Fidelis E Satriastanti Jakarta Globe 11 Aug 10;
A recent study showing sea level rise and shifting rain patterns in West Nusa Tenggara should not be used as evidence of climate change, its authors warn.
The study, published this week by the Environment Ministry and the German Society for Technical Cooperation (GTZ), was undertaken to assess the vulnerability of small islands to the impact of climate change, and was conducted on Lombok and Sumbawa.
It showed there was a rise in sea levels of up to eight millimeters between 2008 and 2009 on the southern coasts of the islands.
The study also found that the peak of the rainy season, which from 1961 to 1990 was usually in January, has fluctuated between December and February in the last two decades.
Tri Wahyu Hadi, a professor of atmospheric sciences at the Bandung Institute of Technology (ITB) who took part in the study, said that while the initial conclusion was that these changes were brought about by climate change, the lack of long-term data made it impossible to offer a final scientific judgement.
“We’ve already answered the first question, whether there has been any change,” he said. “The next question is, how much have these parameters changed? That’s a difficult one to answer,” he said.
“Take, for instance, the fact that it’s supposed to be the dry season now. Yet it continues to rain. But can we really attribute this to climate change rather than a weather anomaly?”
Tri cited research that had been conducted in Indonesia in 1929 by Dutch scientist Cornelius Braak, who wrote: “In some years the farmer will wait in vain for the dry season, whereas in other years he will look out for months and months for the first good shower.”
“That means that we’ve been experiencing weather anomalies for a long time now,” Tri said. “The next question is whether these anomalies are arbitrary or part of a wider pattern.”
He said a comprehensive study of parameters affected by climate change, such as temperature, precipitation and wind, would ideally require a body of records going back several decades, which was unavailable for the West Nusa Tenggara study.
The World Meteorological Organization stipulates that any such study would require 30 years worth of data for the control period and 30 years for the test period.
“We couldn’t get records dating that far back, a minimum of 60 years,” Tri said. “We did, however, get data from 1961, and we used the period from 1961 to 1990 as our baseline for the years from 1991 to 2007.”
He added that this data showed that even in the pre-1990 control period, the peak period for rainfall in Lombok occasionally fell outside of January.
There is thus no conclusive case for climate change based on this data, Tri said, adding that the only conclusion that could be drawn was that rain patterns in Lombok varied significantly.
“If you really want to test for climate change, you need to have 30 years of data after the control period,” he said.
“The issue of whether what we’re seeing is climate change or a number of weather anomalies is a secondary one. The real point is that climate patterns can be unpredictable.”
However, Sulistyowati, the assistant to the deputy for climate change impact control at the Environment Ministry, said the study was conclusive proof of climate change, regardless of the WMO criteria.
“It found changes in rainfall patterns and intensity, all of which point to climate change,” Sulistyowati said, adding that a 10-year body of data was sufficient to convince her.
Ibnu Sofian, an oceanographer from the National Coordination Agency for Surveys and Mapping (Bakosurtanal), said the increased frequency of rough seas around Indonesian islands was proof of global warming, the lack of data notwithstanding.
“The rise in the sea levels comes from global warming, which has a direct impact through thermal expansion and leads to the melting of ice at the polar caps,” he said.
“Meanwhile, climate variability such as La Nina and El Nino can also affect sea levels, precipitation and sea surface temperatures,” Sofian said.
