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2.1.2 Trend in Rainfall Changes
According to several studies that compare January rainfall on the period of 1980-2010 to the 1961-1990 baseline data, the change in the average rainfall value is not uniform for
Indonesia. The average rainfall for the period of 1980 – 2010 for most of Sumatra Island is increasing about 10-50 mm compared to 1961 - 1990. As for other areas, there are areas which
average rainfall value is increasing, but some are decreasing.
Examples of the results of rainfall trends analysis in January from GPCC data: a the average baseline value of 1961-1990 baseline and b the difference in the average value of the period
1980-2010 data until 2007 compared with the baseline Bappenas, 2010c.
2.1.3 Trend in Sea Level Rise
Data from Simple Ocean Data AssimilationSODA shows the characteristic of Indonesia’s sea level rise SLR with the 30-50 years pattern 1860-1910, 1910-1950, 1950-1990 or multi-
decade variations decadal. This data also shows that Indonesia’s SLR is about 0.8 mmyear and increasing to 1.6 mmyear since 1960 and then jumped to 7 mmyear in 1993.
Average SLR anomalous variations in Indonesian waters in 1860-2010, which
is calculated from SODA data full green line, ROMS-SODA red dashed line,
and altimeter blue dotted line. It also shown the linear trend lines calculated
for each data.
2.1.4 Trend in Extreme Weather and Climate Events
Extreme weather and climate events are an intrinsic part of the climate system that are irregular chaotic. On the other hand, climate change is allegedly has the potential to increase
the frequency of extreme events in various regions of the world. The trend of change in the odds of daily extreme rainfall based on CDF analysis of TRMM
satellite data indicates an increased chance of daily extreme rainfall in most parts of Indonesia,
National Action Plan for Climate Change Adaptation RAN-API - Synthesis Report
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except for some areas in Maluku colored blue, within a period of approximately 10 years ranging from 1998 to 2008 .
a CDF curve with a threshold value for highest 1 daily rainfall chances based on TRMM satellite data for the period of 1998-2008. b The distribution of value changes in extreme daily
rainfall chances in the TRMM data for the 2003-2008 period relative to the value of opportunities in 1998-2002 period.
2.2 Climate Change Projection Based on IPCC-AR4 Models
Climate projection result is highly dependent on the scenarios of increase in greenhouse gases GHGs concentration in the atmosphere which is based on the assumption of global
socio-economic development and the main technologies that support it. In the IPCC-AR4, the scenarios used are based on the Special Report on Emissions Scenarios SRES.
2.2.1 Projection on Increase in Surface Temperature
IPCC-AR4 models assume that the temperature rise is caused predominantly by the effects of GHGs spread evenly in the atmosphere, therefore the projected average increase in
temperature for the region of Malang in East Java can represent all regions in Indonesia. As shown in the figure, it can be said the projected increase in average surface temperature
throughout Indonesia due to GHGs until the period of 2020-2050 is approximately 0.8 - 1°C relative to recent climatic period in the 20th century Bappenas, 2010c.
Average surface temperature projections for the area of Malang,
East Java based on IPCC-AR4 model after going through downscaling
process. Showing also historical data from 1951 to 2010 and the results
of GCM model simulations for the 20th century and projections for the
three SRES scenarios B1, A1B, and A2. Monthly time series data was
first smoothed to show the long-term trend KLH, 2012a
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