balance variables. Stored carbon contents are projected to increase by more than 90%, while maintaining agroforestry systems will also help serve to protect against extreme hydrological events. Finally, the integration of local knowledge into national climate change adaptation plans is discussed and suggested with a local focus. We conclude that local knowledge can be successful in conserving agroecological coffee production systems. Full article

Arctic environments experience rapid climatic changes as air temperatures are rising and precipitation is increasing. Rivers are key elements in these regions since they drain vast land areas and thereby reflect various climatic signals. Zackenberg River in northeast Greenland provides a unique opportunity to study climatic influences on discharge, as the river is not connected to the Greenland ice sheet. The study aims to explain discharge patterns between 1996 and 2019 and analyse the discharge for correlations to variations in air temperature and both solid and liquid precipitation. The results reveal no trend in the annual discharge. A lengthening of the discharge period is characterised by a later freeze-up and extreme discharge peaks are observed almost yearly between 2005 and 2017. A positive correlation exists between the length of the discharge period and the Thawing Degree Days ($r=0.52,p<0.01$), and between the total annual discharge and the annual maximum snow depth ($r=0.48,p=0.02$). Thereby, snowmelt provides the main source of discharge in the first part of the runoff season. However, the influence of precipitation on discharge could not be fully identified, because of uncertainties in the data and possible delays in the hydrological system. This calls for further studies on the relationship between discharge and precipitation. The discharge patterns are also influenced by meltwater from the A.P. Olsen ice cap and an adjacent glacier-dammed lake which releases outburst floods. Hence, this mixed hydrological regime causes different relationships between the discharge and climatic trends when compared to most Arctic rivers. Full article

Rapid urbanization and increasing population in cities with a large portion of them settled in deprived neighborhoods, mostly defined as slum areas, have escalated inequality and vulnerability to natural disasters. As a result, monitoring such areas is essential to provide information and support decision-makers and urban planners, especially in case of disaster recovery. Here, we developed an approach to monitor the urban deprived areas over a four-year period after super Typhoon Haiyan, which struck Tacloban city, in the Philippines, in 2013, using high-resolution satellite images and machine learning methods. A Support Vector Machine classification method supported by a local binary patterns feature extraction model was initially performed to detect slum areas in the pre-disaster, just after/event, and post-disaster images. Afterward, a dense conditional random fields model was employed to produce the final slum areas maps. The developed method detected slum areas with accuracies over 83%. We produced the damage and recovery maps based on change analysis over the detected slum areas. The results revealed that most of the slum areas were reconstructed 4 years after Typhoon Haiyan, and thus, the city returned to the pre-existing vulnerability level. Full article

The North Equatorial Countercurrent (NECC) is an eastward zonal current closely related to an El Niño Southern Oscillation (ENSO) event. This paper investigated the variations of NECC in the Western Pacific Ocean over 25 years (1993–2017) using satellite data provided by the Copernicus Marine Environment Monitoring Service (CMEMS) and the Remote Sensing System (RSS). The first mode of empirical orthogonal function (EOF) analysis showed that the NECC strengthened or weakened in each El Niño (La Niña) event during the developing or mature phase, respectively. We also found that the NECC shifting was strongly coincidental with an ENSO event. During the developing phase of an El Niño (La Niña) event, the NECC shifted southward (northward), and afterward, when it entered the mature phase, the NECC tended to shift slightly northward (southward). Moreover, the NECC strength was found to have undergone a weakening during the 2008–2017 period. Full article

