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>mostly in poor countries Ice shelf melting will be devastating to coastal areas worldwide if it happens quickly. How many cities along the coasts of the world

>mostly in poor countries Ice shelf melting will be devastating to coastal areas worldwide if it happens quickly. How many cities along the coasts of the world's oceans are above 20' in altitude? Or above 200'? [1] A 20' rise is likely, possibly in "decades", and 200' is the rough estimate if we lost both the Greenland ice shelf and Antarctica's -- and every time a new report comes out it seems like things are happening faster than scientists were predicting. I've seen this movie, and it doesn't end well. And 20' is enough to put New York City underwater. Are they just going to build a 30' dike around the entire area? What if the oceans start really rising toward 200'? Build another 30' onto the dike every decade? If things happen slowly enough, sure, you could evacuate New York City, and the people there wouldn't number among the casualties, but where would you move them? Or the rest of the Atlantic coastal cities? Or the people in the Los Angeles basin? Some areas may be easier to protect from rising oceans, but there are probably 100 million people in the US alone living in areas that would lose homes to flooding with just a 20' sea level rise. Twice that and you probably get half the population, since most of the biggest metro areas are coastal. Worldwide? We're probably looking at billions of deaths from a 20' rise in sea level, not even counting other negative effects. [1] https://thinkprogress.org/study-were-already-in-the-worst-case-scenario-for-sea-level-rise-a62883b6bc84 https://thinkprogress.org/study-were-already-in-the-worst-ca...

0xffff2 10y ago
Billions of deaths? Really? No matter what happens, we aren't going to see several feet of sea level change in a matter of hours, which is what it would take to cause large scale casualties. To be sure, the economic impact of sea level rise is potentially devastating, but billions of deaths is wildly hyperbolic.
- SomeCallMeTim 10y ago
  >in a matter of hours First, it doesn't need to be "hours" to ultimately kill millions in the US and billions worldwide. Say it happens over a month. Where are those billions going to go? Think Katrina in slow motion, only with 100M+ people's homes under water in the US and ~3 billion people worldwide homeless, so pretty much no country anywhere is going to be able to send meaningful aid to anyone. The people won't drown, no. But where will they get food? Housing? Clean water? At ~20', almost all coastal airports be submerged (they tend to be close to 0'). Much of the coastal transportation network will be submerged. Ports will (nearly) all be useless; container ships won't be able to deliver goods to the US because the infrastructure will need to be rebuilt. What if it happens in our winter (summer in Antarctica!)? How many on the East Coast will freeze just because the disaster response brought people tents and there aren't enough sleeping bags for 40M people? Ice sheets sit on liquid water. The pressure is too great underneath a mile of ice for water to remain frozen. An earthquake a stress fracture that develops over time could easily get to the point where a large chunk of the shelf breaks off, and if it's big enough, the water will rise. 200 feet of potential sea level rise is bottled up in those ice sheets. "Several feet" could be in the small number of percentage points of that potential. And it could also have a cascading effect, where the higher sea level causes the remaining ice to calve more quickly. In fact the USGS called out at least one such scenario: "The West Antarctic ice sheet is especially vulnerable, because much of it is grounded below sea level. Small changes in global sea level or a rise in ocean temperatures could cause a breakup of the two buttressing ice shelves (Ronne/Filchner and Ross). The resulting surge of the West Antarctic ice sheet would lead to a rapid rise in global sea level. " [1] They don't define "rapid", and I don't expect they mean hours, but it could be over weeks. They're geologists, so they might mean years. I don't know. The Larsen-B ice shelf broke apart completely in just weeks, though [2]. Even if it happened over several weeks, it's hard to imagine any kind of response that doesn't involve a huge chunk of the population dead or dying over the course of the next few months and years. Dismissing the result and claiming it can't happen feels like intentionally burying your head in the sand. [1] http://pubs.usgs.gov/fs/fs2-00/ http://pubs.usgs.gov/fs/fs2-00/ [2] http://www.slate.com/blogs/the_slatest/2015/05/15/antarctica_sea_level_rise_nasa_study_says_larsen_b_ice_shelf_collapse_is.html http://www.slate.com/blogs/the_slatest/2015/05/15/antarctica...

0xffff2 10y ago

Billions of deaths? Really? No matter what happens, we aren't going to see several feet of sea level change in a matter of hours, which is what it would take to cause large scale casualties. To be sure, the economic impact of sea level rise is potentially devastating, but billions of deaths is wildly hyperbolic.

SomeCallMeTim 10y ago
>in a matter of hours First, it doesn't need to be "hours" to ultimately kill millions in the US and billions worldwide. Say it happens over a month. Where are those billions going to go? Think Katrina in slow motion, only with 100M+ people's homes under water in the US and ~3 billion people worldwide homeless, so pretty much no country anywhere is going to be able to send meaningful aid to anyone. The people won't drown, no. But where will they get food? Housing? Clean water? At ~20', almost all coastal airports be submerged (they tend to be close to 0'). Much of the coastal transportation network will be submerged. Ports will (nearly) all be useless; container ships won't be able to deliver goods to the US because the infrastructure will need to be rebuilt. What if it happens in our winter (summer in Antarctica!)? How many on the East Coast will freeze just because the disaster response brought people tents and there aren't enough sleeping bags for 40M people? Ice sheets sit on liquid water. The pressure is too great underneath a mile of ice for water to remain frozen. An earthquake a stress fracture that develops over time could easily get to the point where a large chunk of the shelf breaks off, and if it's big enough, the water will rise. 200 feet of potential sea level rise is bottled up in those ice sheets. "Several feet" could be in the small number of percentage points of that potential. And it could also have a cascading effect, where the higher sea level causes the remaining ice to calve more quickly. In fact the USGS called out at least one such scenario: "The West Antarctic ice sheet is especially vulnerable, because much of it is grounded below sea level. Small changes in global sea level or a rise in ocean temperatures could cause a breakup of the two buttressing ice shelves (Ronne/Filchner and Ross). The resulting surge of the West Antarctic ice sheet would lead to a rapid rise in global sea level. " [1] They don't define "rapid", and I don't expect they mean hours, but it could be over weeks. They're geologists, so they might mean years. I don't know. The Larsen-B ice shelf broke apart completely in just weeks, though [2]. Even if it happened over several weeks, it's hard to imagine any kind of response that doesn't involve a huge chunk of the population dead or dying over the course of the next few months and years. Dismissing the result and claiming it can't happen feels like intentionally burying your head in the sand. [1] http://pubs.usgs.gov/fs/fs2-00/ http://pubs.usgs.gov/fs/fs2-00/ [2] http://www.slate.com/blogs/the_slatest/2015/05/15/antarctica_sea_level_rise_nasa_study_says_larsen_b_ice_shelf_collapse_is.html http://www.slate.com/blogs/the_slatest/2015/05/15/antarctica...