East Asia has been hit by an unusually intense run of typhoons, with El Niño warming the Pacific and influencing storm tracks and strength. Scientists warn that warmer conditions could make the storms even more dangerous: simulations of major Philippine storms found that higher temperatures increased total accumulated rainfall by 26%, adding to risks from flooding, crop losses and infrastructure damage.
Wild weather is a way of life for people living along the coasts of the Philippines, Taiwan, China and Japan. But the last few months have been extraordinary.
A wave of intense and, at times, unpredictable storms, exacerbated by the El Niño weather pattern, has killed dozens of people, closed major airports and destroyed crops and infrastructure across a wide area of East Asia.
In October, almost all of Taiwan shut down as Typhoon Champi, a storm large enough to engulf the island of 23 million people, approached its north-eastern coast. With winds of 295km/h (193mph), it was equivalent to a category five hurricane and had the potential to flatten homes and generate destructive waves.
Fortunately, Champi did not make landfall in Taiwan. It passed the island while bringing heavy rain, but its effects were felt much farther afield. Hundreds of flights were cancelled in Hong Kong, Taiwan and Japan. In the Philippines’ Batanes archipelago, coastal highways were closed as huge waves struck the shore, while power was cut to 15,000 homes in Japan’s southern Okinawa islands.
How El Niño is influencing the storms
El Niño is a naturally occurring climate phenomenon in which warm water gathers in the eastern Pacific and changing wind patterns help drive extreme weather around the world.
It occurs roughly every two to seven years and usually lasts about a year. The current El Niño, which the UK Met Office has forecast to be the “strongest in living memory”, is expected to continue until February or March.
In June, Japan saw Typhoon Mekkhala and Severe Tropical Storm Higos move towards its eastern coast at the same time, prompting one million people to evacuate. In July, Tropical Storm Narra passed along China’s southern coast near Guangxi, submerging villages and displacing tens of thousands of people.
August brought Super Typhoon Dolphin, which travelled across the Pacific for 16 days before striking eastern China. It caused severe flooding and dozens of casualties. Later that month, Typhoon Saudel made landfall in three south-eastern Chinese cities over the course of a week, disrupting transport networks and forcing thousands of people to evacuate.
The Pacific Ocean has been heated to record levels by El Niño and is now carrying unusually high levels of energy for typhoons, according to the Accumulated Cyclone Energy (ACE) measure. ACE records the combined intensity of storms over a season. This year’s ACE value for South-East and East Asia is forecast to be nearly twice the 30-year average.
El Niño also changes wind patterns, causing typhoons to form farther east than usual. That means they can spend longer over warm water, allowing them to become stronger.
Record ocean temperatures
“The Pacific can be likened to someone ‘burning with fever’,” said Ana Liza Solis, head of climatology at the Philippines’ national weather bureau. “It can go into convulsions soon,” she told a press briefing in Manila in September.
Forecasts suggest the worst may not be over. Last month, sea-surface temperatures in the equatorial Pacific — the area monitored by the Japan Meteorological Agency for its El Niño predictions — reached 4C above normal. That was the highest level since records began in 1949. The previous record, 3.6C, was set in December 1997.
China’s climate agency has warned that sea-surface temperatures could continue to rise over the next three months because of El Niño.
Typhoon season usually peaks around September and October, but the prospect of continuing ocean warming is raising concern across a region already battered by storms arriving one after another.
“Very, very scary” simulations
In August, Typhoon Chan-Hom surprised storm watchers in Japan by crossing the country from east to west rather than following the more usual south-to-north path. Japan’s well-resourced and well-prepared authorities were able to evacuate people quickly, but similar action would be much more difficult in some neighbouring countries.
To examine how rising temperatures could increase the danger, Manila-based climatologist Rafaela Jane Delfino and her colleagues simulated the effects of warmer conditions on some of the Philippines’ most recent major storms. Their analysis included 2013’s Super Typhoon Haiyan, known in the Philippines as Yolanda, which killed more than 6,000 people.
The researchers found that higher temperatures increased total accumulated rainfall by 26%. Delfino described the results as “very, very scary findings”.
The prospect is particularly serious for the Philippines, where flooding from monsoon rains and about 20 tropical storms a year has become one of the country’s main disaster risks.
In recent years, floods have brought entire cities to a standstill for days. Frustrated by the annual disruption, Filipinos have taken to the streets to protest against corruption. They say it is draining millions of dollars from flood-control projects.
In an article published on the University of the Philippines website, Delfino argued that leaders and officials must develop a better understanding of climate hazards if communities are to prepare effectively.
Preparing for the impact
Countries across the region are taking steps to limit the immediate effects of the storms. Japan has urged people to stockpile food and essential supplies for typhoon season and to secure outdoor furniture that could become dangerous projectiles in high winds.
China has asked local officials to identify vulnerable areas and is upgrading its storm-warning and monitoring systems.
The Philippines and neighbouring countries in South-East Asia are preparing for disruptions to food production, particularly rice. They have also increased support for farmers, including by providing fertiliser.
However, the long-term consequences remain less certain. The window for governments to act on El Niño is “closing”, the United Nations Development Programme in Asia and the Pacific said recently.
“How severely a community experiences an El Niño is decided years in advance, by where roads and settlements are built, how water is managed, who is covered by social protection and whether public budgets have room to absorb a shock,” it said.
“Every El Niño tests the resilience we have built; this one should also drive us to build more.”
Source: www.bbc.co.uk