RE: A quiz15 Sep 2019 21:40
A couple of you have been doing your reading around and have come close with 65m, but I have to give it to Madasahat's 230 feet (70m) which is exactly the figure reported here :- https://www.amnh.org/explore/ology/earth/ask-a-scientist-about-our-environment/will-the-world-ever-be-all-under-water
Note that the ice only has to slide off of the landmass it is currently sitting on and fall into the ocean, at which point it will displace its mass of water and will float - the displaced water raises the overall ocean level even before the ice melts. Given the fact that the ocean occupies 2/3rds of the earth's surface it is fairly clear to see with a very simply model that even the most extreme flooding is not going to reduce the effect of the sea level rise by more than a factor of 1/3rd - at that point the earth would be entirely covered in water and we would not be around to argue about whether we should have factored in a small correction here or there.
The interesting question from that article is the statement :- " Earth is nearly as warm now as it was during the last interglacial period, about 125,000 years ago. At that time, sea level was 4 to 6 meters (13-20 feet) higher." - because the ice mass are so large, and the latent heat of melting of ice is so large, it take a long time for the ice system to come into equilibrium with the external environmental temperature - hence the sea level rise lags the global temperature rise.
Current human behaviour (not just CO2 and other greenhouse gases but also the greater generation of heat and change in the natural albedo, eg airplane trails) is changing the global temperature at a faster rate than has been measured before (last 800,000 years shown here:- https://earthobservatory.nasa.gov/features/GlobalWarming/page3.php - estimates that the current rate of warming is 10x that of any naturally induced warming) - hence we might conclude that once we reach equilbirum with just the warming we have now then the sea level would be around 5m higher.
Unfortunately the warming that we have now is the net result of all the CO2 and other gases that have already been pumped into the atmosphere, so unless CO2 and other emissions are stopped tomorrow AND ALL of the CO2 generated since 1850 is chemically removed from the atmosphere, then the warming is going to continue upwards before we have any chance to arrest it. Thus a 10m sea level rise does not seem unlikely, in fact it seem fairly conservative.
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