Traditional drought monitoring is based on observed data from both meteorological and hydrological stations. Due to the scarcity of station observation data, it is difficult to obtain accurate drought distribution characteristics, and also tedious to replicate the large-scale information of drought. Thus, Gravity Recovery and Climate Experiment (GRACE) data are utilized in monitoring and characterizing regional droughts where ground station data is limited. In this study, we analyzed and assessed the drought characteristics utilizing the GRACE Groundwater Drought Index (GGDI) over four major river basins in India during the period of 2003–2016. The spatial distribution, temporal evolution of drought, and trend characteristics were analyzed using GGDI. Then, the relationship between GGDI and climate factors were evaluated by the method of wavelet coherence. The results indicate the following points: GRACE’s quantitative results were consistent and robust for drought assessment; out of the four basins, severe drought was noticed in the Cauvery river basin between 2012 and 2015, with severity of −27 and duration of 42 months; other than Godavari river basin, the remaining three basins displayed significant negative trends at monthly and seasonal scales; the wavelet coherence method revealed that climate factors had a substantial effect on GGDI, and the impact of Southern Oscillation Index (SOI) on drought was significantly high, followed by Sea Surface Temperature (SST) Index (namely, NINO3.4) and Multivariate El Niño–Southern Oscillation Index (MEI) in all the basins. This study provides reliable and robust quantitative result of GRACE water storage variations that shares new insights for further drought investigation. Full article

Global climate change is expected to impact future precipitation and surface temperature trends and could alter local hydrologic systems. This study assessed the likely hydrologic responses and changes in streamflow due to future climate change within the Alabama River Basin (ARB) for the mid-21st century 2045 (“2030–2060”) and end-21st century 2075 (“2060–2090”). Using an integrated modeling approach, General Circulation Model (GCM) datasets; the Centre National de Recherches Météorologiques Climate Model 5 (CNRM-CM5), the Community Earth System Model, version 1–Biogeochemistry (CESM1- BGC.1), and the Hadley Centre Global Environment Model version 2 (HADGEM2-AO.1), under medium Representative Concentration Pathway (RCP) 4.5, and based on World Climate Research Program (WCRP)’s Couple Model Intercomparison Phase 5 (CMIP5), were assimilated into calibrated Soil and Water Assessment Tool (SWAT). Mann–Kendall and Theil Sen’s slope were used to assess the trends and magnitude of variability of the historical climate data used for setting up the model. The model calibration showed goodness of fit with minimum Nash–Sutcliffe Efficiency (NSE) coefficient values of 0.83 and Coefficient of Determination (R²) of 0.88 for the three gages within the ARB. Next, the research assessed changes in streamflow for the years 2045 and 2075 against that of the reference baseline year of 1980. The results indicate situations of likely increase and decrease in mean monthly streamflow discharge and increase in the frequency and variability in peak flows during the periods from the mid to end of the 21st century. Seasonally, monthly streamflow increases between 50% and 250% were found for spring and autumn months with decreases in summer months for 2045. Spring and summer months for 2075 resulted in increased monthly streamflow between 50% and 300%, while autumn and spring months experienced decreased streamflow. While the results are prone to inherent uncertainties in the downscaled GCM data used, the simulated dynamics in streamflow and water availability provide critical information for stakeholders to develop sustainable water management and climate change adaptation options for the ARB. Full article

Climate change is significantly affecting ecosystem services and leading to strong impacts on the extent and distribution of glaciers and vegetation. In this context, species distribution models represent a suitable instrument for studying ecosystem development and response to climate warming. This study applies the maximum entropy model, MaxEnt, to evaluate trends and effects of climate change for three environmental indicators in the area of the Alpi Marittime Natural Park under the Municipality of Entracque (Italy). Specifically, this study focuses on the magnitude of the retreat of six glaciers and on the distribution of two different plant communities, Alnus viridis scrub and Fagus sylvatica forest associated with Acer pseudoplatanus and tall herbs (megaforbie), in relation to predicted increases in mean temperatures. MaxEnt software was used to model and observe changes over a thirty-year period, developing three scenarios: a present (2019), a past (1980) and a future (2050) using 24 “environmental layers”. This study showed the delicate climate balances of these six small glaciers that, in the next 30 years, are likely to undergo an important retreat (≈−33%) despite the high altitude and important snowfall that still characterize the area. At the same time, it is predicted that the two plant communities will invade those higher altitude territories that, not so long ago, were inhospitable, expanding their habitat by 50%. The MaxEnt application to glaciers has shown to be an effective tool that offers a new perspective in the climate change field as well as in biodiversity conservation planning. Full article

