«Sea level rises – climate crisis swallows up coastal areas of Europe»1 – This is one of many headlines about climate change. In recent years there has been more and more news on this topic and many also cover sea level rise. What is sea level rise and what causes it? How will the sea level change and what are the consequences?
Sea Level — Meaning
Sea level can rise or fall. For example, when it rises, flooding can occur, and when it sinks, the seabed becomes visible.
as Sea level is the height of the sea surface.
Sea level can fluctuate for a variety of reasons. These include ocean currents, ebb and flow, and trade winds.
You can read more about the measurement and types of sea level in the «Sea level» explanation!
sea level rise — causes
Global sea levels have risen by an average of 15 centimeters over the last century. The main reason for this is that climate change and the thereby elevated temperatures on earth.
To find out more about climate change, please read the appropriate explanation!
Various factors play a role in explaining sea-level rise. One distinguishes between steric and eustatic factors.
Steric sea level rise
To the steric sea level rise one counts the factors that lead to this water further expands. The water can through the surrounding continents but do not avoid it, which is why the sea level rises.
warming of the oceans
The water of oceans always warmerbecause they absorb most of the heat generated by the climate change arises. The warmer the water, the lower is his density and a substance with a low density takes up more volume for the same mass.
So the volume of water is increasing and sea level is rising. the oceans warm up in different regions at different rates, which is why local and regional sea levels rose at different rates.
Reduction of salinity
Another cause of sea level rise, but less serious, is that Reduction of salinity. The water expands further when the salinity is lower. As a result, the density decreases and the sea level rises.
But why does the salt content drop? When the ice masses melt in Greenland, for example, the fresh water stored in them flows into the sea. This causes the salt content to decrease.
Eustatic sea level rise
From eustatic sea level rise do you speak when more water in the seas comes and the sea level rises as a result. This happens due to the following factors:
- ice sheets
- melting of glaciers
ice sheets
There are two ice sheets: one is in the Antarctic and one in Greenland.
It is called an ice sheet large masses of ice and glacieroccupying almost an entire continent.
Due to global warming and rising temperatures on Earth, the ice sheets are melting. Ice melt in Greenland and Antarctica accounts for about a tenth of the total increase, or about 0.35 cm per decade.
Melting Glaciers
the glacier in the polar regions and in mountain ranges such as the Alps. The outflowing meltwater flows into the oceans and then causes sea levels to rise.
sea level rise — Forecast for 2100
The sea level is rising faster and faster. In the last century it has increased by 15 centimeters at 2.1 millimeters per year. Sea level is currently rising due to climate change more so twice as fastl, with 4.8 millimeters annually.
Until the year 2100 could the sea level so 30 to 100 centimeters increase. Researchers even speak of one sea level rise of up to 1.5 meters by 2100. This can happen if greenhouse gas emissions continue to increase because our climate system is sluggish.
Sluggish in the context of climate means that the oceans reacts with a delay to changes in the climate and the effects of the current environmental pollution will only become visible in a few years.
Of the sea level rise is therefore not due to the current emissions, but to those of the last few decades. This also means that sea levels will continue to rise, even if there is no longer a contributing factor from now on.
Sea Level Rise — Consequences
Sea level rise has had some negative effects:
- floods
- Threat to the ocean ecosystem
- Uninhabitability of coastal regions and islands
- climate refugees
- conflicts
floods
By the melting the glacier at the north and south poles and other factors mentioned above, there are floods in many regions. the frequency of storm surges has increased in recent years.
The city of Norfolk in the USA is repeatedly affected by floods. On average, a street in Norfolk is flooded every two to three weeks. If sea levels continue to rise, the place will be uninhabitable in a few decades.
The floods, which are favored by the rise in sea level, have serious consequences for people and the environment. On the one hand, habitats and infrastructure are being destroyed and, on the other hand, there is a shortage of fresh water in many areas.
freshwater scarcity
On islands, storm surges cause saltwater to enter freshwater reservoirs when flooded. This can lead to a scarcity of fresh water come.
