What is a realistic sea level rise projection for the next 20 years?

[mahina]

There are a zillion websites out there but I trust you guys already, so have to ask. Links and citations much appreciated.
Our family has to consider whose home will be under water.
Thanks!

[HereSince1628]

1. Somewhere between 37 mm and 3 meters

Take you pick. The model assumptions control the outcome.

[Kutjara]

2. I don't think the mathematical models are...

...sufficiently robust yet to call any of them "realistic." While they all (well, all the ones not funded by Exxon, that is) show unequivocally that sea levels will rise, the number of variables is simply too large to predict actual outcomes with any accuracy. Even if there was broad agreement on all the variables that must be included, very tiny differences in the starting values of those variables can produce wildly divergent outcomes.

The big message about climate change that often gets lost in the "it will be x degrees" hotter debates is that not only will the Earth (on average) be warmer, but that the climate will be pushed away from equilibrium. This will tend to make weather patterns, temperature distributions, rainfall levels and any other climate metric you care to consider chaotic and, hence, unpredictable.

[whistle]

3. 2" to 2 1/4"

<snip>
Sea-level rise is an increase in sea level. Multiple complex factors may influence this change.

Sea-level has risen about 130 meters (400 ft) since the peak of the last ice age about 18,000 years ago. Most of the rise occurred before 6,000 years ago. From 3,000 years ago to the start of the 19th century sea level was almost constant, rising at 0.1 to 0.2 mm/yr.<1> Since 1900 the level has risen at 1 to 2 mm/yr; since 1993 satellite altimetry from TOPEX/Poseidon indicates a rate of rise of 3.1 ± 0.7 mm yr–1 <2>. Church and White (2006) found a sea-level rise from January 1870 to December 2004 of 195 mm, a 20th century rate of sea-level rise of 1.7 ± 0.3 mm per yr and a significant acceleration of sea-level rise of 0.013 ± 0.006 mm per year. If this acceleration remains constant, then the 1990 to 2100 rise would range from 280 to 340 mm,<3>. Sea-level rise can be a product of global warming through two main processes: thermal expansion of sea water and widespread melting of land ice.<4> Global warming is predicted to cause significant rises in sea level over the course of the twenty-first century.

http://en.wikipedia.org/wiki/Sea_level_rise

[phantom power]

4. A couple inches is reasonable, extrapolating current behavior...

which is slow acceleration.

I can imagine "plausible" unexpected events, like a sudden huge melt-rate increase in Greenland. But that kind of event is unpredictable, and not much sense trying to predict it.

As any fan of space travel knows, even slow acceleration adds up faster than you think.

Quadraticly. It grows quadratically.

[Speck Tater]

5. The wild card is Greenland.

If one of those big ice sheets slides off the continent and into the ocean, we could have not only a HUGE tsunami, but a foot or two rise overnight.

Of course, that's not very likely, but then, it's not impossible either.

[mahina]

13. When a climate conference came here recently,

a group of students lead by the Sierra club chalked a blue line at the 1' rise level. If sea level rises, Waikiki, all of it, is under water.
Lousy!

[Broadslidin]

6. Well let's see, the single highest point above sea level in Florida is 54 feet....

Sorry,
That little known knoll has already been snapped up by speculators.

[mahina]

14. Thanks, but I'd rather stay home in the islands if possible.

I bet we'd still have to pay our mortgages even in the homes were under water.

[kristopher]

7. What is it you really want to know?

The first point to highlight is that 20 years is very near term and, based on probabilities, little increase is expected in that period.
Second, is that the volume of the ocean has increased (thermal expansion) over the past century enough that we are already seeing an effect on storm driven tides. Some coastal areas that have historically weathered bad storms are now affected. Over the next 20 years, that can be expected to continue to surprise people who who thought they lived outside the danger zone of coastal flooding.

You might find this informative. http://www.eoearth.org/article/Sea-level_rise_and_coastal_stability_in_the_Arctic

It gives a good rundown of the subject, even though it focuses on the Arctic.

[mahina]

12. Mahalo for your response.

I want to know if my home, and my families homes, are going to be submerged in the next 20 years.
Thanks~

[kestrel91316]

8. My opinion, based on, well, my opinion, is 5 feet.

But then I have turned into a doom-and-gloom sort over the years.

[Dover]

9. Potential for "Abrupt Change" is the most current scenario based on the latest reports.

I agree with the poster who said each area will be unique based on any number of variables so they have not yet been able to map the rise with any area-specific detail. I know someone who is working on this evaluation and mapping on the east coast and he feels as though the process is way too slow in response to the potential for 'abrupt change'. So you may not get the answers you are looking for anytime soon. There are some new maps available however which you can look at. I just read an article that said France/US has launched a satellite specifically to measure and map sea rise and current changes >>
http://www.oceanconserve.org/shared/reader/welcome.aspx?linkid=101713

Personally, I think the coastline is a pretty risky place at this time with the increasing size and destructive ability of storms as well as sea rise. But you have to go with your own gut on this.

These are two threads on this topic I posted in the Science Forum:


http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=228&topic_id=39523&mesg_id=39523


Newest Report:
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=228x40006

[mahina]

11. Thank you,

my whole family lives on Oahu. I appreciate your links and info, aloha.

[Dead_Parrot]

10. 2-3 inches is my guess

But if you're considering moving, I'd rule out anywhere under 10 feet - not because it'll be flooded out anytime soon, but once people finally twig what's going on the value of low-lying coastal properties will nose-dive. I'm no property guru, so you might want a second opinion on that. :)

[mahina]

15. Pretty sure you're right.

It escapes me how anyone can build on sand in the first place and feel comfortable. But then I live on a bump in the middle of the ocean. People could drive from Louisianna when Katrina was imminent- we'd be stuck.

Twig? One more new word please!