Nature-based solutions (NbSs) are among the most promising and cost-effective approaches in the fight to tackle the planet’s triple crisis. These are measures for the protection, restoration or expansion of healthy natural areas with the objective of enhancing their many benefits and managing them sustainably.
In coastal zones this primarily involves the restoration, renaturalization or comprehensive replanting of mangroves, seagrass meadows, coral reefs, mussel beds, salt marshes, dunes and natural floodplains. These measures are effective in facilitating:
- the removal of carbon dioxide from the atmosphere, thus limiting global warming (Mangroves, for example, can store up to four times more carbon per square metre than tropical rainforests. Natural ocean-based measures to increase natural carbon storage are known as blue carbon.);
- the creation of habitats for rich and resilient biodiversity • (Intact coastal ecosystems filter pollutants and suspended material from the water and provide organisms with protection, food and corridors for potential migration of species. The benefits: less stressed species have a better chance of adapting to climate change. For example, 4000 square metres of seagrass meadow provide a habitat and food for around 40,000 fish and 50 million invertebrates such as lobsters and shrimp.);
- the reinforcement of natural coastal protection (Coral reefs, mussel beds, seagrass meadows, kelp forests and mangrove forests help to absorb the force of waves, thus mitigating flooding and minimizing the destruction and degradation of inland coastal areas. An additional advantage: After a storm, the mangroves, mussel beds, etc. repair the damage themselves and, unlike dikes and protective walls, they grow naturally with rising sea level.);
- mitigation of the severity of local ocean acidification (By absorbing carbon dioxide from the water, seagrass meadows reduce local acidification in the ocean, for example by up to 30 per cent off the coast of the US state of California.);
- food security for coastal communities (Healthy coastal ecosystems provide a habitat and nursery for many marine organisms and seabirds. If their offspring can develop successfully as a result of favourable habitat conditions and sustainable management, the yields achieved by fishers, hunters and gatherers will increase.);
- provision of new livelihoods for people (The beauty and biodiversity of healthy coastal ecosystems attract tourists and may enable local communities to generate new sources of income and escape poverty.).
fig. 8.31 > The restoration of wetlands, along with coastal and mangrove forests, can be effective in protecting populated coastal areas from storm surges, rising sea levels and erosion.
The prerequisite for all of these functions, however, is that human societies drastically reduce their greenhouse gas emissions. For mangroves, seagrasses, kelp forests and mussels react sensitively to heat stress, extreme storms and rapidly rising sea levels. In light of the current global warming, it is also vital to allow species and biotic communities viable routes for migrating polewards. Dikes, protective walls and coastal cities paved in concrete often present insurmountable obstacles. And finally, the restoration and preservation of these natural coastal bulwarks require a considerable amount of specialized interdisciplinary knowledge, adequate funding and local communities’ participation and support. If only one of these aspects is missing, projects will fail.
fig. 8.32 > A bright idea: Women from a village on the southeast coast of India are planting mangrove seedlings along the bank of a river. Each family that takes part in this restoration project receives a goat and some chickens as payment. This incentive improves the villagers’ food supply and motivates them to participate.