St Petersburg University oceanographer speaks on Heinrich Terahertz podcast about humanity’s impact on the World Ocean
The guest of the third series of the second season of the popular science podcast "Heinrich Terahertz" was Polina Lobanova, Doctor of Geography, lecturer of the Russian Society "Znanie" ("Knowledge"), and Associate Professor at St Petersburg University. She spoke about the mysteries of the World Ocean—a unique natural mechanism that both sustains the delicate balance of life on Earth and faces serious environmental challenges.
The ocean covers 70% of the planet’s surface, with an average depth of about four kilometres, which is significantly greater than the average height of the continents, which barely reaches 900 metres. Even Antarctica rises, on average, to just two kilometres. Not only is the water column vast, it is also incredibly deep.
According to one hypothesis, the Earth was once completely covered by an ocean that appeared around four billion years ago and underwent significant evolutionary changes. A key turning point was the emergence of photosynthetic bacteria capable of producing oxygen. These organisms altered the composition of the atmosphere, creating conditions necessary for the development of complex life forms.
Polina Lobanova, Associate Professor at St Petersburg University, was among the winners of the All-Russian competition "Znanie. Lecturer" and received a special prize — a river cruise with the opportunity to deliver lectures on board.
According to Polina Lobanova, the planet’s primordial ocean was likely acidic due to high concentrations of carbon dioxide resulting from intense volcanic activity. The early ocean was rich in chloride and iron compounds, the dissociation of which over time contributed to the current salinity levels of the oceans.
Today, most of the hydrosphere is a weakly alkaline buffer system that maintains a relatively stable pH level while absorbing a significant portion of the carbon dioxide produced by increasing anthropogenic activity. The problem with this rising CO₂ concentration is that the aquatic environment is gradually becoming acidic once more, dissolving calcium carbonate — an essential material for the formation of coral skeletons and phytoplankton shells. According to Polina Lobanova, coral reefs, which play a crucial role in the marine ecosystem, have suffered significant degradation in recent decades.
The ocean is indispensable: every fifth breath we take is thanks to oxygen produced by microalgae in tropical regions. Moreover, many countries rely on seafood derived from phytoplankton, the foundation of the marine food chain.
Polina Lobanova, Doctor of Geography, lecturer of the Russian Society "Znanie" ("Knowledge"), and Associate Professor at St Petersburg University
"Additionally, the ocean acts as a climate regulator, influencing temperature and weather conditions. For example, the warm Gulf Stream prevents the port of Murmansk, north of St Petersburg, from freezing," Polina Lobanova noted.
Despite the serious challenges it faces, the history of the ocean demonstrates its remarkable capacity for recovery. Understanding the mechanisms that led to the Great Oxygenation Event two and a half billion years ago may play a key role in developing strategies to mitigate the effects of acidification.
Online courses supervised by Polina Lobanova are the following:
"While it is impossible to eliminate production entirely, everyone can contribute to protecting the ocean — for example, by conserving water and reducing emissions. The period from 2021 to 2030 has been proclaimed the Decade of Ocean Science for Sustainable Development by the United Nations, with the aim of ensuring that the ocean becomes clean, healthy, productive, and predictable," noted Polina Lobanova, an oceanographer from St Petersburg University.