Indonesia
as a country in the tropics made up of thousands of island experiences climate
pattern changes. The impact of climate change in Indonesia’s territories is
marked by the climate pattern change in which there is a shift to the start of
a season. Some areas experience delayed in beginning rainy season and beginning
of dry season. The change in the beginning of the season is not consistent in
all areas in Indonesia. Some areas even experience early change of season. The
current rainfall intensity also differs from those of previous years.
Currently,
there is a tendency for larger divergence between the rainfall intensity during
rainy season and the rainfall intensity during dry season, and sometimes the
divergence in intensity is really extreme. The incidents of flood, drought and
landslide are proofs of the climate change phenomena caused by the change of
rainfall intensity in Indonesia. These incidents certainly impact the
development process in the affected regions.
The
other major threat as result of climate change impact in relation to Indonesia’s
geographical condition is sea level rise. The threat of sea level rise and
islands subsidence into the sea in the future will be made worse by the
incident of high sea waves along the coastal areas, especially during the
transitional season. Other review in support of above-mentioned IPCC
(Inter-Governmental Panel on Climate Change) report states that with the sea
rise of about 1 meter, it is estimated that 405.000 hectares of coastal areas
including small archipelago will be flooded.
A.
The
Rising of Indonesia’s Sea Level Temperature
Based
on the global simulation model of A2 scenario1, the average temperature change
in Indonesia in 2100 will rise 30C relative to the average temperature in 1990.
Such temperature rise is still lower compared to the global temperature rise
which will reach 60C in 2100. However, Indonesia’s geographical condition as an
archipelago will generate more dynamic atmosphere condition in Indonesian
territory which will affect the rainfall pattern change. The highest
temperature change anomaly will take place in Borneo region with the potential
of a more widespread drought. Furthermore, in several regions with high
temperature anomaly, there is potential for increased condensation due to the
areas being surrounded by the ocean. For instance, in the region of Nusa
Tenggara, it is forecasted that there will be temperature anomaly of 2.7 –
2.90C in 2100 with the potential of increased level of rainfall intensity in
those areas (Figure 1).
 |
| Figure 1. Projected Change of Average Temperature in Indonesia in 2100 based on scenario A2 |
B.
The
Change in Rainfall Intensity and Pattern in the Islands of Indonesia
The
change in regional climate pattern due to global warming is affecting the local
rainfall pattern. Such change is setting in motion the potential danger of the
tendency of high intensity rainfall during wet months and low intensity
rainfall during transitional months. This condition will be even worse in the
future by 2080s. Based on analysis conducted in Java – Bali regions, West Java
is the most vulnerable region under such extreme condition
The
result of analysis conducted by Boerdan Faqih (2004) using the monitoring
results from the existing 210 rain stations as well as the comparison with the
current averagerainfall intensity trend, it is noted that there has been trend
of dwindling rainfall intensity in Java, Lampung, South Sumatera, South
Sulawesi and Nusa Tenggara. On the other hand, the trend of increasing rainfall
intensity is found in Borneo and North Sulawesi (Figure 2).
 |
| Figure 2. Projected Change of Rainfall in the Month of January |
C.
Indonesia’s Sea Level Rise
The
increase in the Greenhouse gases concentrate which affects global warming will
indirectly affect the sea level rise through a process called thermosteric. The
increase of Greenhouse gases concentrate is responsible for sea level
temperature rise. The sea level temperature rise affects the expansion of sea
water volume, whereby each degree Celcius increase will cause the sea level to
rise by 0.2 – 0.4 m (Knutti et al, 2000). Furthermore, the sea level
temperature rise will also have an affect on the defrosting of glaciers and
icebergs
in
Greenland and the Antartics. Indonesia’s sea-water territory has been
experiencing sea level rise trend averaging 0.6 – 0.8 cm/year.
 |
| Figure 3 . Estimated Sea Level Rise in Indonesia Oceans Based on the Dynamic Increase of Ice Melting Model Post IPCC AR4 |
Based
on Figure 3, Sea Level Rise will reach 175 cm in 2100 relative to the Sea Level
Height in 2000. Meantime, Sea Level Height will rise by 52.5 cm in 2030, will
rise by 87.5 cm in year 2050, and will rise by 140 cm by 2080. This trend
elevates the increase of abrasion, erosion and sea water inundation, which is
not only caused by the Sea Level Rise, but also by the storm wave, high and low
tide by the moon’s and sun’s gravity, as well as the extreme climate such as La
Nina which is modulated by the high Sea Level Rise.
Moreover,
the inconsistent Sea Level Rise in Indonesia, whereby the rise in Pacific
Ocean’s level is greater than that of Indian Ocean, has effects on the seasonal
flow pattern, Indonesia Through Flow (ITF), the increase in erosion, the change
of coastal line, and the reduction of wetland ecosystem. The change of ITF
affects the regional climate change pattern in Indonesia such that the local
rainfall pattern also changes. Besides, the reduction of wetland ecosystem will
impact the coastal ecosystem and as well as increases the intrusion of sea
water into the coastal aquifer.
