The water temperatures are mild in winter and warm in summer and give name to the Mediterranean climate type due to the majority of precipitation falling in the cooler months.

This term (literally "great green") was the name given by the Ancient Egyptians to the semi-solid, semi-aquatic region characterised by papyrus forests to the north of the cultivated Nile delta, and, by extension, the sea beyond.

[93] Over the course of the last 44 million years, the continental plates of Africa and Eurasia have converged and receded, resulting in the current tectonically active basin and its surrounding mountain chains.

According to the interpretation of geologic data, there are currently several major places where Africa and Eurasia collide, causing land submergence, mountain building, and volcanism.

[82] Sediment cores drilled in 1970 and 1975 led to theories that about 6 million years ago, the Mediterranean was around 3,000 metres (10,000 ft) below the current sea level and included arid deserts blanketed with evaporite salts.

These waters have different physical and chemical characteristics, and the periodic inversion of the North Ionian Gyre (called Bimodal Oscillating System or BiOS) changes the Mediterranean circulation and biogeochemistry around the Adriatic and Levantine regions.

Human-induced climate change appears to play a growing role in the development of marine heatwaves that have become a prominent subject of research in recent years, particularly in the Mediterranean where a number of areas in both western and eastern sub-basins now experience peaks of temperatures, along with more frequent, more intense, more prolonged warming events than ever seen on record.

These events, mainly driven by a combination of oceanic and atmospheric factors, are often triggered by high pressure systems that will reduce cloud cover and increase solar absorption by the sea surface.

Their impacts on marine ecosystems, such as mass mortality in benthic communities, coral bleaching events, disruptions in fishery catches and shifts in species distributions, can be devastating.

High (i.e. more than 0.5 grams of Chlorophyll a per cubic meter) productivity occurs in coastal areas, close to the river mouths which are the primary suppliers of dissolved nutrients.

In winter, the strong winds and precipitation over the basin generate vertical mixing, bringing nutrients from the deep waters to the surface, where phytoplankton can convert it into biomass.

[120][118] Oceanographic expeditions uncovered a characteristic feature of the Mediterranean Sea biogeochemistry: most of the chlorophyll production does not occur on the surface, but in sub-surface waters between 80 and 200 meters deep.

Water poured in from the Atlantic Ocean through a newly breached gateway now called the Strait of Gibraltar at an estimated rate of about three orders of magnitude (one thousand times) larger than the current flow of the Amazon River.

At about that time in the middle Jurassic period (roughly 170 million years ago [dubious – discuss]) a much smaller sea basin, dubbed the Neotethys, was formed shortly before the Tethys Ocean closed at its western (Arabian) end.

The Neotethys grew larger during the episodes of collisions (and associated foldings and subductions) that occurred during the Oligocene and Miocene epochs (34 to 5.33 mya); see animation: Africa-Arabia colliding with Eurasia.

This event was for long the subject of acute scientific controversy, now much appeased,[133] regarding its sequence, geographic range, processes leading to evaporite facies and salt deposits.

In 2003, the World Wildlife Fund raised concerns about the widespread drift net fishing endangering populations of dolphins, turtles, and other marine animals such as the spiny squat lobster.

Based on a broad variety of methods, e.g. historical documents, analysis of trade relations, floodplain sediments, pollen, tree-ring and further archaeometric analyses and population studies, Alfred Thomas Grove's and Oliver Rackham's work on "The Nature of Mediterranean Europe" challenges this common wisdom of a Mediterranean Europe as a "Lost Eden", a formerly fertile and forested region, that had been progressively degraded and desertified by human mismanagement.

[145] The belief stems more from the failure of the recent landscape to measure up to the imaginary past of the classics as idealised by artists, poets and scientists of the early modern Enlightenment.

Also, the climate has usually been unstable and there is evidence of various ancient and modern "Little Ice Ages",[146][page needed] and plant cover accommodated to various extremes and became resilient to various patterns of human activity.

[145] Among further current important threats to Mediterranean landscapes are overdevelopment of coastal areas, abandonment of mountains and, as mentioned, the loss of variety via the reduction of traditional agricultural occupations.

The geology of the region, with the presence of plate boundaries and active faults, makes it prone to quite frequent earthquakes, tsunamis and submarine landslides with can have devastating consequences in densely populated coastal areas.

One of the most destructive was the Crete earthquake in 365 BC, with Mw > 8, which lifted the western tip of the island by up to 9 m and caused a mega tsunami that destroyed many harbors in the eastern sub-basin.

In many cases this reflects an expansion – favoured by a warming trend of sub-tropical Atlantic waters, and also by a fast-growing maritime traffic – of the natural range of species that now enter the Mediterranean through the Strait of Gibraltar.

A 1994 study of the seabed using trawl nets around the coasts of Spain, France and Italy reported a particularly high mean concentration of debris; an average of 1,935 items per km2 (5,010/sq mi).

In particular, the Maritime Silk Road from Asia and Africa leads through the Suez Canal directly into the Mediterranean Sea to its deep-water ports in Valencia, Piraeus, Trieste, Genoa, Marseille and Barcelona.

An important destination is the Port of Trieste, the starting point of the Transalpine Pipeline, which covers 40% of Germany's oil demand (100% of the federal states of Bavaria and Baden-Württemberg), 90% of Austria and 50% of the Czech Republic.

Tourism often concentrates in areas of high natural wealth[clarification needed], causing a serious threat to the habitats of endangered species such as sea turtles and monk seals.

The European Environment Agency says that more than 65% of all fish stocks in the region are outside safe biological limits and the United Nations Food and Agriculture Organisation, that some of the most important fisheries—such as albacore and bluefin tuna, hake, marlin, swordfish, red mullet and sea bream—are threatened.

In 1999, Greenpeace published a report revealing that the amount of bluefin tuna in the Mediterranean had decreased by over 80% in the previous 20 years and government scientists warn that without immediate action the stock will collapse.