# Sea level rise predictions?



## BetaWolf (Apr 22, 2013)

Another science question: What prediction of sea level rise is plausible in the next half century? Century? I'm working on a story set in the southern USA (Florida mostly) in the late 21st century and wanted to know what was plausible if global temperature increases continued.

Here's a nice tool to play with: http://geology.com/sea-level-rise/


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## BetaWolf (Apr 23, 2013)

Of course, things could go the other way--a new ice age.


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## Venusian Broon (Apr 23, 2013)

Off the top of my head, I remember reading an article that suggested that in the next 100 years (or was it 200???) that *at most *it would be about 2-3 metres. I'm not being precise, am I 

However that I think was from scientfic knowledge a couple of years old - this is a very fast moving field. I think recently they published a finding that they got the thermal expansion of the oceans due to heating wrong - it's bigger than they expected. 

The other thing to remember is that I think this assumes that both Greenland and (definitely) Antartica hold on to most of their ice. Antartica is probably a cert to do this - as global warming is likely to increase precepitation in the area and add more ice/snow. If in your story the Antaratic was to partially melt (Somehow ) that could add anything up to 40-80 metres...

The other thing to think about is the land - I just last night was reading up on river deltas and the fact that they are all sinking. Mainly because human activity is stopping sediment coming in and creating fresh land, but other activities such as extracting ground water and gas is causing coastal land to sink and compact. In some river deltas I believe it is about 1.5cm a year - which is a lot. 

Anyhow, take everything I've written above with a pinch of salt, it's all from memory - I can try and dig out the articles if your interested (hope I still have them!)


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## Vertigo (Apr 23, 2013)

I think in the current climate of skepticism and conflicting theories you are in a bit of a no-win on this one; if you set your story with major sea level rises some will accuse you of being alarmist and if you set it with minor rises others will accuse you of sticking your head in the sand.

Personally, applying my own filters to all the reports I hear, I suspect we will lose at least some of Greenland's and Antartica's ice caps but not all and that rises in the order of 5-10 metres are reasonably likely in the next 100 years. Which is more than anough to be catastrophic in some parts of the world.


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## Stephen Palmer (Apr 23, 2013)

I think the average likely rise this century is about a metre - it could be more, or less. Sea level rise is not a quick phenomenon however. The question really is what will it be like in 2999...


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## BetaWolf (Apr 23, 2013)

Thanks for the info, guys. I am going to be rather conservative with my sea level rise estimates, but I've considered the strategic possibilities of messing with sea levels during an interplanetary war. Lasers or a great deal of heat directed towards Greenland, in other words. I'd rather have a significant but rather moderate increase in sea levels--say five meters--in this story. I'm not writing the prequel to Waterworld here.

@Vertigo: That's what I was thinking of. The story is set in a much reduced Florida, which the US Geological Survey predicts to look this way with a 5m rise: http://www.teachingboxes.org/seaLevel/lessons/lesson4_reefs/florida_shore_5m.htm

@VB: I've run across info like that on Antarctica as well. The global feedback loops are still not properly understood, but AFAIK Antarctica will indeed get more precipitation, thereby cooling the planet (or helping offset global warming) over the long term. The North Atlantic currents that help regulate global heating and cooling seem to be sensitive to how much ice there is at the north pole.

@Stephen Palmer: That's quite the issue. Both winter storms and summer hurricanes will likely get worse rather than better, so even small increases will likely cause coastal protective measures to fail progressively. I don't trust national and regional leaders to think much beyond the next election, however.


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## Abernovo (Apr 23, 2013)

One thing you might want to look at (although you've probably already thought of it) is not just the land covered by seawater, but the total land affected. Increased storms will lead to more flooding, salt contamination, waterlogging, etc. to areas above the new coastline. There's also increased risk to homes, businesses, and utilities. Some areas might be abandoned as too high an insurance risk, leaving the people there in limbo.

Sorry, not your exact question, but I tend to think of the impacts. The actual increase is hard to predict precisely, not least because there's so many variables. As you've said, you're damned if you do, damned if you don't.

Some river ecology would likely change, as the higher sea levels push into the valleys and gulleys, altering the point where fresh and salt water met. There's also the possibility of storm surges rolling over higher ground to collect, and become trapped, in any low-lying areas behind. Happiness and light, am I not?


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## BetaWolf (Apr 23, 2013)

Thanks, abernovo. Those are some bigger ramifications than I had considered thus far, actually. So more food for thought.  My story is pretty localized in the southeastern corner of the USA and the nearby West Indian islands (the geography I know best). Pair up quick sea level rise and an epidemic caused by a space-borne pathogen and things go to hell pretty quickly. My MC and her family has to weather it the best they can. More apocalyptic family fun.


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## Venusian Broon (Apr 23, 2013)

Abernovo said:


> There's also the possibility of storm surges rolling over higher ground to collect, and become trapped, in any low-lying areas behind. Happiness and light, am I not?


 
Yep, Storm surges can be utterly devastating if it hits the wrong spot - we all know of the Hurricane's Sandy and Katrina, probably about 200 billion dollars of damage between the two and unfortunately close to 2,000 deaths, but compare that with Cyclone Nargis that hit Thailand in 2008 - a minimum of ~140,000 deaths - appalling. 

Of course being wealthier the US should be better prepared with its storm protection - but I think that's the issue with rising sea levels (especially fast ones), it helps big storms to bypass the old sea defences before we can put new ones up and impact areas that before you wouldn't have expected to see the sea.


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