Vol 114, No 2 (2022): THEMED SECTION: UNITED NATIONS DECADE OF OCEAN SCIENCES FOR SUSTAINABLE DEVELOPMENT (2021 to 2030)

The United Nations Decade of Ocean Science for Sustainable Development (2021–2030) was proclaimed by the UN General Assembly in 2017 on the initiative of the Intergovernmental Oceanographic Commission of UNESCO and entered the implementation phase from January 2021. The main watchword of the Decade is “The Science We Need for the Ocean We Want”. It is based on seven socially significant outcomes. To achieve them, ten priority challenges have been identified. These challenges are divided into three groups: Knowledge and Solutions Challenges, Essential Infrastructure Challenges and Foundational Challenges. Although the Decade Implementation Plan considers Ocean Sciences in its broadest sense, including the nature sciences and social sciences and humanities, local and indigenous knowledge, science-policy and science-innovation interactions, and technology and infrastructure etc., basic oceanographic research are of paramount importance for understanding and achieving virtually all seven Decade Outcomes.

This paper provides a brief overview of the state of research on the Global Ocean Conveyor Belt (GOCB) as an element of the Global Ocean Circulation linking the thermocline and the abyssal. In particular, it is noted that the existence of GOCB cannot be due only to the action of thermohaline factors. In addition to them, a wind effect on the Ocean is also necessary. Moreover, the area of such impact, which determines the very configuration of the GOCB, is the Southern Ocean. In addition, for the very existence of the GOCB in its current form, the configuration of the continents of the current geological epoch is of fundamental importance.

The paper deals with global changes in regime and climate of Arctic basin. Changes in the content and inflows of freshwater into the upper 100 m layer of the Arctic basin from decade to decade (1950s – 2010s) were determined. Data from national expedition surveys of the Arctic Basin in the 1950s to the 1970s combined with data from expeditions in the 1980s to the 2010s were used. The results obtained showed that freshwater content (FWC) decreased in the Eurasian and increased in the Amerasian part of the Arctic basin in the 1990s – 2000s. The decrease in the FWC occurred in the result of increased Atlantic water inflow since the 1990s and the salinization of the upper 100 m layer of Arctic Ocean, despite increased precipitation, river runoff and sea ice melt. The influence from the tropics of the North Atlantic on climatic changes in the structure of Arctic basin waters, on the reduction of the sea ice cover and warming in the Arctic with a delay of 2-3 years was established. Methods of multidimensional correlation analysis, calculation of spectra and coherences, and construction of correlation graphs were used.

The presented article is devoted to the results of detailed studies of the features of extreme sea level fluctuations in the Russian Arctic under the conditions of global climate change. Estimates of the rate of mean sea level rise in the Arctic are obtained from the monthly mean sea level data at coastal tide gauges and satellite altimetry. It was found that for the Arctic Ocean coast from the Kara to the Chukchi Seas, the highest tides take place in the Khatanga Bay (Preobrazheniya Island), 131 cm. In the White, Kara, Laptev and Chukchi Seas, the seasonal variability of harmonic tidal constants was studied; it occurs due to changes in hydrometeorological conditions during the year. The ADCIRC hydrodynamic model was adapted for the conditions of the Laptev Sea. Numerical modeling of sea level oscillations from 1980 to 2000 was performed. According to the simulation results, the maximum ranges of residual sea level fluctuations are observed both for the total level and at the mouth of the Khatanga (489 cm) and Oleneksky Bay (444 cm). Based on the data of coastal observations and numerical modeling, the authors obtained estimates of extreme level fluctuations with different recurrence periods.

Based on the analysis of data from long-term radioecological observations in the Barents Sea, the main migration flows of ¹³⁷Cs and ⁹⁰Sr in its ecosystem have been reconstructed. In the current (2010–2019) balance of technogenic radioactivity, the transboundary transfer of radioisotopes from the Norwegian Sea accounts for more than 90% of the total intake. Most of the incoming radionuclides are removed from the Barents Sea through its northern and northeastern borders in the process of water exchange. A significant decrease in the concentrations of radionuclides in the components of the environment and biota in the “post-nuclear era” is shown. The content of ¹³⁷Cs and ⁹⁰Sr in the food web of the marine ecosystem was estimated in comparison with the reserve of their activity in water and bottom sediments. The biotas accumulate no more than 0.01% of the total isotope content in the ecosystem.