1. An Introduction to the Tropical Pacific and Types of Pacific Islands

The Pacific accounts for about 46% of the Earth’s water surface and about one-third of its total surface area, making it larger than all of Earth’s land area combined. The tropical portions are dotted with thousands of islands that despite their geographic position differ considerably climatically. A west-to-east decrease in rainfall is particularly notable during a typical year, amidst seasonal shifts in the trade wind-driven Intertropical Convergence Zones. Additional changes are superimposed by the El Niño Southern Oscillation, which has the effect of moving the rainfall and warm water from west to east, periodically imposing disruptive floods in relatively dry climates, and droughts in areas that are normally wet. Likewise, occasional but destructive cyclonic storm tracks are common north and south of the equator. Islands in the tropical northwestern Pacific are particularly vulnerable to typhoons. High volcanic islands exhibit a distinct climate compared with low coralline islands and this is reflected in the vegetation found on each. Coral reefs are typical of most tropical islands in the Pacific, but they differ in form that includes fringing, barrier and atoll reefs. A brief description of geological processes that control reef formation and reef islands is also given.