Climate change not sole cause of weather-related disasters

What is happening to the weather in South-east Asia and the larger Asia-Pacific region?

In the past month alone, severe floods have battered Malaysia, Indonesia, Thailand, the Philippines and Sri Lanka, forcing more than a million people from their homes and killing about a hundred people so far.

The floods were the worst in decades, causing nearly RM1 billion (S$378 million) in estimated damage in Malaysia alone.

In Australia, soaring temperatures - forecast to top 40 deg C in some cases - have contributed to wildfires raging across parts of the country. The ongoing blazes east of South Australia's capital Adelaide are the worst in more than 30 years, prompting the government to declare a major emergency.

Even the fatal crash of Indonesia AirAsia Flight QZ8501 has been partly attributed to extreme bad weather.

Indonesia's Meteorology, Climatology and Geophysics Agency issued a 14-page report last week, saying weather data suggests the jetliner flew into storm clouds, causing icing and damage to the engines. The document also noted "worrying conditions" on the plane's route from Surabaya, Indonesia, to Singapore.

In the wake of all these disasters, government officials and some experts have pointed to climate change as the cause. They are likely to be right, but only up to a point.

Global warming has caused average temperatures to rise, which can lead to heavier downpours, as warmer surface temperatures allow the air to be more saturated with water vapour.

This is why you can sometimes see water vapour in the air after a hot shower.

The warming has also melted glaciers, polar ice caps and ice sheets more quickly than usual, causing sea levels to rise. Water itself expands when it heats up, contributing to the higher levels.

The rising waters can cause low-lying areas to be overwhelmed, and prevent drainage systems from pushing water out to sea efficiently, especially during high tides, leading to floods.

While these long-term changes may be incremental, they could coincide with other weather events to cause an onslaught of disasters like the recent ones.

The Philippines, for example, was hit by Typhoon Hagupit, while the Malaysian Meteorological Department (MMD) has blamed a moon-related phenomenon. When the Moon is closest to the Earth, a position known as perigee, its gravitational pull can create higher tides, though some experts say the impact is limited.

The MMD said the Moon was at perigee on Dec 24 at 16.44 GMT (12.44am on Dec 25 here).

Rainfall data for the flood- stricken nations shows heavier- than-usual storms in the past month. More long-term data is needed to establish whether this is part of a trend or a fluke.

The MMD's spokesman, Dr Mohd Hisham Anip, said that in a "normal" December, rainfall averages from 500mm to 600mm for the country's east coast.

"But areas such as Kuala Krai in Kelantan, Kuantan in Pahang and Gong Badak in Terengganu received more than 1,000mm of rain" last month, he said.

Indonesia was plagued with the same extreme weather.

While the December rainfall data is not available yet, areas overwhelmed by floods were forecast to receive up to twice the usual amount of rain.

Thailand, Sri Lanka and the Philippines were also struck by unusually heavy downpours.

Singapore has also been experiencing more, and more intense, storms in the past three decades.

But some experts said man- made problems also contributed to the floods.

Indonesia's National Disaster Mitigation Agency said population growth, urban development and environmental pollution contributed to the country's floods.

Land development and deforestation can cause more soil erosion during storms. The soil and mud are washed into rivers, making them shallower and more prone to overflowing over time.

Each year, up to 500,000 cu m of mud settles in the Citarum River basin, according to the Citarum Management Centre. The river is the largest and longest in West Java, Indonesia, which has been hit by floods.

The non-government Centre for Environment, Technology and Development Malaysia (Cetdem) also singled out improper drainage, and poorly planned and managed urban development for Malaysia's floods.

"Even if we are getting more floods due to heavier rainfall, our drainage system has not been up to par with the development that is taking place," said Cetdem executive director Anthony Tan.

Thai Prime Minister Prayut Chan-o-cha admitted Thailand's floods were exacerbated in some areas, as roads were built without drains in natural floodways.

In several of the countries, experts have also blamed people who dump rubbish into rivers for contributing to the floods. Several of the flood-stricken countries have vowed to investigate causes of the floods and improve their drainage systems.

The Intergovernmental Panel on Climate Change has warned that, for Asia, climate change could mean higher risks of coastal and urban flooding, more deaths due to warmer temperatures and drought-related water and food shortages.

Going by last month's disasters, the sooner each country faces up to this reality and works to prevent it, the better.

zengkun@sph.com.sg

This article was first published on Jan 05, 2015.
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