The record-breaking amount of rainfall brought by Tropical Storm “Ondoy” that inundated large parts of Metro Manila in less than 24 hours on Saturday could happen again, a climatologist warned Monday.

Flaviana Hilario, a climatologist at the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA), said the unusually high amount of rainfall caused by a single weather disturbance will happen more often in the next years due to climate change.

Hilario clarified that the 455 mm of rainfall that was dumped in a 24-hour period at the PAGASA weather station in Science Garden, Quezon City on September 26 will most likely not become just an isolated incident.

“When we say that this was a manifestation of a changing climate, we meant that disturbances will start to surpass extreme values, which will happen more often and not in just one event. In the advent of climate change, we expect heavier rains like this,” Hilario told the Manila Bulletin.

“Rains will definitely be heavier than the volume of rainwater that we usually expect to come in the past. But the difference in the amount of rainfall would depend on the year if we are looking at 2020 or 2050,” she added.

Hilario, who also heads the Climatology and Agrometeorology Division (CAD) of PAGASA, suggested
the improvement of drainage system in the National Capital Region and neighboring provinces like Bulacan, which are considered flood-prone areas because of their flat terrain.

She added that the floods spawned by Tropical Storm “Ondoy,” which killed less than a hundred people and is considered as the worst flood in Metro Manila in four decades, should serve as a wake-up call to Filipinos to change their ways that contribute to global warming.

Over the weekend, Tropical Storm “Ondoy” dumped rains that were heavier than the 344 mm of rainfall recorded in Quezon City on June 7, 1967.

Other researchers also claimed that the amount of rainfall brought by the storm over Central and Southern Luzon particularly Metro Manila on September 26 and 27 was greater than the amount of rains brought by Hurricane “Katrina” that devastated New Orleans in 2005.