Climate

The aims of this study are to assess the impacts of accelerated climate change on summer maximum temperatures since the early 1990s in the Australian city of Sydney’s eastern coastal and western inland suburbs. Western Sydney currently experiences far more intense summer (December–March) heat waves than coastal Sydney, with maximum temperatures exceeding those of coastal Sydney by up to 10 °C. Aside from increased bushfire danger, extreme temperature days pose health and socio-economic threats to western Sydney. Permutation tests of consecutive summer periods, 1962–1991 and 1992–2021, are employed to determine the differential climate change impacts on maximum summer temperatures at two locations: Sydney and Richmond, representative of eastern and western Sydney, respectively. Attribution of observed maximum summer temperature trends in Sydney and Richmond was performed using machine learning techniques applied to known Australian region oceanic and atmospheric climate drivers. It was found that there is a marked disparity in the percentage of summer days above the 95th percentile during the accelerated climate change period (1992–2021) between Richmond (+35%) and Sydney (−24%), relative to 1962–1991. The climate drivers detected as attributes were similar in both Sydney and Richmond, but, unsurprisingly, Sydney was more affected than Richmond by the oceanic climate drivers. Full article

In the present work, we investigate the solar radiation climate of Saudi Arabia, using solar radiation data from 43 sites in the country covering the period 2013–2021. These data include hourly values of global, G, and diffuse, G_d, horizontal irradiances from which the direct, G_b, horizontal irradiance is estimated. The diffuse fraction, k_d; the direct-beam fraction, k_b; and the ratio k_e = G_d/G_b, are used in the analysis. Solar maps of the annual mean G, G_d, k_d, k_b, and k_e are prepared for Saudi Arabia under all- and clear-sky conditions, which show interesting but explainable patterns. Additionally, the intra-annual and seasonal variabilities of these parameters are presented, and regression equations are provided. We find that G_b has a negative linear relationship with k_d; the same applies to G with respect to k_d or the latitude, φ, of the site. It is shown that k_d and k_b can reflect the scattering and absorption effects of the atmosphere on solar radiation, respectively; therefore, they can be used as atmospheric scattering and absorption indices. Part of the analysis considers the defined solar energy zones in Saudi Arabia. Full article

Despite mitigation and adaptation efforts, the residual risks of climate change will continue to impact the most vulnerable communities globally. Highly exposed regions, such as the Pacific Islands, will continue to experience profound negative loss and damage as a result of climate change, which will challenge current ways of life. Knowledge on the extent to which regional and national climate change polices can identify and respond to non-economic loss and damage (NELD) is limited. From the perspectives of stakeholders in the Pacific Islands region, this research aims to gain insights into how regional and national policies are responding to NELD, as the well as the barriers, shortcomings, and requirements for future responses. Utilising a mixed qualitative–quantitative approach, this research explores the perspectives of expert informants, including those from the government, donors and development partners, civil society, intergovernmental organisations, and other relevant bodies, such as universities. The key findings of this study indicate that current policy responses include a regional policy that integrates disaster and climate change losses, national efforts to preserve traditional and local knowledge, national adaptation and resilience planning, community-based projects, and relocation and resettlement. Additionally, NELD is a relatively new concept for policymakers, practitioners, and researchers, and it is difficult to conceptualise the diversity of issues related to NELD in the region. Owing to this poor understanding, a key gap relates to the dominance of the economic lens when characterising climate-induced impacts in the region. As such, there is a limited holistic consideration of climate change impacts, and thus a limited appreciation of the interrelated factors of NELD within policy responses that then cascade towards communities. Finally, the paper outlines key policy insights as follows: policies on integration, adaptation, resilience planning, relocation and resettlement have advanced; the economic lens dominates when characterising climate-induced impacts on the region; there is a limited appreciation of the interrelated factors of NELD; and there exists a need to account for residual and intangible losses to land, culture, traditional knowledge, biodiversity, ecosystem services, and human agency. The insights gained from this research can provide a practical basis for guiding local to regional action and help support and design comprehensive risk management solutions in order to address NELD associated with climate change. Full article

