Earth’s second-largest island still splits two nations
New Guinea covers about 785,753 square kilometres—the world’s second-largest island—with the planet’s third-largest remaining rainforest and unmatched island plant diversity. Torres Strait’s 150 kilometres separate it from Australia, though both sat on one shelf in Pleistocene lowstands.
A line near 141 degrees east longitude cuts the island into two roughly equal halves. The east is the mainland of Papua New Guinea, whose largest city is Port Moresby; the west, once part of the Dutch East Indies, now forms six Indonesian provinces, with Jayapura as its biggest city. Mapmakers compare the outline to a bird-of-paradise, naming the northwestern end the Bird's Head and the southeastern end the Bird's Tail.
The Spanish navigator Yñigo Ortiz de Retez coined the name New Guinea in 1545, likening local people to those of Africa's Guinea coast. Papua is older and murkier: one theory reads it as Tidore for 'not united', an outlying possession, while another traces it to a Biak phrase for the land beneath the sunset. Irian, from Biak for 'hot land', was adopted in the 1940s and used by Indonesia until 2001.
A mountain spine more than 1,600 kilometres long runs east to west, with many summits above 4,000 metres. Puncak Jaya, at 4,884 metres the highest point in Oceania, carries equatorial glaciers that have been shrinking since at least 1936. Below lie huge lowlands of wetlands, savanna and some of the world's largest mangrove forests, including Lorentz National Park, a World Heritage Site. Rainfall of 2,000 to 10,000 millimetres a year feeds rivers such as the 1,100-kilometre Sepik, the island's longest, and the Fly, which alone discharges more water than every river in Australia combined.
When sea levels dropped during Pleistocene ice ages, the island joined Australia in a single continent that archaeologists have called Sahul since 1975; the old shorelines now sit 100 to 140 metres underwater. That shared past explains the wallabies, possums and echidnas found on both sides. Apart from bats and about two dozen rodent genera, no placental mammals arrived before humans brought pigs, extra rats and the ancestor of the singing dog.
Source: New Guinea
