In human geography, there are several schools of thought. The more common school follows historical convention and treats Europe and Asia as different continents, categorizing East Asia, South Asia, and the Middle East as specific regions for more detailed analysis. Other schools equate the word "continent" to geographical "region" when referring to Europe and Asia in terms of physical geography. In European languages, the term "Asian" more commonly refers to ethnic heritage rather than a strict geographic area. In American English, "Asian" often refers to East Asians, while in British English, Asian often refers to South Asians. See the List of transcontinental countries for further geographic definitions. The term Asia Pacific generally refers to a combination of East Asia, Southeast Asia, and islands in the Pacific Ocean – and most are also considered part of Australasia or Oceania. Asia contains the Indian subcontinent, Iranian Plateau, Arabian peninsula, as well as a piece of the North American plate in Siberia. Since the 18th century Asia has been divided into several subregions independently defined from Asia as a whole. There has been no historical consensus and there is not now any universal consensus on the use of these terms, just as there is none for the word "Asia". The regions of Asia include:  A survey carried out in 2010 by global risk analysis firm Maplecroft identified 16 countries that are extremely vulnerable to climate change. Each nation's vulnerability was calculated using 42 socio, economic and environmental indicators, which identified the likely climate change impacts during the next 30 years. The Asian countries of Bangladesh, India, Vietnam, Thailand, Pakistan and Sri Lanka were among the 16 countries facing extreme risk from climate change. Some shifts are already occurring. For example, in tropical parts of India with a semi-arid climate, the temperature increased by 0.4 °C between 1901 and 2003. A 2013 study by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) aimed to find science-based, pro-poor approaches and techniques that would enable Asia's agricultural systems to cope with climate change, while benefitting poor and vulnerable farmers. The study's recommendations ranged from improving the use of climate information in local planning and strengthening weather-based agro-advisory services, to stimulating diversification of rural household incomes and providing incentives to farmers to adopt natural resource conservation measures to enhance forest cover, replenish groundwater and use renewable energy. The United Nations Statistics Division, charged with collecting statistical data on global regions including Asia, publishes a classification standard, United Nations M49, which assigns code numbers to continental regions, areas and countries, based on statistical purposes, and the countries and regions grouped together don't imply any assumption regarding political or other affiliations between the grouped countries.