Mangrove and climate change

Have you ever been to the mangrove forest at the mouth of Muara Angke River in North Jakarta? Here you can see ugly trees and other vegetation growing in an indescribably dirty area full of garbage and swamped with stinking water full of all kinds of solid and liquid waste.

It is hard to imagine that these same trees and vegetation called mangroves play a very critical role in our livelihood and in our fight against climate change.

For many decades, mangrove forests have not been taken seriously as an important ecosystem in our environment and have been largely neglected in all debates about illegal logging, land use change and global warming. Only in recent years have mangrove forests received more attention as people start to realize their significance to the economy and the environment.

Mangroves are trees and shrubs that grow in saline coastal habitats and occupy large stretches of subtropical and tropical coastlines around the world.

They provide not only valuable goods such as timber, fish and medicinal plants but also vital ecological services, such as prevention of coastal erosion and help buffer coastal communities against storms and floods.

According to some reports, the annual economic value of products and services that mangrove forests provide is between US$200,000 and $900,000 per hectare.

Mangrove forests are also one of nature’s best ways to combat global warming because they are so efficient in sequestering carbon.

Through photosynthesis, mangrove plants absorb CO2 from the atmosphere, store the carbon in sugars, starch and cellulose, and release the oxygen into the atmosphere.

 So, mangrove forests provide us with the fresh air we breathe and at the same time function as vast sinks for carbon. Compared to other forests, such as tropical rain forests, mangrove forests are more effective and efficient carbon storage areas because the plants very quickly develop root biomass, almost half of which is below ground.

This and the slowly decomposing thick organic layer in the soil enable mangroves to store carbon up to four times more than tropical rain forests do.

Some studies estimate that mangroves are able to sequester 3 to 4 tons of carbon per hectare per year, which is approximately equivalent to the amount of carbon that two to three motor vehicles release into the atmosphere each year.

In addition to their function as huge carbon storage areas, mangrove forests are also the first defense line against rising sea levels as they provide immediate protection to coastal communities against storm surges and floods associated with global warming.

The loss of mangrove forests would therefore damage local economies and the livelihoods of coastal communities.

It would also leave nearly half of the world’s population living in cities and settlements along the coasts less protected against global warming and consequent sea level rises.

In many parts of the world where mangrove forests have been cleared, tremendous problems of erosion and siltation have arisen, and terrible losses to human life and property have occurred due to destructive hurricanes, storms and tsunamis.

It is expected that millions of coastal residents will have to be evacuated within the next 50 years as sea levels continue to rise as a result of global warming caused by excessive CO2 emissions.

With the clearing of mangrove forests, we will lose not only the important potential for carbon sequestration offered by the mangroves but also see the release of major quantities of polluting gases from the disturbed mangrove substrate itself.

Some studies have revealed that the upper layers of mangrove sediments have a high carbon content of over 10 percent and each hectare of mangrove sediment is estimated to contain some 700 tons of carbon per meter depth.

Digging up 2 meters of soil to create shrimp ponds — for example — could result in the potential oxidation of 1,400 tons of carbon per hectare per year.

Researchers have pointed out that destroyed mangroves release as much as 10 percent of all emissions worldwide from deforestation even though mangroves account for just 0.7 percent of tropical forest areas.

Unfortunately, the negative impacts of mangrove loss are often underestimated or ignored in decision-making and development planning processes. Vast areas of mangroves have been cleared in the last few decades due to coastal development, destructive wood harvest and conversion for aquaculture such as shrimp farms.

From an estimated more than 32 million hectares ca. 50 years ago, less than half remain. Yet, their
destruction continues at a very alarming rate.

According to recent estimations, mangrove forest decimation is currently around 150,000 ha per year globally, which leads to a loss of 225,000 tons of carbon sequestration potential each year, with an additional release of approximately 11 million tons of carbon from disturbed mangrove soil each year.

For Indonesia, mangrove forests are of high importance as the country still has 2.5 to 3 million hectares of mangrove forests, or about one-fifth of the world’s remaining mangrove area.

This secures the livelihood of millions of coastal communities and protects cities and settlements along the coasts of Sumatra, Kalimantan and Papua from storms, erosion and floods caused by rising sea levels.

In the aftermath of the giant tsunami in Aceh in 2004, it was found that many lives and property were saved from the massive waves in coastal settlements with intact mangrove forests.

Indonesia’s mangrove forests could also give the country a strategic position in international discussions and negotiations about global warming and climate change as they can process the carbon emissions of at least 5 million cars each year.

Sadly, Indonesia’s mangrove forests are seriously threatened and have been cleared and degraded intensively and extensively over the last few decades. More than 1.5 million hectares have been cleared and destroyed in the last 30 years, leaving a vast area of degraded and cleared mangrove wetlands.

It is important for Indonesia to stop this and to ensure the conservation and sustainable use of existing mangrove forests, while at the same time restoring and replanting the vast areas of degraded and cleared mangrove wetlands.

There is a vast wealth of experience and learning showing that the conservation and use of mangroves can go hand-in-hand.

In West Kalimantan, there are examples of sustainable use of mangrove forests by communities for charcoal and fuel wood production, while in other places, well-planned and well-managed restoration and replanting of mangrove forests have helped increase catches of marine products and have protected coastal communities against erosion, storms and tsunamis.

However, these activities are by far not enough. They usually have limited impacts at the local level and benefit local people, but they do not make a significant contribution to address global warming.

We need to put more effort into supporting such activities, replicate and even scale them up to a level that has a significant impact to limit the effects of global warming and ensure long-term provision of important goods and services that are vital to our lives.

The technicalities should not be a problem in making this happen as the above examples have proven; nor should the costs as Indonesia has been able to finance large-scale reforestation in the past.

What is obviously missing and much needed are political will, commitment and consistency in implementing policies under a strong leadership with clear vision. These seem to be the biggest challenges in our society today.

The writer is an international senior advisor on biodiversity and climate change, Deutsche Gesellschaft für Internationale Zusammenarbeit.