Extreme rainfall events cause diverse loss of life and economic losses. These disasters include flooding, landslides, and erosion. For these intense rainfall events, one can statistically estimate the time when a given rainfall volume will occur. Initially, this work estimated rainfall volumes for the mountainous region of Rio de Janeiro, and the frequency with which rainfall events occur. For this, we analyzed daily precipitation data using the ANOBES method and the Gumbel statistical distribution to estimate return times. Extreme prec’ipitation volumes of up to 240 mm per day were identified in some locations, with 100 years or more return periods. On 11 January 2011 precipitation volumes were high, but on 12 January they were extreme, similar to the 100-year return time data. The analysis method presented enables the determination of the return time of heavy rainfall, assisting in the prevention of its effects. Knowledge of the atmospheric configuration enables decision support. The atmospheric systems that combined to cause the event were local circulations (orographic and sea breeze) and large-scale systems (SACZ and frontal systems). Full article

Research on solid precipitation and snow cover, especially in mountainous areas, suffers from problems related to the lack of on-site observations and the low reliability of measurements, which is often due to instruments that are not suitable for the environmental conditions. In this context, the study area is the Monti Sibillini National Park, and it is no exception, as it is a mountainous area located in central Italy, where the measurements are scarce and fragmented. The purpose of this research is to provide a characterization of the snow cover with regard to maximum annual snow depth, average snow depth during the snowy period, and days with snow cover on the ground in the Monti Sibillini National Park area, by means of ground weather stations, and also analyzing any trends over the last 30 years. For this research, in order to obtain reliable snow cover data, only data from weather stations equipped with a sonar system and manual weather stations, where the surveyor goes to the site each morning and checks the thickness of the snowpack and records, it were collected. The data were collected from 1 November to 30 April each year for 30 years, from 1991 to 2020; six weather stations were taken into account, while four more were added as of 1 January 2010. The longer period was used to assess possible ongoing trends, which proved to be very heterogeneous in the results, predominantly negative in the case of days with snow cover on the ground, while trends were predominantly positive for maximum annual snow depth and distributed between positive and negative for the average annual snow depth. The shorter period, 2010–2022, on the other hand, ensured the presence of a larger number of weather stations and was used to assess the correlation and presence of clusters between the various weather stations and, consequently, in the study area. Furthermore, in this way, an up-to-date nivometric classification of the study area was obtained (in terms of days with snow on the ground, maximum height of snowpack, and average height of snowpack), filling a gap where there had been no nivometric study in the aforementioned area. The interpolations were processed using geostatistical techniques such as co-kriging with altitude as an independent variable, allowing fairly precise spatialization, analyzing the results of cross-validation. This analysis could be a useful tool for hydrological modeling of the area, as well as having a clear use related to tourism and vegetation, which is extremely influenced by the nivometric variables in its phenology. In addition, this analysis could also be considered a starting point for the calibration of more recent satellite products dedicated to snow cover detection, in order to further improve the compiled climate characterization. Full article

Based on the climate proxy data, several recent studies have concluded that the Ming dynasty’s reign in China coincided with the Little Ice Age, a global crisis. In response, scholars have published several reports in recent years addressing this topic. This paper presents a comprehensive overview of the current research findings in English regarding this subject and identifies existing research gaps. The author proposes that the impact of climate on different regions during the late Ming period remains largely underexplored. Furthermore, scholars must exercise caution when assuming that adverse climatic conditions uniformly impacted the Ming empire during the Little Ice Age. This paper also highlights the use of simplistic models by scholars linking cold and dry climates to crop failure, floods, droughts, population decline, and other factors. However, any straightforward models that presume causal determination risk ignoring historical facts. Full article

