Bangkok (pop. 9 million, 13 million in the metropolitan area) is one capital city and metropolis which will be affected by rising sea levels and likely need to move at some point in the 21st century. This is not a new idea, and most recently, the Indonesian goverment announced the intention to begin migrating their capital from Jakarta to a new location on the island of Borneo, beginning at the end of 2020. This won't save Jakarta in general, whose woes will continue in terms of sea-level encroachment, massive land degradation and pollution issues, and a huge and growing population.
The Thai prime minister, not one known for clear thinking, has simply mimicked (as possible) the move of a capital. However, the way in which he discussed it doesn't take into account the vast and multi-faceted threat to the city. Relocating the capital (that is, the government administration) to the outskirts of the city won't fix anything, nor will relocating the government to yet another city. The idea that Bangkok itself will no longer exist without massive expenditure and engineering hasn't penetrated that thick pate.
Looking to other regional cities at great risk from a rising sea-level:
- Phnom Penh, Cambodia (pop. 2 million)
- Ho Chi Minh City, Vietnam (Saigon) (pop. 9 million)
- Yangon, Myanmar (Rangoon, Burma) (pop. 5 million)
Combined with Jakarta (pop. 9 million), there are some 30-40 million people who will be impacted in some way, though it will start with the lowest-lying areas first. The real question is whether or not a government faced with rapidly deteriorating situation will be able to have the resources (including brains and a plan, as well as men and money to do the building/relocating), and the time to have an orderly retreat from the sea.
Jakarta Problem and Solutions
Besides sea-level rising, Jakarta itself is sinking, from 1-15cm/year, largely due to water extraction. The current solution is not really a solution, but should help somewhat. This is the construction of a dike (and toll road), which would also allow for the start of land reclamation in Jakarta bay.
Seawalls have long been used as solutions to sea encroachment. However, until the root causes are addressed, this is only a holding action against a sea that will not be forever denied.
Bangkok Sea Encroachment and a Water Crisis
When the sea-level rises in Bangkok, the fresh water aquifier is at risk, and fresh water must be pumped to keep out the salt water from this resource. This means a substantial loss of fresh water (though of course saving the rest) as well as energy costs. At some point, this tactic to delay salt-water encroachment will fail, and it will become less and less viable to do so.
Groundwater pumping is itself a cause of Bangkok sinking, which it has been doing for some time.
Bangkok Structural Destabilization
While there are always options such as the Dutch have deployed to keep out the sea, and in fact reclaim land, this has taken hundreds of years of persistent and increasing technology from a people dedicated to, and whose survival depends on accomplishing this task. Bangkok is much more problematic in that respect. A massive seawall project would simply be unfeasible as soft mud is not something one can erect a modern metropolis upon. One must give credit to those thinking of how to develop a win-win situation, and indeed that kind of thinking is needed. However, yet another obese sprawl is not a solution, is indeed already the problem (besides global warming).