Extreme Heat in Mediterranean Sea

Context

Extreme heat has plagued the Mediterranean for weeks ending with wildfires across nine countries in the region from Algeria to Greece. This increasing heat has impacted the marine life as well.

So, let us see how?

Why are high sea temperatures a problem?

Lesser dissolution of gases: Gases like oxygen and carbon dioxide dissolve better at colder temperatures, so that means the warmer the water; the less oxygen is available to breathe.
Higher rate of respiration in marine organism: Higher temperatures also cause an increase in metabolism, which in turn means animals have to breathe even more than usual.
The rise in temperature accelerates metabolism, and the organisms need more food to maintain this metabolic rate.
More Algal blooms: They are more common in hotter waters. Such blooms can further deplete oxygen levels and produce toxins harmful for fish, marine mammals and birds.

What species and ecosystems are worst hit by marine heat waves?

High water temperatures are most harmful for animals living at the bottom of oceans, lakes or rivers.
These benthic species include corals, mussels, sponges, starfish and plants like sea grasses, and are often attached to rock or solid ground.
Scientists observed mass deaths of benthic species along thousands of kilometers of Mediterranean coastline between 2015 and 2019.

What does extreme heat in the Mediterranean mean for people?

Affecting fishing activities in the area: Fishermen are catching fewer familiar species and instead are finding more invasive fish which they have difficulty selling.
Increase in invasive fishes: Some are even poisonous, like the puffer fish migration is seen in the region.
Habitat loss: It could also lead to an overall decline in fish populations, while disappearing seagrass.

What is the phenomenon behind heat trap in oceans?

Ocean Heat Content (OHC): It is the amount of energy absorbed by and stored in the oceans. It is measured in joules.
When sunlight reaches the earth, oceans absorb this energy and store it as heat.
While the heat is first absorbed at the surface of the water body, some of it is eventually disbursed throughout.
Water has a higher heat capacity than air, which means that it can store much larger amounts of heat.
GHG emissions - These gases trap heat in a blanket around the earth, not allowing it to escape, thus raising the temperature of the earth’s surface and leading to global warming.

Why Mediterranean Sea is significant for global temperatures?

The Mediterranean Sea has significant implications for global temperatures due to its role as a "climate amplifier." This phenomenon is referred to as the "Mediterranean Effect" or "Mediterranean Climate Amplification." Here are the reasons:

Heat Absorption and Release: The Mediterranean Sea has a lower heat capacity compared to the vast oceans, such as the Atlantic or Pacific.
- As a result, it heats up and cools down more quickly. During the summer months, the Mediterranean Sea absorbs heat from the sun, leading to warming of the surrounding land areas.
- In winter, it releases the stored heat, moderating temperatures in nearby regions.
Warm and Dry Summers: The Mediterranean region experiences warm and dry summers, which are conducive to high evaporation rates from the sea's surface.
- This process results in the release of latent heat into the atmosphere, contributing to the warming of the air.
Atmospheric Circulation: The temperature contrast between the relatively warm Mediterranean Sea and the cooler landmasses during summer leads to the development of low-pressure systems over land.
- This creates a pressure gradient that drives winds from the sea to the land, bringing warm, moist air with it. This warm air can further increase temperatures over land areas.
Feedback Loops: The warming effect of the Mediterranean Sea can lead to feedback loops. Warmer land areas result in higher evaporation rates, which in turn contribute to the amplification of temperature rise.
- This cycle of heat absorption, release, and evaporation intensifies the Mediterranean Climate Amplification.