The sea level trend in the equatorial Malacca Strait is a significant issue that needs to be reviewed since it is an area of interest. Assessing its future impact on estuarine tidal characteristics is worth studying because it relates to the potency of coastal damages. This study aimed to discuss the relationship between sea level variations and anomalies and their possible triggering factors and to estimate the future impacts on the tidal properties in the estuarine zone. Tide gauge and altimetry data in the Tanjong Pagar site were used to assess the sea level trends over 27 years of observation (from 1992 to 2019). Both altimetry and tide gauge data showed an upward trend, with 0.24 cm/year and 0.39 cm/year, respectively. Due to the near-equatorial area of interest, sea level variability is more synchronized with ENSO rather than IOD. At some points, ENSO shapes the sea level fluctuation, with an R² of less than 10%. For specific periods, the coupling effects between MJO and La Niña may trigger higher evaporation in the maritime continent, triggering increasing sea levels. Of particular concern, among the other assessed factors, the zonal currents and winds (wind-driven currents) are strongly correlated with sea level variations, primarily during the NE monsoon and the second transitional periods, with a determination coefficient of about 18–36%. As a result of sea level rises, it is estimated that tidal constituent amplitudes will increase by about 8.9% and 18.3% in 2050 and 2100, respectively. The increase in tidal range will possibly relate to the tidal bore passage in the Kampar estuary. Therefore, more advanced hydrodynamic modeling is necessary to determine the impact of sea level rises on tidal bore generation. Full article

The wind is one of the most important and studied variables globally, essential to several sectors, for example, energy. Therefore, this study assesses the wind regime and analysis trends in three locations within the Paraná state, Brazil. The historical series were recorded between 1976 and 2010 at conventional meteorological stations belonging to the Brazilian National Institute of Meteorology. WRPLOT version 8.0.0 software was used for elaborating wind roses and histograms in the annual and seasonal scales. Detection of trends and temporal rupture points was performed using different statistical methods (Run, Mann–Kendall, Pettitt and Shapiro–Wilk tests) for all meteorological stations. All statistical tests were conducted using the R software version 3.3.2. On a seasonal scale, summer and spring present the highest wind speeds in the Curitiba and Paranaguá stations due to meteorological systems on different scales, such as the South Atlantic subtropical anticyclone and frontal systems. The Mann–Kendall test revealed that Castro presented statistical significance in reducing wind speed, with a decrease of 0.23 m/s per decade for the annual scale and 0.23 m/s per decade during the autumn season. These ruptures indicated a decrease in wind speed in Curitiba and Paranaguá for the spring season. The Pettitt test revealed a break point detection in the data series in Curitiba station, likely due to urban expansion that started in the 1980s, reducing wind speed, especially in winter and spring. These trends and ruptures revealed a significant reduction in wind speed, possibly due to the interaction between natural climate changes and the increase in surface roughness resulting from land use and urbanization changes. Full article

The Balkan Peninsula is a geographical region under various large-scale climatic influences, one of the most significant being the Mediterranean Sea in the southwest and the continent in the northeast. The novelty of this study is that the border between the zones with prevailing maritime or continental climate conditions is clearly identified by the month with the highest precipitation during the year. We use the gridded data product TS_4.06 of the Climatic Research Unit for monthly precipitation to identify the timing of the maximum rainfall at different locations. The grid boxes with highest precipitation in the cold part of the year (October to March) are considered to be under prevailing Mediterranean influences and, on the contrary, the ones with the highest precipitation are in the warm part of the year (April to September); these are climates with prevailing continental characteristics. In general, this border separates the zones with Cs and Dw types of climates. Its spatial variability at a decadal time-scale is discussed for the period from 1901–2021 and a general weakening of the Mediterranean influence over the Balkan Peninsula is found. However, for the last three decades, from 1991–2021, the tendency is the opposite. A periodicity of ~20 years is identified, suggesting that during the decade of 2020–2030, the Mediterranean influence in this region will dominate. Full article

The aim of this work is to study the variability of winter (monthly mean of DJF) air temperatures in Saudi Arabia. The study of the coefficient of variation (CV) of winter air temperature time series shows that the CV is a function of latitude, decreasing generally gradually from north to south. The highest values of CV during the winter season are mainly because of the migrating extratropical cyclones (Mediterranean cyclones) from west to east, and active subtropical jet, as well as the polar jet. The trend analysis illustrates that all stations have positive trends for the wintertime series. The study of decadal fluctuations in the behavior of winter temperature shows that the period from 1982 to 2010 is characterized in general by negative trend values in most northern stations of Saudi Arabia. In the middle of Saudi Arabia, negative trend values also appear but for the period 1983 to 2003. The southern and middle stations are distinguished by a positive trend during the period from 2003 to 2018. Full article

