^{Image: Vastram/Shutterstock}

Back in the early 1990s, the pedestrian seaside boulevard in the centre of Baku stood by and large under water. Attempts to protect it from the rising Caspian Sea by building a concrete barrier appeared likely fail. Further to the south in the Talysh regions were even more unlucky as entire strings of shore-side houses were flooded. The cause was a dramatic change in the Caspian Seal rising from 29m below mean sea level in1978 to reach a peak of -26.5m in 1995. 

A report by the Taskent-based Eurasian Research Institute estimates that 400,000 hectares of coastal areas were affected during this period. In Azerbaijan alone, it suggests “over 50 settlements, 250 industrial enterprises, 20 km of railways, 60 km of highways, and recreational facilities for 100,000 people experienced floods” with an estimated economic damage of some US$2 billion. 

The result was that littoral states started seeing flooding as a key hazard. However, since 1995 the Caspian has been sinking again and is now down to a level of -28m. And the end does not seem to be in sight. Now, global warming warriors have joined a chorus of reports predicting a further drop to well below -30m, much to the detriment of the region’s maritime fauna and flora. 

When Continents and Oceans Came and Went

The story goes back to the very origins of the Caspian Sea and the lands bordering it. For around 200 million years during a period that ended with the Precambrian Age (around 500 million years ago,) (or roughly 2 billion years after the formation of the earth – that makes no sense as it would make the earth only 2.7 billion years old. Normally 4.5 is closer to the accepted figure) the present-day Caspian depression was on the outskirts of the mega-continent of Rodinia – one of the first split-offs of the land mass on the planet‘s southern hemisphere into the water-covered north.

In the middle of the Devonian Period (around 300 million years ago), a depression started to develop stretching from the location of today’s Aral Sea ever further to the west, leading to the formation of the Paleo-Tethys Ocean to the west. The Central-Kazakh plateau sat on its eastern shore, Baltica to its north and it reached as far as Gondwana towards the southwest. 

(Before this add some more detail – Pangea is breaking up without being introduced) When in the Jurassic Period around 180 million years ago Pangea started to disintegrate, the Paleo-Tethys Ocean retreated to the west, which in turn led to the formation of the Tethys trench and the ocean of the same name.

The Caspian Sea and its Outlets to Open Waters

When the first proto-human in the region at some point between two and one million years ago, the Tethys Ocean of old was not entirely dead yet, and the proto-Caspian Sea, which included the Aral Sea and the lands between them was still "oceanic" enough to allow large areas to its east and its south to sustain subtropical conditions. At this stage it still had open waterways to the north and the west. It was only in the course of the II Millennium BC that the open waterway towards the north was closed, and the opening towards the Black Sea was still intact at the time of Alexander the Great in the 4^th Century BC. 

Biblical sources tell that, two centuries earlier, the Philistinian sea-faring king Hiram sailed to the southeast Caspian shore and from there carried on by caravan to the borderlands between present-day Uzbekistan and Kyrgyzstan to collect gold from the mines located there in order to sell it to his friend and ally king Solomon of Israel. So, assuming the tale has a historical basis, one must conclude that the Manych Strait (This term was not introduced – do you mean the Western opening that you mentioned above?) was still navigable. For all it matters, some claim that Solomon came to the premises himself and built a temple in the present-day town of Osh, remains of which still exist.

Retrospective Scientific Calculations

According to geologists, surges in the Caspian Sea level occurred about a million years ago in the Tyurkyanian age, 600,000 years later in the Singilian era, and again 200,000 years after that in the Kazarian epoch. From 100,000 years before our time, extreme surges became more frequent and occurred during the Atelian, Enotevkayan and Mangyshlakian periods – the latter ending around 6,000 years ago. 

Whereas thus far Caspian Sea fluctuations are based on retrospective scientific calculations, serious contemporary monitoring of the sea surface level only started in the 1840s, after imperial Russia had consolidated its authority over most of the Caspian region, allowing scientists to do their work unhindered. 

The work was continued into Soviet times, but scientists remained unable to explain the phenomenon of the Caspian’s Sea level changes which differ completely from oceanic level oscillations. However, for about a century, the Caspian oscillations appeared relatively minor, never more than a metre more or less than -26m.

^{Image: CATENA Volume 166, July 2018, Pages 339-348}

Emissions Scenarios Come on Board

This was to change abruptly in the course of the 1930s, when the sea level plunged, reaching 28m below ocean level as of 1940. After that the dive continued at a slower pace, before hitting 1978’s minimum of -29m and rebounding as we have mentioned, until the 1995 peak only to tumble again. 

How this could end no one knows. There is still no scientific consensus as to the processes in action but those who venture into the realm of predictions offer a gloomy outlook.

(There were again long quotes in this paragraph, it has been fixed but please write in this style going forward, without long quotes) A 2020 report in the respected journal Nature projects a further fall of 9–18m caused by an imbalance between lake evaporation and river discharge/precipitation on the assumption that the global system continues a scenario of “medium to high [greenhouse gas] emissions” until the end of this century. That’s about twice as much as predicted by estimates based on earlier climate models. The result of such a catastrophic fall would be that the vast northern Caspian shelf along with the Turkmen shelf in the southeast, and all coastal areas in the middle and southern Caspian Sea would be left above water. In addition, the Kara-Bogaz-Gol Bay on the eastern margin would be completely desiccated. Overall, the report warns, “the Caspian Sea’s surface area will shrink by 23% for a 9 m and by 34% for an 18 m drop of sea level.”

Humanity failed to save the Aral Sea. Whether stringent attempts to cut greenhouse gasses can save the Caspian remains to be seen.