Terrain shapes and bedrock
The islands in the three included island groups are all coral islands, lower than 8 m above sea level, and have been built up on the sides of volcanoes that are sinking. They consist of barrier reefs and annular atoll reefs, which normally have a lagoon in the middle and consist of lime, mainly deposited by coral animal colonies. On the sea side, the atolls are usually surrounded by talus, often to a relatively large depth. On the lagoon side there is a shallow platform. Only Banaba, formerly the Ocean Island, which lies southwest of the sixteen Gilbert Islands reaches a greater height (81 m above sea level) due to the phosphate mass located in the interior of the island.
According to COUNTRYAAH, the islands of Kiribati, located on both sides of the equator, have a humid tropical climate. During the April-October period, the northeast passage dominates, which makes the climate more pleasant. During the rest of the year, strong west winds blow, which can also cause heavy rain.
According to BRIDGAT, the rainfall in the Gilbert Islands varies from 2,500 mm per year in the north to 1,000 mm in the south. Severe droughts can also occur on the lowest islands. The annual average temperature is around 28 °C.
Plant-and animal life
Due to the isolation of the islands, plant and animal life on land is considerably poor in species. However, the surrounding coral reefs are rich.
The largest island, Kiritimati (Christmas Island), houses only about 150 species of vascular plants. The natural vegetation is rainforest-like, but nowadays the islands are dominated by coconut trees (both grown in large plantations and wild along the beaches), screw palms, figs and breadfruit trees.
Wildlife is mainly made up of sea birds. Of the less than 30 species of birds that breed, only one seal, the cane singer Bokikokiko (Acroceʹphalus aequinoctiaʹlis), is endemic in the Line Islands. Otherwise, liras, soles and terns dominate.
Kiribati has no national parks but in 2009 there were about ten protected areas. The largest of these is the 2008 Phoenix Islands Protected Area (410 500 km2), which is one of the world’s largest marine protection areas. The area, which includes housing approximately 200 coral species, 500 fish species, and 18 marine mammals, was listed on UNESCO’s World Heritage List in 2010.