Nature's Forts Key to Weathering Storms
This story is part of Macaranga’s #SeaWorld series.
(Feature image: Mangroves’ density and root structure effectively protect coasts against storm surges. | Pic by: SL Wong)
THE LAST south-east monsoon was bad for Sabahans. Over 13,000 or 93% of the country’s flood victims were in Malaysia’s poorest state. Those living by the coast were hit hard.
“On Christmas Day, there was a combination of a storm and king tide. This caused a lot of damage in Kota Belud, Pitas, Sandakan and Kota Kinabalu,” recounts Malinda Auluck, an environmental consultant who specialises in shoreline management.
“One of the worst cases was in Pulau Mantanani where several houses collapsed. Some were operating as homestays, so this has impacted the livelihood of a community already struggling to bounce back after the pandemic.”
More and more of Malaysia’s most vulnerable communities on islands and mainland coasts are suffering from the impacts of storm surges. And Malaysia has a lot of coast – 4,800km of it.
The government forecasts that climate change impacts could “affect almost 2.5 million of the population covering 16% of our land area (50,000 sqkm)” (NAHRIM-2017).
Because of the the warming planet, storm surges are going to get more intense (see pulldown). This, along with rising sea levels are key threats to coasts, notes Malaysia’s latest national climate action report to the United Nations Framework Convention on Climate Change (UNFCCC; 2021).
Storm surges are a temporary rise in sea level in a specific area caused by storms. When sea levels rise because of the climate crisis, this boosts storm surges, according to climate science hub Climate Signals. What’s more, as the planet warms, storm surges in the tropics intensify and swell, which then push waves further inland, worsening flooding. Sea levels in Malaysia are projected to rise by 0.28–0.74 m by 2100 (NAHRIM-2017).
The impacts are escalating in number and scale in terms of floods, shoreline erosion and permanent inundation of land. Already, Malaysians are paying billions of ringgit in damage, social displacement and disrupted livelihoods, and tragically, loss of human lives.
The thing is, Malaysia already has in place highly effective natural forts against the onslaught of warming seas: mangroves.
Because of their density and aerial roots, coastal-dwelling mangroves can mitigate storm surges by slowing the flow of water and reducing surface waves, especially fast-moving surges. In fact, Malaysia has the 6th largest mangrove cover in the world at 630,000 ha. Around 60% of that is in Sabah, of which almost all are forest reserves.
“As long as they remain protected, they remain intact, this is our defence against storm surges,” says Auluck.
Further out to sea
But mangroves are not the first line of defence against storm surges. That’s the role of another marine ecosystem further out to sea: coral reefs.
“[Coral reefs] also dissipate wave energy. But I want to emphasise that healthy coral reefs [are what] help. If you have damaged coral reefs, it’s just a massive amount of rubble rolling with the waves so it doesn’t dissipate wave energy.”
Coral reefs in Malaysia are however, highly threatened, not least by warming seas that have and can wipe out entire reefs through bleaching.
Nonetheless, scientists are digging deep into science to save reefs (see Photo Essay).
And then there are seagrass meadows, Malaysia’s third coastal ecosystem that helps mitigate climate impacts. Seagrasses grow between coral reefs and mangroves.
The three ecosystems working in concert are especially effective against storm surges, explains coral ecologist Affendi Yang Amri.
As winds push stormy waves towards the shore, the waves hit coral reefs first. These will absorb most of the energy. When the waves next hit seagrasses, the leaves dissipate more energy. By the time the weakened surge hits mangroves on the shore, the latter’s roots absorb the last of the energy.
“If you have all three ecosystems in front of [a coast], you are the safest from erosion and storm surges,” sums up Affendi.
Adapting to rising seas
The ecosystems could theoretically continue protecting coasts even in the face of rising seas. They do this through accretion, basically ‘building’ substrates or land to maintain ideal conditions to thrive.
As sea levels rise, coral reefs build upwards while seagrasses and mangroves trap sediments with their roots and ‘migrate’ landward.
However, Affendi thinks sea levels are currently rising too quickly. And when developers build behind mangroves – as they tend to – they leave no space for mangrove to expand.
The catchphrase for protecting, managing and restoring ecosystems is Nature Based Solutions (NbS). As defined by IUCN, these actions work to benefit societies and nature.
