Climate Change Hypothesis

Today, most Russian scientists believe that climatic factors are the real cause of the Caspian Sea level rise. Studies by Golitsyn (1989) and Golitsyn and McBean (1992) indicate that recent changes of the Caspian Sea level are 90% associated with corresponding changes in the water balance components of the sea, as opposed to possible tectonic activity. The volume of inflow from rivers to the sea increased sharply after 1978. During certain years (e.g., 1979, 1985, and 1990), more than 350 km3 of river water entered the sea. From 1978 until 1990, Volga River flow exceeded 260km3/yr. At present, no arguments have challenged the view that the main contribution to seasonal and annual level fluctuations of the Caspian is accounted for by surface inflow and evaporation levels. Within recent decades, the sea's fluctuations have been subjected to anthropogenic impacts as well.

In this regard, climate has two dimensions: climate fluctuations and climate change. Climate fluctuations occur on various time scales, with those of interest to present-day society being on the order of decades and perhaps centuries. Climate-related fluctuation refers to the increase and decrease of sea level over the course of decades. During the past two centuries, the sea has undergone several fluctuations. Those of the twentieth century have adversely affected socioeconomic activities and infrastructure along the sea's coastline.

The view that climatic processes in the Volga basin are the dominant cause of sea-level fluctuations has been recently reinforced. Droughts in this basin and sharply reduced Volga flow into the Caspian from mid-1995 until early 1997 have been associated with a 25-cm (10-inch) drop in Caspian level. Nevertheless, Russian scientists still suggest that the sea level will continue to rise into the first decades of the twenty-first century.

Climate change associated with global warming induced by human activities has also been proposed as the forcing factor behind the Caspian's rise since 1978. Those who see global warming as the forcing factor suggest that the most recent sea-level rise can be associated with intensification of the hydrologic cycle (i.e., more active precipitation-producing processes), an intensification that some scientists have linked to the human-induced global warming of the atmosphere. An increase in precipitation within the Volga River basin would translate into increased sea level.

Was this article helpful?

0 0

Post a comment