much closer proximity to western Indonesia than they do to mainland Australia. They have a multicultural mix of inhabitants with Asian and European Australian ancestry, and were uninhabited when discovered by the British during the 17th century. The islands lie within the bounds of the Australian Plate, and are defined by the World Factbook as the westernmost extent of Oceania. The United Nations also include these islands in their definition of Oceania, under the same subregion as Australia and New Zealand. Climate Most of Southeast Asia have climate being tropical with being hot and humid all year round with plentiful rainfall. Northern Vietnam (including Hanoi) has subtropical climate and times to be influenced by cold waves which move from the Northeast, northern part of Central Vietnam also has times to be influenced by cold waves; in general, not all of the region is tropical and hot around year. The majority of Southeast Asia has a wet and dry season caused by seasonal shifts in winds or monsoon. The tropical rain belt causes additional rainfall during the monsoon season. The rainforest is the second largest on Earth (with the Amazon rainforest being the largest). Exceptions to this rainforest climate and vegetation are: mountain areas in the northern region and the higher islands, where high altitudes lead to milder temperatures the "dry zone" of central Myanmar in the rain shadow of the Arakan Mountains, where annual rainfall can be as low as , which under the hot temperatures that prevail is dry enough to qualify as semi-arid. Climate change Southeast Asia is one of the most vulnerable regions to climate change in the world. Climate change will have a big effect on agriculture in Southeast Asia such as irrigation systems will be affected by changes in rainfall and runoff, and subsequently, water quality and supply. Climate change is also likely to pose a serious threat to the fisheries industry in Southeast Asia. Despite being one of the most vulnerable regions to the effects of climate change in the world, Southeast Asian countries are lagging behind in terms of their climate mitigation measures. Environment The vast majority of Southeast Asia falls within the warm, humid tropics, and its climate generally can be characterised as monsoonal. The animals of Southeast Asia are diverse; on the islands of Borneo and Sumatra, the orangutan, the Asian elephant, the Malayan tapir, the Sumatran rhinoceros and the Bornean