A one-dimensional hydraulic HEC-RAS model was developed to forecast the change in salinity in the tributaries of the Co Chien and Hau Rivers in Tra Vinh province, Vietnam. The boundary data includes river discharge at Can Tho and My Thuan, water levels, and salinity at coastal monitoring stations. Six monitoring stations along the Co Chien River and Hau River were selected to study salinity changes. Four scenarios for the period 2020–2050 were selected, including SLR17, SLR22, SLR26L, and SLR26H, corresponding to sea level rise (17, 22, and 26 cm) and upstream river discharge decrease (in the ranges of 100–128% and 80–117% at Can Tho and My Thuan, respectively) in the dry season based on new climate change scenarios in Vietnam and previous studies. The results highlight that when the average discharge at Can Tho and My Thuan reduces, the salinity increases more significantly than the impact of sea level rise. Salinity at the monitoring stations in Tra Vinh province is projected to increase within the ranges of 4–21% and 3–29% along the Co Chien River and Hau River, respectively. In addition, sea level rise is seen to affect the discharge distribution into the Co Chien River. It suggests an urgent need to raise farmers’ awareness of climate change adaptation, investment in production equipment, and appropriate regulation of riverbed mining and activities upstream in the Mekong River. Full article

The objective of this study is to gain a holistic and enhanced understanding of the characteristics of the livelihood of communities in the Liptako-Gourma region. This region, known for the tri-border area, has become the epicenter of the conflict since 2015. The study employs the Sustainable Livelihood Approach to guide survey results, as well as a focus group discussion. The results of the survey are analyzed to assess the linkage between climate-induced risks and development challenges in the region. Furthermore, the paper explores the interactions between climatic stresses and conflict risk. By taking the Liptako-Gourma region (Mali, Niger, and Burkina Faso) as a focal study and analyzing the factors impacting the livelihoods of people in the region, a survey was conducted. It included questions related to agriculture, animal husbandry, and natural resource management, among other things. The survey had seven sections and was conducted with 287 people aged between 25 to 77 years from Bagawa and Tin-Akoff. Climate perceptions were evaluated through individual and group interviews. The result from the cohort study showed a close association between security and developmental challenges in the Liptako-Gourma region. This is due to the region’s reliance on agriculture and animal husbandry, which involves frequent migration and population movement across the borders. Furthermore, the study revealed that (1) climate-induced shocks are increasingly manifested, (2) the adaptive capacity to weather climate shock remains low, (3) mobility and migration is a common strategy, and (4) the conflict over the usage of natural resources exists; however, it is not the primary cause of conflicts. Full article

The albedo of surfaces in urban areas plays an important role in regulating the urban microclimate and needs to be measured. Artificial urban surfaces, e.g., pavements with lower albedo than natural surfaces such as grass or soil, are a key contributor to the Urban Heat Island (UHI) effect. However, widespread measurement of pavement albedo in the field remains challenging due to limited available daylight hours to record the measurements, the need for clear sky conditions, and slow data collection speed. A new portable system called Discrete SPectrAl RefleCtometer (D-SPARC) was developed to overcome these difficulties. D-SPARC was calibrated in the lab using 25 concrete specimens of known albedo and found to be accurate to within ±0.05, which is similar or better than recently developed aerial or satellite methods. The calibrated D-SPARC device was then used to acquire measurements on ten pavement sections during both the day and night and compared to the results from an albedometer. The RMSE during the day was 0.06 and during the night was 0.02. Each measurement with D-SPARC took about 4 min per test location as compared to 15 min with the albedometer. D-SPARC can be used to conveniently and rapidly measure pavement albedo over a road network with reasonable accuracy and minimal traffic disruption. Full article

