Super Typhoon Yolanda’s increased rainfall, intensity likely due to climate change - study

Climate change has been linked to the increased rainfall and intensity of Super Typhoon Yolanda (international name: Haiyan) that killed over 6,000 people in the Philippines in 2013, according to researchers from the World Weather Attribution on Thursday.

Researchers noted the increase in maximum winds during Yolanda’s onslaught.

One of the strongest tropical cyclones ever recorded, Yolanda ripped through most of the Visayas, particularly Leyte and Samar, on November 8, 2013, with sustained winds of up to 314 kilometers per hour.

“Using a ‘pseudo-global warming’ approach….the maximum winds from Haiyan were increased by 2 m/s relative to pre-industrial times (alongside similar increases for Typhoons Bopha and Mangkhut),” the new study read.

“Using a completely different approach, the stochastic storm model IRIS gives an increase of 3 m/s for Haiyan due to human-induced warming.”

It also generated storm surges of about 5 meters, with up to 7.5 meters peaks in some coastal areas in Tacloban City, Leyte, which accounted for some of the fatalities.

With this, the study said that the increase in Yolanda’s intensity also led to enhanced storm surges.

“[T]his analysis shows explicitly that if climate change did enhance the intensity of the storm, the storm surge also would have been enhanced,” it read.

“It is therefore with medium confidence that we can say that climate change increased the rainfall and intensity of Haiyan and, in turn, its storm surge, though quantifying this remains challenging.''

Further, researchers cited the accumulated cyclone energy during the 2015 typhoon season, two years after Yolanda’s onslaught, as being found to be connected to high sea surface temperatures in the eastern and central Pacific.

''In turn, it increased in likelihood significantly due to anthropogenic climate change,'' they said.

''More recently, the rainfall from Typhoon Gaemi (Carina in the Philippines) in Taiwan was found to have become about 14% more intense, while in the Philippines the observed increase was around 12%. Additionally, the wind speeds from Gaemi were enhanced by around 4 m/s.''

Yolanda injured nearly 30,000 individuals and displaced 4 million people as it destroyed over a million homes, especially in coastal areas.

“Haiyan underwent rapid intensification shortly before landfall, giving authorities limited time to adjust and roll out early actions, and because of the lack of hurricane-grade shelters, many of those evacuated were still in structures that were vulnerable to storm surges and strong winds,” the study said.

The study added that only a few people understood what a storm surge was, underestimating the severity of the impending flooding.

Deep poverty, unplanned coastal development, and the growth of informal settlements were also cited as factors behind the vulnerability and exposure to flood risk within the communities in Yolanda's path.

But the researchers noted the efforts by the Philippine government following Yolanda, such as crafting simpler warning messages for disasters, making earth blocks for shelter construction that can withstand natural disasters, and teaching residents to build biogas digester septic tanks to produce potable water.

The study focused on the 10 deadliest weather events in the International Disaster Database since 2004: three tropical cyclones (including Yolanda), four heatwaves, a drought, and two floods.

''To quantify the effect of human-caused warming on the weather events, scientists analyzed weather data and climate models using peer-reviewed methods to compare how these types of events have changed between a climate with human-caused warming and the cooler pre-industrial climate,'' the World Weather Attribution said. —VBL, GMA Integrated News