How better to mark this year’s Earth Day than to remind ourselves of the existential perils of climate change. As the Earth warms, polar ice melts, sea-levels rise. As sea-levels rise, low lying coastal lands submerge. Much of coastal Florida would disappear under a sea-level rise of a mere 6 feet.

Our tech innovation hub in Silicon Valley wouldn’t fare well either. Many of our tech giants, including Google, Facebook, Oracle, Cisco and Salesforce, have planted their roots on the bay-side of Silicon Valley. Much of this area is only a handful of feet above sea-level. Oh, and kiss goodbye to San Francisco International Airport as well — though perhaps the local VCs could re-purpose it into a sea-plane terminal.

The map above, courtesy of National Oceanic and Atmospheric Administration (NOAA), highlights the flood prone areas in shades of blue.

From the Guardian:

Technology giants including Facebook and Google face the prospect of their prestigious Silicon Valley headquarters becoming swamped by water as rising sea levels threaten to submerge much of the property development boom gripping San Francisco and the Bay Area.

Sea level forecasts by a coalition of scientists show that the Silicon Valley bases for Facebook, Google and Cisco are at risk of being cut off or even flooded, even under optimistic scenarios where rapid cuts in greenhouse gas emissions avoid the most severe sea level increases.

Without significant adaptation, Facebook’s new campus appears most at risk. The 430,000 sq ft complex – topped with a nine-acre garden rooftop – is an extension of its Menlo Park base and was crafted by architect Frank Gehry. Located near the San Francisco Bay shoreline, the offices are designed to house 2,800 staff.

“Facebook is very vulnerable,” said Lindy Lowe, a senior planner at California’s Bay Conservation and Development Commission. “They built on a very low site – I don’t know why they chose to build there. Facebook thinks they can pay enough to protect themselves.

“The temporary flooding within the campus can probably be addressed, but the temporary flooding onto the roadway can’t be addressed by them. I think they realize that is the weakest link for them. We’ll see how dedicated they are to that facility.”

Facebook has elevated its office to spare it from flooding, but even with a 1.6ft rise in sea levels by the end of the century – which is towards the lower end of projections – the area around it will be inundated. Much sooner, within the coming decades, the roads leading into the complex will flood so regularly that major adaptions will be required to keep the site viable. Facebook didn’t respond to repeated requests to comment on the issue.

The situation is a little better for Google, located in Mountain View and also unwilling to discuss sea level rise, and Cisco, headquartered in San Jose. But should the Antarctic ice sheet disintegrate, as outlined in a recent scientific paper, seas will be pushed up beyond 6ft and swamp both businesses.

The situation is similarly stark for Salesforce, which would see its San Francisco base submerged under the worst sea level rise scenario. Meanwhile, Airbnb, located near the vulnerable Mission Bay area, will have its headquarters gain a much closer bayside view simply by staying put.

Read the entire store here.

Image: Sea-level rise and coastal flooding impacts, San Francisco / Bay Area map. Courtesy of NOAA.