Specifically for coastal Malaysia, NbS refers to actions on coral reefs, mangroves and seagrasses. A key 2020 report provides valuable baseline data on the coastal NbS landscape, as collated, categorised and evaluated for the first time by 14 experts in various NbS fields.
They identified 229 actions. These range from reef balls in Sarawak and translocation of seagrass sprigs in Sabah, to mangrove replanting in Penang and local community co-management of the Pulau Tioman Marine Park.
Nonetheless, on coasts where two or all of these ecosystems are found together, they should be collectively protected, managed and restored.
Key research urging this approach states that using only a single habitat to protect the coast reduces natural systems to mere alternatives of man-made coastal structures.
Doing so “underutilises the potential of all the habitats present on the entire seascape”.
However, policies and management of each ecosystem tend to be isolated from other ecosystems, says marine biologist and policy maker Cheryl Rita Kaur.
“Marine parks are gazetted to conserve coral reefs… Mangroves have their own policies, and their own protected areas through [government] gazettes. But seagrasses [face] a bigger issue in Malaysia – they don’t have their own protected status. At the same time, there is a huge gap in policy and enforcement.
“There isn’t much seagrass now compared to 10, 20 years ago. And it’s mainly due to coastal development.”
Nonetheless, Cheryl says mangroves and seagrasses have recently become “sexy” due to the spike in carbon offsetting interest from the government and corporations. And it is due to the ecosystems’ superpower in absorbing and storing carbon.
Coastal habitats are much better at capturing and storing carbon than terrestrial forests, says Cheryl. Policy-wise, this so-called blue carbon mechanism gained traction in 2021 after Malaysia committed non-conditionally to reduce greenhouse gas emissions by 45% by 2030.
Interest was further fuelled by the rise in carbon trading and last’s year’s launch of a Malaysian carbon exchange.
Low cost carbon capture
Blue carbon is also attractive because it is cost-effective, says Cheryl who is with the Malaysian Institute of Maritime Affairs .
An ‘intervention’ could be as simple as leaving trees and seagrasses where they are, to do their thing – sequester carbon. “Using these carbon services could also provide incentives for private investments in conservation.”
She cautions however, about gaps in knowledge, data, policy, and management.
Far from ready
Affendi is more blunt. “We are not ready for blue carbon. The basic data and science are not there.” He says conservationists are “inundated” by requests from companies to offset their carbon emissions by buying credits generated through mangrove and seagrass restoration.
“But we don’t know [mangroves and seagrass] carbon sequestration rates for Malaysia. For seagrasses, we don’t even know the area.” In fact, Macaranga found that official mangrove coverage in Peninsular Malaysia might not be accurate either.
While the interest in blue carbon could be boon for coastal conservation, it would backfire if it further segregates management of coral reefs, seagrasses, and mangroves.
Affendi is certainly wary that a focus shift to blue carbon could sideline coral reef conservation – and ironically, the blue carbon ecosystems themselves.
“Corals are not a blue carbon thing because they do not sequester carbon… But if you are neglecting the marine ecosystem that is protecting the blue carbon ecosystems, then it’s a bit ridiculous. So you need to be looking at it as a whole.”
This story is part of Macaranga’s #SeaWorld series. The series is supported by the Embassy of France in Kuala Lumpur. Check out the related photo essay: Urgent Search for Malaysia’s Super Corals.
Chee S.Y., et al. (2021). Enhancing Uptake of Nature-Based Solutions for Informing Coastal Sustainable Development Policy and Planning: A Malaysia Case Study. Frontiers in Ecology and Evolution Vol. 9.
Ferrario, F., et al. (2014). The effectiveness of coral reefs for coastal hazard risk reduction and adaptation. Nature Communications 5, 3794.
Guannel G., et al. (2016) The Power of Three: Coral Reefs, Seagrasses and Mangroves Protect Coastal Regions and Increase Their Resilience. PLoS ONE 11(7): e0158094.
Masselink, G., et al. (2020). Coral reef islands can accrete vertically in response to sea level rise. Science Advances Vol. 6 (24).
Ministry of Natural Resources, Environment and Climate Change. Malaysia’s Fourth Biennial Update Report submitted to the United Nations Framework Convention on Climate Change. 2022.
National Hydraulic Research Institute of Malaysia (NAHRIM). Impact of Climate Change – Sea Level Rise Projections for Malaysia. 2019.
PLANMalaysia. National Coastal Zone Physical Plan (NCZPP) 2. 2021.