Global heating and other human activity are making Asia’s floods more lethal | Extreme weather

Families stranded on their roofs. Houses buried by rapidly flowing mud. Jagged brown craters scarring the green hillsides.

These scenes were the result of a series of cyclones and storms during a strong monsoon that hit Asia with torrential rains, destroying critical infrastructure and reshaping landscapes. Severe weather has killed at least 1,200 people in the past week and forced millions more to flee without knowing whether their homes will still be standing when they return.

The fallout marks a grim escalation of deadly weather conditions in the region, made worse by the planet-warming blanket of carbon pollution. A study by the Intergovernmental Panel on Climate Change (IPCC) predicts that South and Southeast Asia will experience more intense rains as temperatures rise, with a “sharp increase” in the frequency of floods hitting monsoon regions.

Roxy Koll, a climatologist at the Indian Institute of Tropical Meteorology and co-author of the latest IPCC report, said the behavior of cyclones had changed more than their numbers this season. “They are wetter and more destructive because the background climate has changed,” he said. “Water, not wind, is now the main driver of disasters. »

Natural weather conditions, including a La Niña cycle and a negative Indian Ocean dipole, helped create the conditions for storms to form. Scientists haven’t determined how much pollution from global warming has contributed to the death toll, which continues to rise with floodwaters, but they have long established that warmer air retains more moisture — about 7 percent per degree Celsius.

The extra water, combined with increased energy from warmer oceans, leads to the formation of much more powerful storms.

“Across South and Southeast Asia, this season’s storms brought extraordinary amounts of moisture,” Koll said. “A warmer ocean and atmosphere are loading these water systems, so even moderate cyclones now trigger rainfall that overwhelms rivers, destabilizes slopes and triggers cascading disasters.

“Landslides and flash floods then hit the most vulnerable, the communities living along these fragile environments. »

Rains have loosened soils and leveled slopes in mountainous areas, wiping out villages and rendering roads and railways unusable. The floods also hampered relief efforts by disrupting electricity supplies and telephone networks.

In Indonesia, where freshly cut logs washed up in flooded parts of the country that also suffer from deforestation, the damage was reportedly made worse by the felling of trees that could have absorbed water and stabilized the soil. The attorney general’s office is leading a task force investigating whether illegal activities contributed to the disaster, according to local media. Reuters also reported that the Environment Ministry plans to question logging, mining and palm plantation companies about their activities.

Sonia Seneviratne, a climatologist at ETH Zurich and co-author of the latest IPCC report, believes that other human factors could have amplified the extent of the flooding, but this does not contradict the role of climate change in worsening rainfall.

“We have a very clear signal of increasing heavy precipitation with increasing warming, both globally and in Asia,” she said. “The influence of human-caused climate change on the intensification of heavy rainfall is well established, and it is a key driver of reported flooding. »

The long-term good news is that the human cost of floods and storms has fallen sharply around the world, as governments have put in place early warning systems and gotten used to getting people out of harm’s way before a disaster strikes. Even in middle-income countries that have made great progress in transforming death tolls into displacement figures, experts say response systems are still patchy.

“The picture from Southeast Asia shows that we still need even better early warning systems, even better shelter for people in case of floods… [and] even more nature-based solutions – planting trees and mangroves in places particularly at risk of flooding to keep people safe,” said Alexander Matheou, director of the Asia-Pacific region of the International Federation of Red Cross and Red Crescent Societies.

People also need “better social protection systems during disasters, so they can immediately get the money, food, medicine and shelter they need when disaster strikes,” he said.