Time-frequency dependency of temperature and sea level: a global perspective

The importance of environmental sustainability to all human aspects has been spiking as the world keeps evolving. Economies around the world are on the move to ensure sustainable economic development and a clean atmosphere through the use of renewable energy sources. Since the end of the nineteenth century, it is recognized that a global mean sea level rise speed about 1.7 ± 0.2 mm/year, but the rate has increased to 3.2 ± 0.4 mm/year. In this study, we investigated the dynamic linkage between average temperature and sea level within the global framework covering 1881 to 2013. The paper employs wavelet analysis to investigate the short-term and long-run causal links between global average temperature anomalies and global sea level. In this respect, our findings indicate that (i) a significant vulnerability in global average temperature and sea level is observed over the selected study period; (ii) global average temperature has considerable power for predicting sea level, particularly in the long-term. The causality test revealed a bi-directional causal relationship between global average temperature and sea level and unidirectional flow from global average temperature to sea level. And the study confirms the "conservation hypothesis," and it has long-run implications for environmental quality. Thus, minimizing global average temperature anomalies is a decisive ingredient for minimizing sea level rise. Based on these outcomes, both developed and developing countries' policymakers should support the Paris agreement (COP21) agreement to control CO₂ emissions growth. Policymakers should encourage the usage of environmentally friendly energy sources that will enhance environmental quality and hold the increase in global average temperature below 1.5 °C.

Testing the Resilience of CSR Stocks during the COVID-19 Crisis: A Transcontinental Analysis

Investors and practitioners are increasingly concerned with financial assets within the scope of corporate social responsibility (CSR) meaning that, in recent times, such assets have become enshrined in the preferences of the new generations of investors and consumers. Just when the interest of investors was at its highest, SARS-CoV-2 (COVID-19) affected all international financial markets, so that, at first sight, it might seem that the financial assets assigned to CSR should have suffered collapses that were identical to the rest; however, our work shows the opposite, providing a comparative analysis of how the pandemic has affected the financial markets of each continent to demonstrate its outstanding resilience through the use of the Wavelets methodology. We analyzed the global impact of the registered cases of COVID-19 on the Dow Jones Sustainability World Index (DJSWI), the world’s leading indicator of sustainable companies, in addition to six other financial indices selected from each continent. The empirical results of this research show that the worldwide repercussions of the sudden outbreak of SARS-CoV-2 has had a substantially smaller effect on sustainability-related indices compared to the other considered indices. Similarly, the methodology employed allowed the establishment of a chronogram with details of the dating of COVID-19 expansion through the considered countries, a certain gradation in terms of the impact of the pandemic on these stock indices, and certain common guidelines describing their devastating effects on each of the financial markets represented by the indices in this research.

Drought Frequency Analysis Based on the Development of a Two-Variate Standardized Index (Rainfall-Runoff)

Drought is one of the most drastic events, which has imposed irreparable damages on human societies and may occur in any climate regime. To define drought, given its properties of multidimensionality and randomity, one cannot rely on a single variable/index (e.g., precipitation, soil moisture, and runoff). Accordingly, implementing a novel approach, this study investigated drought events in two basins with different climatic regimes, using multivariate frequency analyses of drought duration, severity, and severity peak, based on developing a Two-variate Standardized Index (TSI). The index was developed based on the concept of copula, by applying rainfall-runoff data (1974–2019) and comparing them with two popular drought indices, the Standardized Precipitation Index (SPI) and Standardized Stream Flow Index (SSFI), in terms of derived drought characteristics. The results show that TSI determined more severe drought conditions with fewer return periods than SPI and SSFI in a specific drought event. This implies that the disadvantages of SPI and SSFI might not be found in TSI. The developed index can be employed by policymakers and planners to protect water resources from drought.

Water Level Decline in a Reservoir: Implications for Water Quality Variation and Pollution Source Identification

Continuous water-level decline makes the changes of water quality in reservoirs more complicated. This paper uses trend analyses, wavelet analysis and principal component analysis-multiple linear regression to explore the changes and pollution sources affecting water quality during a period of continuous reservoir water level decline (from 65.37 m to 54.15 m), taking the Biliuhe reservoir as an example. The results showed that the change of water level of Biliuhe reservoir has a significant 13-year periodicity. The unusual water quality changes during the low water level period were as follows: total nitrogen continued to decrease. And iron was lower than its historical level. pH, total phosphorus, and ammonia nitrogen were higher than historical levels and fluctuated seasonally. Permanganate index increased as water level decreased after initial fluctuations. Dissolved oxygen was characterized by high content in winter and relatively low content in summer. The pollutant sources of non-point source pollution (PC1), sediment and groundwater pollution (PC2), atmospheric and production & domestic sewage (PC3), other sources of pollution (PC4) were identified. The main source of DO, pH, TP, TN, NH₄-N, Fe and COD_Mn were respectively PC3 (42.13%), PC1 (47.67%), PC3 (47.62%), PC1 (29.75%), PC2 (47.01%), PC1 (56.97%) and PC2 (50%). It is concluded that the continuous decline of water level has a significant impact on the changes and pollution sources affecting water quality. Detailed experiments focusing on sediment pollution release flux, and biological action will be explored next.