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Climate Change and Biodiversity in Melanesia (CCBM) Project Report

Bishop Museum, Pacific Regional Environment Programme (SPREP) along with the Pacific Science Association (PSA) and Indo-Pacific Conservation Alliance (IPCA), have announced initial findings in their MacArthur Foundation-funded study, Climate Change and Biodiversity in Melanesia (CCBM). These findings were announced at the 8th Pacific Islands Conference on Nature Conservation and Protected Areas held in Alotau, Milne Bay province in Papua New Guinea in October 2007.

The global warming project was launched in September 2007 with a workshop of experts, which included climate change and biodiversity scientists specializing in the Melanesian region. Dr. Allen Allison, Dr. Stephen Leisz (Geospatial Scientist at Bishop Museum), and John Burke Burnett (Executive Secretary of PSA) hosted the meetings to assess the best “State of the Science” regarding projected impact of climate change on biodiversity in Melanesia. Melanesia (Papua New Guinea and Indonesia’s Papua Province, Solomon Islands, Vanuatu, New Caledonia, and Fiji) is one of the world’s highest biodiversity areas with many endemic species and the planet’s richest coral reefs. Being largely a region dependent on agriculture, fisheries and other natural resources, the attendant socio-economic and health implications of climate change on Melanesia’s ecosystems are potentially grave. The importance of preserving Melanesia’s rich biodiversity should thus be considered in terms of human societies’ dependence on ecosystem services it provides.

A key point highlighted by the workshop participants is that projections by the world’s preeminent body on climate science, the U.N. Inter-Governmental Panel on Climate Change (IPCC), lack precision on specifically how climate change will affect Melanesia. Computer climate models do not yet have a sufficiently fine-scale resolution to “see” islands. An additional complication is the inherent uncertainty of different possible future global carbon emissions scenarios. Because of these uncertainties, the CCBM study is important to determine how projected broad-scale climate pattern changes will specifically impact the Melanesia region. So while many ambiguities remain, several consistent patterns have begun to emerge.

Warming and El Niño

It is likely that warming in the western tropical Pacific will closely follow the projected global average warming rate of 1.8° to 4.0° C (3.2° to 7.2° F) by the year 2099. El Niño/La Niña cycles (known as ENSO) are known to have major effects on the climate of Melanesia. Dr. Axel Timmermann of the International Pacific Research Center (IPRC) at the University of Hawaii at Manoa said that the often-repeated statement that global warming in the Pacific will result in “more persistent El Niño-like conditions” is somewhat misleading. El Niño refers to a specific kind of cyclic state that may or may not resemble future climate patterns under warming scenarios. In Melanesia, El Niño generally results in hotter and drier land conditions, but paradoxically—relatively cool sea temperatures. Conversely, La Niña conditions in Melanesia mean relatively wet conditions on land—which implies cloudiness that tends to suppress temperatures—but far hotter sea surface temperatures. This results in more frequent and intense coral bleaching.

Large-scale changes in ocean circulation patterns in the Pacific are thought to be another highly plausible result of global warming, but it is not yet possible to accurately predict exactly how, where, and what these circulation changes may be. Increased temperature, changes in rain fall, wind speed and direction, sea level rise, and increased intensity of tropical cyclones are likely scenarios for Melanesia, but since regional climates in the Pacific region are strongly affected by ENSO and ocean circulation—factors that heavily influence such events—it is not yet possible to estimate with precision to what degree these changes will happen, or how they vary from one island to another in the western tropical Pacific.

SSTs and Coral Bleaching

Sea surface temperatures (SSTs) are warming fastest near the equator and less quickly towards the higher latitudes (both north and south of the equator). So while all of Melanesia’s reefs and oceans will become warmer, resulting in an increase in coral bleaching events, northern Melanesia is likely to experience more frequent and prolonged coral...