At a time when global warming is threatening a rise in sea levels across the world, Silicon Valley giants Facebook Google and Cisco may be more concerned as their campuses are now at the risk of being flooded.

A fresh forecast by a team of scientists has warned that these companies face the prospect of their Silicon Valley headquarters becoming swamped by water as rising sea levels threaten to submerge much of the property in San Francisco Bay Area, The Guardian reported.

Even under optimistic scenarios where rapid cuts in greenhouse gas emissions avoid the most severe increases, the companies may face cut-off from others around the world, the team noted.

"Without significant adaptation, social media giant Facebook's new campus appears most at risk," the report added.

Facebook's campus at the San Francisco Bay shoreline is a 430,000 square feet complex - with a nine-acre garden rooftop - and is an extension of its Menlo Park base.

"Facebook is very vulnerable. They built on a very low site. I do not know why they chose to build there. Facebook thinks they can pay enough to protect themselves," Lindy Lowe, a senior planner at California's Bay Conservation and Development Commission, was quoted as saying.

The elevation that Facebook gave to its premises will not be sufficient from saving it from a 1.6-feet rise in sea levels by the end of the century.

The search engine giant Google located in Mountain View and technology company Cisco headquartered in San Jose may get some respite.

But should the Antarctic ice sheet disintegrate, the sea water will be pushed up beyond six-feet and swamp both.

"Even with a small increase, the sea comes into the 101 highway by the Googleplex and the whole areas could be screwed up," Kristina Hill, an environmental planning and urban design expert at the University of California-Berkeley, was quoted as saying.

"Google and Facebook will have to redo their campuses. I do not think there has been much success in getting Google to support adaption, it is not really on their radar," Hill added.

Nearly $100 billion (roughly Rs. 6,66,604 crores) worth of commercial and residential properties around the Bay Area are at risk from sea level rise and severe storms.