Marine ecosystem resilience 

Marine ecosystem resilience 

© Lauric Thiault

Coral reefs, mangroves, sea grass meadows and salt marshes are considerably under threat from human-induced climate change. These ecosystems not only support human activities, such as fishing and tourism, hold moral, cultural and aesthetics values; they play a critical role in mitigating and adapting to climate change.

Home to the richest and most diverse biodiversity of our ocean, they also act as buffers against sea-level rise and increased storm intensity. It is of highest importance to preserve and restore marine ecosystems.

In numbers:

  • Coral reefs represent only 0.2% of the ocean surface and are home to 30% of its known marine species. However, estimates show that 20% of the world’s coral reefs have been lost and another 20% degraded.
  • Today, 75% of the world’s coral reefs are threatened by a combination of local sources (e.g. overfishing, coastal development, pollution) and thermal stresses (e.g. rising ocean temperature, acidification). This number is expected to increase to 90% by 2030 and almost 100% by 2050.
  • Moreover, the Global Ocean Forum 2016-2021 roadmap argues that the ecological benefits of coral reefs represent US$ 30 billion yearly, and directly support 500 million people for fishing.

According to the Global Mangrove Alliance, we have lost 50% of mangroves in the past half century, with 20% of mangroves lost from 1980 to 2005. The cumulative loss over the last 50-100 years ranges from 25-50% of total global area for mangroves, salt marshes and seagrasses ecosystems. At current conversion rates, 30-40% of tidal marshes and seagrasses and nearly 100% of mangroves could be lost in the next 100 years. Additionally, these coastal ecosystems release a significant amount of carbon dioxide when degraded – estimated to be equivalent to the United Kingdom’s annual carbon emissions. Coastal blue carbon ecosystems can store a particularly high amount of carbon in the biomass of plants and soils – up to six meters deep for up to a millennium – therefore releasing high amounts of CO2 when degraded or lost.

Consequences of increased CO2 on ecosystems

Coral reefs, mangrove forests and other blue carbon ecosystems – despite providing vital services and being critically endangered – are often neglected in national and international policy-making processes. Although, these ecosystems provide adaptation benefits by acting as nurseries for fishing and protecting communities and environments against storms, sea-level rises and coastal erosion. The Global Ocean Forum Roadmap 2016-2021 calls for ‘coastal adaptation’, by restoring mangroves and reefs, and for the inclusion of ecosystem-based adaptation in National Adaptation Plans (NAPs), with a coherent and global view of ecosystem services and interactions within and between ecosystems.

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