The indicator is an impact indicator and expresses the annual change in sea surface temperature.

The main source of weather events and air masses in the atmosphere are the oceans and seas. The most accurate indicator of climate change is the warming and cooling of the sea surface. Warming or cooling of the sea surface affects many living organisms by changing the ecological structure of the oceans, and it is closely linked to an important group that benefits economically from the oceans.

Sea surface temperature is a meteorological parameter that is not directly affected by atmospheric warming and cooling, as is the case with air temperature. In addition, the sea warms more slowly than the land and cools more slowly, so its temperature does not change so suddenly during the day. The main factors affecting sea surface temperature are latitude, salinity, cold water currents, and the wind direction that prevails during the day.

According to data from the Turkish State Meteorological Service, although there has been a slight increase in mean sea surface temperatures in Turkey for many years, there can be no talk of global warming yet. The Turkish State Meteorological Service is continuing its studies to measure sea surface temperature on all our coasts and seas to monitor this process. This will provide a higher resolution data source on our seas.

Mean sea surface temperatures in 2020 were 22.2 °C in the Mediterranean Sea, 19.2 °C in the Aegean Sea, 18.0 °C in the Sea of Marmara, and 16.3 °C in the Black Sea. The charts below show the annual mean sea surface temperatures (°C) measured in the seas between 1970 and 2020.^[27].

GRAFİK 19- ANNUAL MEAN SEA SURFACE TEMPERATURES MEASURED IN THE MEDITERRANEAN SEA(°C)

GRAPH 20- ANNUAL MEAN SEA SURFACE TEMPERATURES IN THE AEGEAN SEA (°C)

GRAPH 21- ANNUAL MEAN SEA SURFACE TEMPERATURES IN THE BLACK SEA (°C)

GRAPH 22- ANNUAL MEAN SEA SURFACE TEMPERATURES IN THE SEA OF MARMARA (°C)

Source: The Ministry of Environment, Urbanisation and Climate Change, Turkish State Meteorological Service; 2021