The study of the dynamics of sea level in the Cenozoic confirmed the role of man in its modern increase

Fluctuations of sea level throughout the Cenozoic era (the last 66 million years) largely depended on the parameters of the earth’s orbit than the concentration of CO2 in the atmosphere. In an article published in the journal Science Advances, indicate the episodes of rising and falling sea level in accordance with the periods of solar-lunar precession, oscillations of the orbital eccentricity and the tilt of the earth axis. But since the XX century the decisive role in sea level change have moved to the anthropogenic emissions of greenhouse gases.

The sea level rise is one of the most obvious manifestations of global climate change. The rate of this process increased from 1.4 millimeters per year in the twentieth century to 3.1 ± 0.4 mm per year in the early twenty-first century. Scientists link this with human activities, but face more objections: after all, the sea level rise is affected by a large number of geological processes, and leading role of anthropogenic climate change is not so easy to prove. For example, some existing studies of sea-level changes in the Cenozoic pointed to the crucial role of Milankovitch cycles in the process.

Scientists led by Kenneth Miller (Kenneth G. Miller) from Rutgers University researched the history of sea level changes over the past 66 million years, covering the whole Cenozoic era until 2010. To do this, they studied deposits of fossilized foraminifera Cibicidoides spp. on the continental shelf of new Jersey and Delaware, thanks to new research avoid artifacts in the form of a link the Atlantic and Pacific oceans, which was accompanied by a classic publication in this field.

The concentration of heavy 18O, fixed in the shells of foraminifera in the process of calcification, increases with decreasing water temperature, and this feature can be used for paleoclimatic analysis. The authors of the study adhered to the following calibration scales: the concentration of 18O in water under 0.5 ppm, which indicates the period of global warming; 0.5 — 1.8 ppm — period of temperate climate; more than 1.8 ppm — glacial period.

Leave a Reply

Your email address will not be published.