Editor’s note: Here is a guess post from the always informative and insightful Patriot News ClearingHouse. This post makes the important point that there are multiple elements of human agency that have contributed to the extent of human (and otherwise) catastrophe from Cyclone Nargis. And, let us remember, that mangrove swamps/forests do far more than ‘simply’ protect a coastline from storm surges. In any event, over to PDNC …
Source: Mangrove Cluster on Banks of River Given the number of deaths caused by the Burma cyclone, one question is what could have been done beforehand to better protect people. One answer is that we need to stop destroying our natural resources. Mangroves are natural buffers which decrease the severity of impacts from storms. The destruction of mangroves is a contributing factor to the death toll from the cyclone because people simply did not think of the environmental and human consequences of destroying the natural buffer. Contrary to WH spin, the mangroves may have provided better protection of human lives than even government warning systems.
Source: Underwater Root System of Mangrove A mangrove forest or swamp is essentially trees and shrubs which love living in tropical and sub-tropical tidal habitats, with roots spreading underwater and above water, creating a thicket of branches and roots as a protective barrier for communities:
Mangrove swamp is an easily recognized habitat along tropical and subtropical coastlines and brackish estuaries and deltas, where evergreen trees and shrubs thrive in tideland mud or sand flats inundated daily with sea water. These flats are found mostly along bays and inlets protected from heavy waves. Some coral reefs on islands can support mangal in relatively high energy environments.
The plant community of a mangrove swamp is most commonly termed mangal, a forest with a dense canopy, also known as mangrove swamp forest or, simply, mangrove. Although mangal occurs along more than two-thirds of all saltwater tropical coastlines, parallel to the shoreline, this is a very narrow, fringing forest, and, hence, less than one-tenth of one percent of the earth’s surface is inhabited by mangal.
Credit: Philippe Rekacewicz, UNEP/GRID-Arendal Mangroves are located worldwide, but the greatest diversity is found in Southeast Asia.
The Irawaddy Delta region, which has been declared the worst hit by the cyclone, was a wetland of mangrove forests until the British colonial rule cleared the forests for rice production. Over the years, more mangrove forests were cleared for various reasons, such as military demands during WWII and more recently to provide fuel wood or for developments, such as urban expansion or industrial shrimp aquaculture:
According to Burmese researchers, during a period of 75 years (1924-1999), 82.76% of the mangroves of the Irrawady were destroyed and globally, less than half the world’s mangrove forests remain–around 15 million ha (around 37 million acres). The FAO estimates a 1% annual loss of mangroves worldwide, which signifies a 150,000 ha (367,500 acres) loss per year.
Credit: Mangrove Photo by F3rn4nd0 Common sense and anecdotal evidence suggest that mangroves serve as natural barriers or dykes to storm surges associated with hurricanes and tsunamis because their incredible root system impedes water flow and wave energy. After the Indian Ocean tsunami, a UN official “agreed with conservation groups that the swamps and reefs not already destroyed by humans may have reduced some of the damage caused by the tsunami.” There is now scientific evidence to support these common sense conclusions.
One study (How effective were mangroves as a defence against the recent tsunami?) was partially triggered by the question of how many lives could have been saved if people had not destroyed mangroves, and it yielded some interesting results indicating that “human activity exacerbated the damage inflicted on the coastal zone by the [Indian Ocean] tsunami.”
Source: Mangrove Roots Branching Out on Beach
- The “large above-ground aerial root systems and standing crops” of mangroves “function as a physical barrier against tidal and ocean influence.”
- “In the second half of the 20th century, 50% of the world’s mangrove forests have been destroyed, and current annual loss rates vary from 1 to 20%.”
Credit: Photo by Marshman
- “Our results show that, where mangroves occur in the districts visited, they did in fact offer protection. Apart from some isolated trees …, there were no records of uprooted adult mangrove trees. At most, mangrove fringes near the water edge took all the energy and were damaged (Figure 2).” Some mangrove trees had “leaves bent or torn off,” while others “stood firm against the ocean surge.” (pictures at link)
- “Our surveys of villages and post-tsunami observations make it clear that mangroves play a critical role in storm protection, but with the subtle point that this all depends on the quality of the mangrove forest. We also found that there can be contributions to protection against ocean surges from other coastal vegetation types: salt marshes, seashores sand dunes and their vegetation (Figure 4). The more general message is that how humans use, plan and manage their habitats and landscapes can have profound and undesirable consequences.”
- While Bush focused on the failure of the government to warn people, the researchers found that mangrove protective barriers may be far more effective than government warning systems:
“The conversion of mangrove land into shrimp farms, tourist resorts, agricultural or urban land over the past decades, as well as destruction of coral reefs off the coast, have likely contributed significantly to the catastrophic loss of human lives and settlements during the recent tsunami event. While it may be a good investment to establish early warning systems for the next tsunami, it could be far more effective to restore and protect mangrove forests and other natural defenses in parallel. In fact, if we had early warning systems that cautioned us about mangrove degradation, and if we then acted to correct the mangrove degradation, not only would we save lives, but we would also minimize property damage and loss of subsistence livelihoods.”
Another study similarly found that mangrove forests “helped save Sri Lankan villagers during the Asian tsunami disaster, which claimed the lives of more than 200,000 people.” For example, comparing the deaths sustained between two villages protected or unprotected by mangroves, “two people died in the settlement with dense mangrove and scrub forest, [as compared to] up to 6,000 people lost their lives in a nearby village without similar vegetation.”
A study on the protective role of coastal vegetation assessed coastlines after the Indian Ocean tsunami and concluded that mangroves may decrease the destructive forces of storm surges. The study found that “little could have prevented catastrophic coastal destruction” in those areas which faced “maximum tsunami intensity.” However, other areas with “coastal tree vegetation were markedly less damaged than areas without.” The study findings suggested that mangroves “may shield coastlines from tsunami damage by reducing wave amplitude and energy.”
The Mangrove Action Project (MAP) advocates re-establishing the mangrove buffer zones to coastal areas to reduce or prevent future disasters.
“This latest disaster in Burma is a grim reminder of other recent natural disasters,” said Alfredo Quarto, MAP’s executive director, referring to the 2004 Indian Ocean Tsunami that left over 200,000 dead or missing and the 1999 Super Cyclone that hit the coast of Orissa, India that killed over 10,000. “The force of the cyclone could have been greatly lessened and much loss in life and property damage could have been averted if healthy mangrove forests had been conserved along the coastlines of the Irawaddy Delta,” he added.
While mangroves may provide better protection than a warning system, our preparation and response to intense storms should be multifaceted. Governments need to be held accountable for their role in delaying any warning to the people. However, the world also needs to focus on replacing the mangroves destroyed. The intensity and frequency of storms may increase due to global warming, which is another man-made crisis. It is long past time for the world to stop being simply reactive to climate events caused partially by our refusal to be responsible stewards of our environment. Instead of spending millions on recovery and reconstruction after the extreme climate event, why not spend millions now to prevent or reduce the number of people who will be killed if we do nothing.
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