2. Research background2.1 Indonesian climate: Past and projectionsThis section explains historical climate and future climate in Indonesia and West Nusa Tenggara such as historical and projections of precipitation and temperature. This section also explains evidence that climate change has occurred in Indonesia and West Nusa Tenggara. If the temperature or rainfall change between the baseline and the recent period is statistically different, this means that climate change has occurred. Otherwise, climate change does not exist. Statistics shows that Indonesia has experienced increasing temperature but insignificant rainfall change since the mid-20th century. The annual mean of Indonesian rainfall in the period 1950-1979 was about 2832296 mm/year and in the current period 1980-2009 was about 2786272 mm/year. The difference of the annual mean rainfall between the periods is statistically insignificant. Likewise, the Indonesian mean temperature during 1950-1979 was about 25.60.17oC, while the mean temperature in the period 1980-2009 was about 26 0.160C. Thus, Indonesia has experienced climate change as temperature change is statistically significant between the periof 1950-1979 and the period 1980-2009.In case of the projection of temperature, figure 1 shows that Indonesia is projected to experience higher temperatures in future. According to IPCC (2013), Indonesia is projected to experience an increase of mean temperature in the range of 0.3-1.2oC by 2035 and in the range of 0.8-2.7 oC by 2100. Temperature in wet seasons (December-February) and dry seasons (June-August) is projected to experience a similar increase.

Figure 1. Median projected temperature change in December-February (top) and June-August (bottom) relative to the period 1986-2005 for RCP (Representative Concentration Pathways) scenario 4.5 based on an ensemble of CMIP5 model projections. From left to right is the period 2016-2035, 2046-2065 and 2081-2100 (IPCC, 2013).As shown in figure 2, Indonesia is projected to experience mixed and relatively insignificant rainfall change (IPCC, 2013). Total Indonesian rainfall is projected to change between -1% and 13% by 2046 and between -2 % and 18% by 2100. The average projected decrease of rainfall in southern Indonesia (including West Nusa Tenggara) is about -5% by 2100. However, the magnitude of projected changes is not expected to exceed that of natural decadal variability over much of Indonesia.

Figure 2. Median projected rainfall change in October-March (top) and April-September (bottom) relative to the period 1986-2005 for scenario RCP 4.5 based on an ensemble of CMIP5 model projections. From left to right is the period 2016-2035, 2046-2065 and 2081-2100. The hatched area denotes the area where the 20-year mean differences of the percentiles are less than the standard deviation of model-estimated present-day natural variability of 20-year mean differences (IPCC, 2013).

Data for Indonesian rainfall and temperature is from KNMI climate centre ( HYPERLINK "http://climexp.knmi.nl/" http://climexp.knmi.nl, CRU reanalysis)

All statistical tests to test temperature and rainfall change are based on t-test (the significance level is 0.05). Furthermore, statistical tests for temperature and rainfall variability are based Levenes tests (the significance level is 0.05)

RCP 4.5 is a climate scenario with a stable radiative forcing at 4.5 Watts/m2 in the year 2100. RCP=Representative Concentration Pathways.

Southern Indonesia is influenced by Australian Maritime Monsoon that leads to a lower rainfall while northern Indonesia is influenced by East Asian and Indian Monsoon that lead to a higher precipitation (IPCC, 2013).

Decadal variability is climate variability for the period for decades

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