The higher the sea level, the greater the risk of flooding during storms
Photo: David Hastilow / Getty Images
The state of the oceans is worrying: the combination of several problems not only threatens ecosystems and marine animals, but also has consequences for millions of coastal residents.
This emerges from the fifth report of the Copernicus marine environment monitoring service, which 150 scientists publish once a year on behalf of the European Commission.
The report names the worst consequences: The warming of the oceans and the melting land ice lead to an increase in sea levels - in the Mediterranean area by 2.5 millimeters per year and worldwide by up to 3.1 millimeters.
As an example of the already noticeable consequences, the report cites the flooding of Venice in November 2019, when the water level swelled to up to 1.89 meters.
The steady rise in sea levels is mainly due to the melting of sea ice.
Between 1979 and 2020 alone, the Arctic lost an ice surface that is about six times the size of Germany.
Since 1979, the ice has receded by 12.89 percent per decade.
The lows were recorded in the past two years.
The experts warn: If the Arctic sea ice continues to melt, this could contribute to the destruction of infrastructure on coasts, but also to regional warming and a change in global weather patterns.
Interplay of negative influences
The team has various indicators with which it assesses the state of the sea - including temperature, pH value or sea level and ice extent.
There is deterioration in almost all categories.
The average surface temperature rose in all of the world's oceans.
The warming of the oceans means that sea creatures migrate to cooler waters or the populations of species are shrinking.
At the same time, the oxygen content drops almost everywhere and the pH value drops.
The latter leads to acidification of the world's oceans, which among other things leads to the death of marine animals such as corals.
(Read our multimedia story "The world in distress" here)
The report also sheds light on the consequences for individual seas.
Extreme heat and cold waves in the North Sea lead to fluctuations in catches.
Some populations are shrinking, including sole, lobster, sea bass, and crab.
"Climate change, environmental pollution and overexploitation have caused unprecedented pollution for the ocean," says Karina von Schuckmann, chairwoman of the Ocean State Report, in a statement accompanying the report.
The oceans cover most of the earth's surface and regulate the climate. Accurate and timely monitoring is crucial in order to better understand the oceans and to be able to react to changes.
Measurements from space accurate to the millimeter
The researchers mainly use satellite observations for the report.
With the help of the Earth observation program Copernicus, they can make statements about the state of land, seas and atmosphere as well as climate change and its consequences.
Only last year the program received support from a new satellite, the "Sentinel 6".
For example, he can look at the oceans from space with unprecedented precision.
From a height of more than 1,300 kilometers, it takes millimeter-accurate measurements.
According to the European space agency Esa, it scans 95 percent of the global ocean surface in a period of ten days.
Earth observation satellites have been around for decades, the "Sentinel" satellites have been flying around the earth for several years.
sug / dpa