Climate Action | Adaptation to climate change

Sea-level rise

As global temperatures rise, sea levels will also go up. Coasts will become more vulnerable to flooding and erosion, with significant consequences for the people, infrastructure, businesses and nature in these areas.

There is a long tradition of measures to protect coasts from the immense destructive power of the seas, but more will need to be done in the coming years with the increasing climate change impacts.

The latest study from the International Panel on Climate Change – the most authoritative assessment of climate change science – predicts that sea levels will rise by 18-59cm by the end of the century (1), and even these estimates are conservative.

The global average sea level rose steadily in the 20th century at a rate of about 1.7mm per year. However, satellite observations show rises increased to around 3mm per year from 1993 onwards (2). This is predicted to accelerate even faster in future and the effects are already being felt in some areas such as low-lying Pacific Islands.

The rise in sea levels is the result of thermal expansion due to higher sea temperatures, as well as more water from melting glaciers flowing into the oceans.

In coastal areas there will be greater risks of flooding and more erosion because of the rising seas – affecting a significant number of Europeans.

Around a third of the EU population lives within 50km of the coast and these areas generate over 30% of the Union’s total GDP. The economic value of assets within 500m of Europe’s seas totals between €500-1,000 billion (3).

The sea-level rises will also disrupt coastal ecosystems and the wildlife living there.

Another impact in many areas will be a reduction in the amount of freshwater available as sea water pushes further into underground water-tables.

Sea-level rises also mean higher wave and storm surges, which a much greater area along the coasts that will be vulnerable to damage from winds and flooding.

Impacts

Different European marine basins face different challenges and will have to adopt adaptation strategies tailored to specific conditions:

• Baltic Sea: although vulnerability to coastal flooding and erosion is low here, rising sea surface temperatures will have a notable impact on ecosystems, especially migratory marine species;
• North Sea: will experience significant sea-level rises creating a high risk of flooding in many low-lying areas, for instance in Belgium and the Netherlands. This will be a major concern given the high concentrations of population and economic activities in these areas;
• Atlantic Ocean: the main climate risk is flooding due to sea-level rises, as well as changes in the direction and power of waves;
• Mediterranean Sea: the most significant issue is freshwater shortages. Salt water intrusion, coupled with longer dry periods, will put additional pressure on freshwater availability. This area is highly vulnerable to erosion, but sea-level rises are not too great a risk with few areas of the coastline below 5m elevation;
• Black Sea: erosion is the most significant climate-related problem and the area is vulnerable to the impacts of sea-level rises on habitats and eco-systems;
• Outermost regions/islands: these areas are particularly vulnerable to climate change, with high concentrations of population and activities along coastlines, remoteness from the mainland, and economic dependence on a few products and sectors (often tourist-related). Ecosystems can also be particularly sensitive in these areas.

Adaptation actions

Each of these areas will need additional protective actions to cope with the effects of sea-level rises, including replenishment of sand, sea walls, raised buildings and revised planning laws in vulnerable areas. These measures must take a long-term view.
The consequences are relevant for many different sectors of society – for instance, industry, energy, planning or natural resources.

This will involve considerable changes in the coming years and require significant investments. However, the dangers and costs of not doing anything are much higher – the annual cost of inaction is estimated at around €6 billion by 2020 and rising even higher by 2080. The net-benefits, on the other hand, are put at up to €4.2 billion (4).

(1) IPCC 4th Assessment Report, synthesis Report, p8
(2) IPCC 4th Assessment Report, Ch5, p387
(3) ‘Economics of climate change adaptation in EU coastal areas’ report, p3
(4) ‘Economics of climate change adaptation in EU coastal areas’ report, p8