The water vapour column density or vertically integrated water vapour (IWV) ranges from about 8 mm in winter to about 25 mm in summer in Bern, Switzerland. However, there can be day episodes when IWV drops to 2 mm or even less so that the atmosphere is extremely dry. We selected an event in February 2021 when the tropospheric water radiometer TROWARA measured a mean IWV value of about 1.5 ± 0.2 mm for a time interval of about one day in Bern. The ECMWF reanalysis ERA5 indicated a slightly higher IWV value of about 2.2 ± 0.4 mm where the uncertainty is the standard deviation of IWV during the time of IWV depression. The ERA5 profiles of relative humidity and specific humidity during this episode are reduced by 50% and more compared to the monthly mean profiles. On a global map, it can be seen that Bern is within a mesoscale dry region on that day with descending wind. Back trajectory analysis gives the result that the dry air masses in Bern came from the North and the trajectories are descending in altitude so that dry air from the mid troposphere came into the lower troposphere. These descending air masses from the North explain the minimum of IWV observed in Bern on 13–14 February 2021. The surface climate in Switzerland was dominated by a cold wave at that time. At the same time, severe cold waves occurred in Greece and Northern America. Full article

By expressing radiative forcing (RF) in a symbolic mega-unit we better communicate, to governing organizations and the public, the extent of global warming (GW) and the potency of mitigation methods while also ‘translating’ different GW measures to better explain their interrelationship. An easily visualized symbol that has been suggested is the net shading, or mega-unit, of RF of a “standard 1 km² cumulus cloud over one day of −25 W/m²” (ScCd). As defined, ScCd is equal to 600,000 kWh and equivalent to Temporary heat radiation Equivalent Carbon (ThrEC) of 18,400 tons of carbon heat effect, or 67,300 tons of CO₂ and an approximately 0.136 albedo increase, over 1 km². Shading over the whole earth caused by clouds is estimated by NASA as −13 W/m². The excess of solar radiation or Earth Energy Imbalance (EEI) striking the earth was + 1.12 W/m² in mid-2019 and has been continually increasing. Offsetting this requires the creation of additional reflective surfaces equivalent to 22.848 million square kilometers of ScCd. Such an increase could be provided by albedo enhancement from algae on the ocean surface, marine cloud brightening (MCB) or new marine cloud creation, or land area use that rejuvenates salt flats and similar locations (AEfACL). These are potentially politically acceptable and eventually could be achieved at large enough scale to be effective globally. Full article

The climate variability associated with the ENSO phenomenon has a significant impact on wetlands, affecting the total precipitation input and hydrological flows of these ecosystems. The objective of this paper is to study the trophic status variation of an urban tropical wetland under ENSO conditions, through dynamic modeling. The results suggest an increase in precipitation, by 3.32 times, during the La Niña phase compared to the El Niño phase. Wetland input total phosphorus (TP) concentrations are 1.85 times lower during La Niña. This is probably due to a dilution effect exerted by the increase in surface runoff volumes from the basin. The findings suggest a reduction in wetland hydraulic retention time (HRT) during La Niña (1.33 times) compared to El Niño. This trend causes the TP concentration inside the wetland to decrease, possibly due to an increase in the water volume stored (dilution), and by the exit of this nutrient due to a shorter hydraulic renewal (HRT/La Niña < HRT/El Niño). The occurrence of a high input of TP concentration to the wetland does not necessarily indicate a high trophic status index (TSI). This is because the trophic status of the wetland is possibly more associated with HRT rather than input TP concentration. The trophic status of the wetland during the La Niña tends to be eutrophic. Lastly, under ENSO scenarios, the use of Aizaki’s method is suggested, because it considers HRT as a decisive factor for the calculation of wetland trophic status. Full article

