Bottlenose and other Dolphins are a rare Sight in the Eastern Mediterranean
On my to-do-list for this year’s trip is a blog on the weather and sea temperature in the eastern Mediterranean. Turns out there is little to say. Water is on average 23 to 24 degrees, it is always sunny and temperature in the mid to high thirties.
The Salinity in the Eastern Mediterranean is a good 15% higher than in the West
A more interesting story though is the high salinity of the eastern Mediterranean. It reaches almost 0.40% whilst it’s only 0.35% in the Straits of Gibraltar. The high salinity results from above average evaporation. Even the inflow of fresh water from the Nile and low salinity sea water from the Black Sea cannot compensate for the loss. You notice the elevated salinity instantly when swimming in the sea. Buoyancy is higher than usual. Floating is effortless. No wonder the beaches in southern Anatolia are so popular.
Buoyancy is not the only effect high salinity has. The high salt content also affects aquatic life. There is far less plankton than in the Black Sea, the Aegean, the Adriatic or the Cote d’Azur. There are no big rivers rich in silt and minerals – the food for plankton - flowing into the eastern Mediterranean. The Nile once rich in silts is now dammed in Aswan. Constructed between 1960 and 1970, the Aswan dam retains the silt from Ethiopia's mountains and deprives the sea of nutrients. With little plankton to feed on, there are fewer fish in the eastern Med than in the western part. Few fish = few dolphins. We definitely won’t see as many as we encountered on the way from Corsica to Sicily in 2020. I now also understand why there is so little professional fishing on Turkey’s south coast. Not enough fish!
Map showing the Frequency of Spotting Stripe Dolphins in the Mediterranean
The salinity in the eastern basin was not always constant though. Research on sea sediments indicate that it was lower between 20’000 and 8’000 BC, when global temperatures increased and the world’s ice sheets started to melt. The melt water from the Siberian Glaciers could not escape north thus flowed south towards the Aral, the Caspian and the Black Sea. These waters are salty today but at the time were giant fresh water lakes as we know them from North America. The fresh water eventually dug the Bosporus Valley when it spilt over the low land bridge between Europe and Asia. Thus, all the Siberian melt water ended up in the Aegean from where it flowed into the eastern Mediterranean.
The Aral, Caspian and Black Sea were giant fresh Water Lakes at the End of the Ice Age
Salinity during these “spill over” years dropped substantially. We all know that fresh water evaporates easier than salt water. It requires less energy. There is no hydrochloric acid to break that forms from the combination of water and salt. The eastern Mediterranean must thus have had an even higher evaporation ratio from 20’000 to 8’000 BC. As a result, levels of humidity and precipitations in the Fertile Crescent were higher than what we see today.
The Fertile Crescent where the Agricultural Revolution started
Already talked about Turkey’s high level of biodiversity which is a function of its geology and geography. Many early settlement or religious centers like Göbekli Tepe (10’000 years old) or Boncuklu Tarla (11’300 years old) are located in semi-arid regions on the border of Turkey and Iraq. These places were humid and enjoyed good water supply in the past.
I guess that the melting of the Siberian glaciers and the subsequent flow of huge quantities of fresh water into the Mediterranean created the pre-conditions for the rapid diversification of plants in the Fertile Crescent which eventually led to the agricultural revolution. The idea that climate change triggered the agricultural revolution should make us reconsider the doomsday narrative that dominates today’s climate discussions. A warmer and more humid world was definitely beneficial for human beings.
During the Ice Age Zurich and Geneva were covered by 1'000 meter thick glaciers
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