Rain and floods: managing the human footprint

There was no storm over Manila in the second week of August. But why was there so much rain?  Why was the flooding so severe?

When it comes to tropical cyclones, the Philippines sits within the planet’s “ground zero.”  So, it is to be expected that these “generators” of violent weather will continue to exert a dominant influence on our national climate. Yes, the storm was near Japan. These typhoons, however, generate the forces that drive and enhance other weather systems such as the southwest monsoon—i.e., habagat.  In combination, these two systems serve as the “delivery system” for wind, moisture and extreme weather. This will continue. A landmark WWF study on the Coral Triangle and climate change, released in 2009, says that storms are likely to intensify.

Historically, most typhoons entering the Philippines come from the Pacific Ocean. Over the last four years, however, we have seen extreme weather systems develop in the West Philippine Sea. Although this was not a frequently recurring situation 10 or 20 years ago, the West Philippine Sea is now occasionally warm enough to be a spawning area for a phenomenon called tropical cyclo-genesis—i.e., the birth of storms. The province of Pangasinan has experienced this, first hand.  With global warming, we should not be surprised if this is happening. If we accept all this as plausible, then we should not be surprised to see “enhancements” of other weather systems that come from here, such as cyclones, low-pressure areas and the southwest monsoon.  This will probably continue as well. The WWF study says that this is likely to become more frequent.

So, why was the rain so heavy over Metro Manila?  We have dealt with the southwest monsoon as far back as anyone can remember.  After all this time, what has changed? This involves a third development called “the urban heat island effect.”  This is not due to climate change. Like land subsidence from excessive groundwater extraction, this is due to human activity—poor planning, political gridlock, inadequate or inappropriate urban management, inadequate implementation of zoning rules and land use plans, and haphazard real estate development, among others.  This time, many of the problems have to do with management.

Like most megacities in Asia, Metro Manila has adopted the long outdated Western development model referred to as “the urban sprawl.”  Megacities that extensively convert porous and water-absorbent land to impervious expanses of concrete generate a tremendous amount of heat. When land conversion and real estate development are allowed to grow in a haphazard manner, it only makes things worse. “Urban heat islands” are aggravations that intensify the water cycle. They are “magnets” that draw in and enhance weather systems such as cyclones, low-pressure areas and the monsoon.  In some cases, they have been known to spawn local tornadoes.  We saw that right in Quezon City just last year, where seven barangays were reported to have been badly affected.

This is not rocket science. There have been many studies made of Asian cities—such as Beijing, Tokyo, Mumbai, Kuala Lumpur and Kyoto—all investigating this specific phenomenon. These studies are all freely available on the Web. Essentially, all of them have come to the same conclusion. Large urbanized cities, especially when poorly planned and managed, tend to create “heat islands” that serve to aggravate weather impacts.  In a climate-defined future, these emerge as zones of concentrated risk.  Will this continue?  Will it get worse?  Well, this time, it’s up to us. Only humans can manage the human footprint.

Climate change changes everything.  Humankind created it. The haphazardly built megacities of Asia are aggravating it. Metro Manila’s garbage mess and woefully inadequate transport system just make it worse. We started it. We can stop it. But let’s stop pointing fingers at the monsoon. As a nation, we have to stop talking ad nauseam, and start moving forward on workable solutions.  The solutions will be complex, and so they must be conducted in an integrated manner.  Some of the decisions will not be easy.  But we have no choice. We only have one Philippines, and one planet.

Jose Ma. Lorenzo Tan is vice chair, president and CEO of World Wildlife Fund (WWF) Philippines. He also serves as chair of the Philippine Tropical Forest Conservation Foundation. He has written and published a number of books, including “The Last Great Forest” and “A Field Guide to Whales and Dolphins in the Philippines,” which both received awards.