Several studies have indicated that the social, economic and other impacts of global warming can be linked with changes in the frequency and intensity of extreme weather/climate events. Developing countries, particularly in the African region, are highly affected by extreme events such as high temperature, usually followed/accompanied by drought. Therefore, studying the probability of occurrence and return period of extreme temperatures, and possible change in these parameters, is of high importance for climate-related policy making and preparedness works in the region. This study aims to address these issues by assessing probability of exceedance and return period of extremes in annual maximum and annual mean temperatures. The analyses of historical data in this study showed that extremes in both annual maximum and mean temperature are highly likely to be exceeded more often in the future compared to the past. For the extreme event marker (threshold) defined in this study, probability of 3 exceedances in the following 19 years (for instance), at any gridpoint, is estimated to be at least 10% for extremes in annual maxima and at least 15% for those in annual means. Most places in the region, however, have much higher (up to 20%) probability of exceedance. The estimated probability of exceedance has shown increasing tendency with time. Return period, based on the most recent data, of extremes in annual maximum temperature is found to be less than 6.5 years at about 48% of the gridpoints in the region. Similarly, return period of extremes in annual mean temperature is estimated to be less than 5.5 years at about 82% of places in the region. These estimates have also shown a strong tendency of getting shorter as time goes on. On average, extremes in annual mean temperature were found to have shorter return periods (4–7 years) compared to those in annual maximum temperature (6–10 years), at 95% confidence. The empirical results presented in this study are generally in agreement with IPCC’s projections of increased warming trend. This data-driven, robust method is used in the present study and the results can also be considered as an alternative approach for detecting changes in climate via estimating and assessing possible changes in frequency of extreme events with time. Full article

Local strategies and policies are key in climate adaptation, although research shows significant barriers to progress. Sweden, often seen as progressive in climate change issues, has struggled in adopting a sufficient local climate adaptation organization. This article aimed to describe and analyze the climate adaptation organization in 13 Swedish municipalities from five perspectives: Problem framing, administrative and political agency, administrative and political structures, measures and solutions, and the role of learning. The mapping of these perspectives provides an opportunity to analyze barriers to local climate adaptation. Key policy documents have been studied including climate adaptation plans, crisis management plans, and regulatory documents, as well as documents from private consultants. This study showed that few municipalities have a formal organization for climate adaptation, clear structures, political support, and specific climate adaptation plans. At the same time, many of the municipalities are planning for transformation, due to a push from the county board, a lead agency in climate adaptation. There are also ample networks providing opportunities for learning among municipalities and regions. This study concluded that one key barrier is the lack of focus and prioritization in a majority of the municipalities, leaving the administrators, often planners, in a more activist position. The need for organizational mainstreaming and resources is emphasized. Full article

Due to the combination of climate change and the rapid growth in urban populations in Africa, many urban areas are encountering exacerbated urban heat island (UHI) effects. It is important to understand UHI effects in order to develop suitable adaptation and mitigation strategies. However, little work has been done in this regard in Africa. In this study, we compared surface UHI (SUHI) effects between cities located in different climate zones in East Africa, investigating how they change, both spatially and temporally. We quantified the annual daytime and night-time SUHI intensities in the five most populated cities in East Africa in 2003 and 2017, and investigated the links to urban area size. We consider the possible drivers of SUHI change and consider the implication for future development, highlighting the role of factors such as topography and building/construction materials. We suggest that UHI mitigation strategies targeting East African cities may benefit from more comprehensive analyses of blue and green infrastructure as this offers potential opportunities to enhance human comfort in areas where UHI effects are highest. However, this needs careful planning to avoid increasing associated issues such as disease risks linked to a changing climate. Full article