Climate Change Imperils Pacific Ocean Mangroves

Urgent action is required to safe Pacific Ocean mangroves from the impacts of rising sea levels, linked with climate change. The United Nations Environment Programme (UNEP) warns that 16 Pacific Island countries and territories could see over half their mangroves lost by the end of the century. The worst-affected areas would likely be American Samoa, Fiji, Tuvalu, and the Federated States of Micronesia.

Roughly half the world’s mangrove area has already been lost since 1900 as a result of clearances for developments like shrimp farms. About 35 per cent of this loss has occurred in the past two decades alone.

Mangroves provide important shoreline protection against disasters. Wave energy may be reduced by 75 per cent during a wave’s passage through 200 meters of mangrove forest. In addition, the health of mangroves affects the health of other economically and biologically important ecosystems, including coral reefs and seagrass beds.

The report points to several additional benefits derived from healthy mangroves:

  • Mangroves are important nurseries for fish, act to filter coastal pollution and are important sources of timber and construction materials for local communities. Pacific islanders also harvest dyes from mangroves to treat textiles, nets and fish traps.
  • The goods and services generated by mangroves may be worth an average of $900,000 per square kilometer, depending on their location and uses.
  • Studies in Thailand put the figure at up to $3.5 million per square kilometer and in American Samoa at just over $100,000 per square kilometer.
  • An estimated 75 per cent of commercially caught prawns in Queensland, Australia, depend on mangroves.
  • A 400 square kilometer managed mangrove forests in Matang, Malaysia, supports a fishery worth $100 million a year.
  • Forestry products from the Matang mangroves are worth $10 million annually, it is estimated.

The UNEP study makes a series of recommendations, including reducing pollution from land-based sources in order to make existing mangroves more healthy and resilient, restoring lost or degraded mangroves wetlands, setting back coastal infrastructure and development to allow mangroves to spread inland. These measures need to be complemented by fully implementing the Kyoto Protocol and additional cuts in carbon emissions, as well as helping vulnerable communities adapt to the sea level rise that is already underway.

The report, “Pacific Island Mangroves in a Changing Climate and Rising Seas,” was compiled by the Regional Seas Programme of UNEP, the Secretariat of the Pacific Regional Environment Programme (SPREP) based in Apia, Samoa, the Western Pacific Regional Fishery Management Council in Honolulu, United States, and more than a dozen additional agencies and organizations from the Pacific Islands region.

It is available online at http://www.unep.org/PDF/mangrove-report.pdf and at www.wpcouncil.org, and can be ordered free of charge in English from Eric Gilman, University of Tasmania, 2718 Napuaa Place, Honolulu, HI 96822 USA. Tel: +1.808.722.5424, Fax: +1.808.988.1440, Email: egilman@utas.edu.au.

United Nations Environment Programme, “Climate Change Threat to Pacific Ocean Mangroves,” UNEP News Release 2006/35, 18 July 2006.
Link: http://www.unep.org/Documents.Multilingual/Default.asp?DocumentID=483&ArticleID=5312&l=en