Drought is one of the most challenging disasters that impact the natural and cultural ecosystems across the world, especially in the climate dependent sectors of arid and semi-arid areas. The aim of this article is to share the experiences gained and enhance the readers’ awareness on the status of drought and process of the early warning systems (EWS) in south India. Drought status of three agroecologically different states is included in this article, such as Kerala, Tamil Nadu and Telangana. As far as Tamil Nadu is concerned, Karur, Thuthukudi, Krishnagiri, Namakkal, Trichy and Thirunelveli districts are water scarce compared to other districts in the state. The districts such as Wayanad, Thiruvananthapuram, Idukki and Palakkad in Kerala have received lesser rainfall compared to the other parts of the state during the period 1981 to 2019. In Telangana, the mandals such as Nagarkurnool, Jogulamba-Gadwal, Wanaparthy, Mahabubnagar Nalgonda and Yedadri are frequently hit by dry spells and droughts. As a case study, weather early warning dissemination, carried out at Parambikulam Aliyar basin, Coimbatore, Tamil Nadu, during Khariff and Rabi seasons, using IMDs medium and extended range forecast is also elaborated in particular in the article. As far as the accuracy of forecast is concerned, probability of false detection (false alarm rate) was found to be 0.81 for Khariff and 0.30 for Rabi season, indicating the need for better performance in the accuracy of dry spell early warning, disaster preparedness and response. In-spite of this, access to early warning has supported the farmers during harvest and land preparation with a utility score of 72% and 59%, respectively. In Parambikulam Aliyar basin, remote sensing products such as MODIS-NDVI, NDWI and TWI was also used to identify the real-time progression of monthly vegetative condition for Kharif and Rabi seasons. NDVI values were used to monitor the district level vegetation condition and compared it with the drought year 2016, the difference in area under barren land was 76% less during Khariff, 2021 and 44% during Rabi, 2021.This study is a compilation of lessons learned from different states and the existing knowledge and practice in early warnings, and recommends the need for a holistic approach in drought and dry spell monitoring along with better accuracy and dissemination to minimize climate-related shocks in agriculture. Full article

Every year, cut-off low (COL) pressure systems produce severe weather conditions and heavy rainfall, often leading to flooding, devastation and disruption of socio-economic activities in South Africa. COLs are defined as cold-cored synoptic-scale mid-tropospheric low-pressure systems which occur in the mid-latitudes and cause persistent heavy rainfall. As they occur throughout the year, these weather systems are important rainfall producing systems that are also associated with extreme cold conditions and snowfalls. An in-depth review of COLs is critical due to their high impacts which affect some parts of the country regularly, affecting lives and livelihoods. Here, we provide a comprehensive review of the literature on COLs over the South African domain, whilst also comparing them with their Southern Hemisphere counterparts occurring in South America and Australia. We focus on the occurrence, development, propagation, dynamical processes and impacts of COLs on society and the environment. We also seek to understand stratospheric–tropospheric exchanges resulting from tropopause folding during the occurrence of COLs. Sometimes, COLs may extend to the surface, creating conditions conducive to extreme rainfall and high floods over South Africa, especially when impinged on the coastal escarpment. The slow propagation of COLs appears to be largely modulated by a quasi-stationary high-pressure system downstream acting as a blocking system. We also reviewed two severe COL events that occurred over the south and east coasts and found that in both cases, interactions of the low-level flow with the escarpment enhanced lifting and deep convection. It was also determined from the literature that several numerical weather prediction models struggle with placement and amounts of rainfall associated with COLs, both near the coast and on the interior plateau. Our study provides the single most comprehensive treatise that deals with COL characteristics affecting the South African domain. Full article

Compound weather and climate extremes have amplified impacts on natural and socioeconomic systems across the world, including Singapore. To better understand the spatial and temporal characteristics of compound climate extremes, including concurrent rainfall and wind speed, as well as dry and hot conditions, we analyzed long-term observations from 11 selected meteorological stations over the period 1985–2020. The results revealed that the north and northeastern parts of Singapore were focal points for both types of compound extremes, with a higher frequency of occurrence than the southwest of the island. Concurrent rainfall and wind speed extremes were the most prominent in December and January thanks to the northeast monsoon, while dry and hot extremes were distributed mainly in the inter-monsoon season, with peaks in March and April. A notable upward trend was also detected for mild and moderate levels of both compound climate extremes over time. According to our review of the impacts, Singapore has benefited from investments in enhanced water infrastructure; water resource availability was less affected; and flash floods were not proportionally related to the severity of climate extremes. The forests in the urban landscape of Singapore also exhibit resilience to drought. Full article