5000 years before 200 foot rise.

It's 216 feet, not 200 feet.

So says the latest National Geographic magazine regarding how much sea level would rise if all ice on Earth melted. No word if that includes ice cubes in your freezer.
Image: National Geographic. Art: Nick Kaloterakis
A little over a year ago Burrito Justice and I imagined what San Francisco would look like with 200 feet of sea level rise. Written brilliantly by Mr. Burrito, he imagined an AP news article about the rising seas. It created an archipelago in San Francisco.

Well we may have been off a bit, according to the National Geographic,

"There are more than five million cubic miles of ice on Earth, and no one really knows how long it would take to melt it all. Probably more than 5,000 years, some scientists say.

[The maps here show] all the ice on land has melted and drained into the sea, raising it 216 feet."

In fact it's uncertain what the exact maximum height would be due to so many factors involved: how much ice is there really, how much will thermal expansion of water take up in volume, will folks be around to keep some ice in the freezer? There's also no mention in the main article, "Rising Seas" on how they arrived at 216 feet.

Image: Burrito Justice/Urban Life Signs
The article covers many of the issues regarding sea level rise and how Superstorm Sandy was a wakeup call to many. What was interesting was the amazing fold up pull out map showing the ENTIRE WORLD flooded up to 216 feet. The most impressive was seeing Antarctica with no ice, and really looking like a smallish continent with many islands around it. That said, if the ice did melt, much of Antarctica would rise over millenia, much as the Canadian plains and northern Europe has over time since the load of ice was removed after the last ice age.
Image: National Geographic

The places hit the worst are a great list of the most populated places around the world:
  • The northern coast of Europe (maybe even goodbye Paris!)
  • All of populated Iraq
  • Much of China from Shanghai up to Beijing
  • The Eastern Seaboard of America
  • Of course Bangladesh and Florida
Sadly, the map of North America doesn't get detailed enough to show what San Francisco would look like. There would be a great Central California Sea, much as there would be at 216 feet. However, Chowchilla and Folsom would probably be underwater, unlike at 200 feet.
Image: National Geographic
This sea actually existed the last time all the ice in the world melted. Yes that's right. The planet Earth has been "flooded" before when it was hot and all the ice had melted. 

In doing a bit of research on the cover, I found an interesting web site titled, "Watts Up With That?". In a piece about the National Geographic article, Anthony Watts examines whether or not the dramatic image of a flooded Statue of Liberty, nearly up to her waist, was dramatic hyperbole or really at an elevation of 216 feet .

Image: Watts Up With That?
The results: The cover really shows the Statue of Liberty flooded up 216 feet from current sea level.

The article takes a human caused global warming skeptical point of view, but I appreciated the technical analysis in the article. A graph in the article (sourced from NOAA) shows that since 1850, sea level rise has gone up, on average, about 2.77 mm per year. To get to 216 feet, it would take 23,500+ years at that rate. Even a 3 times increase in the rise would take nearly 8,000 years. I calculated that the National Geographic super rough estimate would call for sea level rise to increase 4.7 times its current rate.

It should be noted that sea level has been high in the past and at times risen dramatically in the past. Sea level in the Bay Area was 30m higher, or 98 feet 125,000 years ago.
Source: San Andreas Fault and Coastal Geology, from Half Moon Bay to Fort Funston-Crustal Motion, Climate Change, and Human Activity by Andersen D., Sarna-Wojcicki, A., Sedlock, R. (2001).
Image: K.R. Lajoie via Changing Landscapes by Lisa White

According to a report by the University of Colorado, and mentioned in Watts Up With That sea level rose about 14mm/year – which is more than four times faster than the current rise, 15,000 years ago to 8,000 years ago. 

So even if our climate system hits the fan, it will take several thousand years before Chowchilla or Fresno become shoreline cities (or dead cities).

Finally, let's see if changing 200' to 225 sea level rise does much to San Francisco's Archipelago. I wish I could do 216 feet, but I only have elevations broken out every 25 feet. It probably won't be dramatically different (from a map perspective).

San Francisco with 225 foot sea level rise. Image: Urban Life Signs
A few island are split up. Telegraph Island, and Bernal Isle become two islands. Alamo Square becomes Alamo Island, and the Funston Islands/Peninsula becomes a lot smaller.

Although we're talking about a hot planet, with maximum sea level rise (sorry Waterworld), let's not forget Snowball Earth. That's when the entire planet, or very nearly, was covered in ice.

Image: CosmosMagazine.com


Popular Posts