06.06.2012 - Rio+20

Blue Forests: the Earth’s other lung

New research has demonstrated that sea grass beds can store up to 83,000 metric tons of carbon per square kilometer, mostly in the soils below them. In comparison, a typical terrestrial forest stores around 30,000 metric tons per square kilometer, most of which is in the form of wood.

57% of atmospheric carbon captured by living organisms is captured, in fact, by marine organisms, and of this between 50 and 71% is captured by the ocean’s vegetated habitats including mangroves, salt marshes, sea grasses and seaweed, so-called blue forests, which cover less than 0.5% of the seabed. These key coastal habitats represent an important opportunity for ecosystem-based climate mitigation (known as ‘blue carbon’) which also preserves the essential ecosystem services of these habitats.

Who is affected and why does it matter?

Human activities are threatening these coastal ecoystems. For example, shrimp farming is a huge driver for mangrove deforestation.  When lost, these coastal ecosystems (mangroves, tidal marshes, and seagrasses)  stop sequestering carbon and release what they have stored, thus becoming new sources of carbon emissions.

The destruction of the earth’s other lung concerns every one : the effects of climate change include more violent storms, sea level rise, floods and ocean acidification. It impacts on food production, water availability and ecosystems such as coral reefs, forests and wetlands. A major concern is how rapid climate change will magnify existing environmental stresses and contribute to food insecurity, conflict over resources, and loss of livelihood for millions..

For coastal populations, coastal ecosystems provide many services.

Indeed, mangroves

  • provide habitats, shelter and feeding grounds for many species 
  •  provide economic opportunities through sustainable use of wood
  • act as buffers (mangroves prevent erosion by absorbing heavy wave impact and dissipate wave energy from severe storms such as hurricanes) and flood plains (by absorbing excess water during periods of heavy rain)
  •  Mangroves and sea grass are interdependent nursery habitats.

"The Tana Delta wetlands, which support numerous lives, are now becoming seasonal, while others have dried out completely. This has affected local livelihoods, especially the pastoralists who have lost almost all their flocks due to the continued dry spell. These critical ecosystems used to act as fallback areas for pastoralists during dry seasons. Salt infiltration into farms is now being experienced by farmers who have never witnessed this before. This is perceived to result from rising sea levels and to be due to the fact that the mangrove vegetation along the coast has been degraded through deforestation," testifies a participant of the Climate Frontlines forum.

Preventing degradation and destruction and promoting restoration of coastal ecosystems is a significant tool which can be used to mitigate climate change.

What is UNESCO <a name="_GoBack">doing?</a>

IOC-UNESCO Nutrients and Coastal Impacts Research Programme focuses on interactions between climate, nutrients, and coastal dynamics, and the challenges and opportunities that resulting ecosystem changes pose for tourism, institutions and governance. Through this activity, IOC is an active partner in the Global Partnership for Nutrient Management, which strives to deliver better tools for management of nutrient loading to the marine environment.

The Harmful Algal Bloom Programme fosters effective management of, and scientific research on, harmful algal blooms to understand their causes, predict their occurrences, and mitigate their effects.

UNESCO-IOC is a sponsor of the joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP), the United Nations mechanism for collaboration and coordination which conducts assessments and in-depth studies to evaluate the state of the marine environment, including socio-economic aspects, and identify emerging issues.




<- Back to: Rio+20
Back to top