Threat to the ocean ecosystem
The ocean ecosystem is under threat because of global warming and melting glaciers salinity in the water and the water will sour. This threatens the animals and plants that live in it and in turn has an impact on us humans. For example, warm oceans absorb fewer exhaust gases and more CO₂ stays in the The atmosphere.
You can find out more about the ocean ecosystem in the «Ecosystems» explanation. In the explanation of the «oceans» you will also learn what an acidic sea is.
Destruction of the Wadden Sea
Also in Germany the consequences of rising sea levels become visible, for example through the destruction of the Wadden Sea.
The Wadden Sea is a part of the sea that is strongly influenced by ebb and flow. The sea floor is called mud flats.
Many tidal flats be by the year 2100 permanently below the water surface and flooded be. This threatens breeding grounds for shorebirds.
Uninhabitability of islands and coastal areas
For example, if sea levels continue to rise, coastal regions or islands are no longer inhabited. Especially flat and small islands, for example in the tropics are endangered.
The consequences of sea level rise the the regions can make uninhabitable, sind coastal erosion and storm surges.
Venice is from sea level rise threatened and has therefore built a large flood protection system consisting of 78 flood gates that are raised at high tide.
However, many poorer regions of the world have no protection systems that protect the country from erosion and floods.
Consequences for developing countries
Especially developing countries are of the consequences of sea level rises affected. For example, they do not have, as in most of the coastal areas of Germany, coastal protection through dikes.
A dike is a dam on the water that prevents water from entering the land behind the dyke from the sea, lake or river.
The dyke is a kind of protective wall that can protect against flooding. So when floods occur in developing countries, they are more affected. The rise in sea level endangers livelihoods at the coast from Bangladesh, India, Vietnam, Indonesia, Thailand, the Philippines and Japan.
climate refugees
The livelihood of residents in particularly flat and small regions is through the sea level rise threatened. That is why more and more people are fleeing from these regions to other countries on the mainland. These people are then called climate refugees designated.
This poses new challenges for the countries to which they flee, as these people have to be cared for and accommodated. It is also problematic because there are officially no climate refugees and therefore no asylum can be granted to them.
The first climate refugees were already in 2007. Almost 100 residents of the Carteret Islands in Papua New Guinea had to be resettled.
conflicts
Besides, it can too Conflicts over land and housing come when regions through the sea level rise are no longer habitable. people at the coast live, have to move to other areas.
Sea Level Rise — Safeguards
One of the biggest drivers of sea level rise is climate change and the associated rise in temperature. Since the oceans are sluggish and the change in climate change arrives with a delay, the climate change stopped or slowed down will. Actions taken today will have repercussions for decades to come.
To reduce the consequences of sea level rise, in coastal regions coastal protection to be built in the form of dikes that support the living there population protect against floods, for example.
However, this is not possible for flat islands and protection cannot be built.
A floating city is being built in the Maldives to provide housing for around 20,000 people at risk from flooding.
One natural process that cannot be influenced by humans but slows sea level rise is that eruption of a volcano. During a large eruption, the volcanic ash in the the atmosphere solar radiation weakened. the oceans heat up less and the volume does not increase as quickly.
When Mount Pinatubo in the Philippines erupted in 1991, sea level rise slowed by 0.02 millimeters per year for 25 years.
The sea level is different in different places and also rises at different rates. Of the Sea level rise, which has been caused in particular by the climate change has increased sharply and continues to increase, brings with it many negative effects. The consequences affect both humans and animals and the Nature.
Sea Level Rise – The Most Important
- Sea level is the height of the sea surface.
- A distinction is made between steric and eustatic sea level rise.
- Until the year 2100 will dhe sea level according to forecasts 30 to 60 centimeters rise.
- Sea level rise is mainly caused by climate change and its consequences.
- There are many negative consequences for people, nature and wildlife.
proof
- krone.at: Sea level rises – climate crisis swallows coastal areas of Europe. (07/08/2022)
- br.de: The sea level is rising. (07/08/2022)
- German Climate Consortium (2019). Future Sea Levels. deutsches-klima-konsortium.de (08.07.2022)
- daserste.de: What is the sea level. (07/09/2022)