[saalweachter]

I mean, if you waved a magic wand and CO2 levels were back at 280ppm? Maybe you'd expect sea levels to stabilize at their current levels?

There's at least four pieces of inertia here that make preventing sea-level rise hard absent such a magic wand:

1. We're not at equilibrium temperature for our current CO2 levels; if you stopped generating CO2 at an industrial scale and we kept the atmosphere to 420ppm CO2, you'd still expect to see the mean global temperature rise.

2. Even absent increases in CO2, the ice that continues to melt until the new equilibrium is reached decreases the reflectivity of the Earth.

3. The ice that's already melted has decreased the weight on the continental places upon which it rested; the plates are still rebounding, and it can be easier for ice to fall off as they raise.

4. Once we reverse course and ice is no longer melting, it will take a long time for the ice to re-form and the water to be removed from the oceans, lowering sea-levels (and storm surges). Some of the places the ice is disappearing from is effectively a desert, with very low rates of precipitation.

[pier25]

> We're not at equilibrium temperature for our current CO2 levels; if you stopped generating CO2 at an industrial scale and we kept the atmosphere to 420ppm CO2, you'd still expect to see the mean global temperature rise

Exactly.

We're really in uncharted territory. The IPCC et al can show the results of models etc but nobody really knows how bad things are going to get, even if a miracle happened and we reached zero emissions today.

Last time the Earth was above 400ppm of CO2 was during the Pliocene Epoch (2-5 million years ago). Temps were 2-3ºC higher and sea level was about 30 feet higher. We're now at about 420ppm and rising.

[tuatoru]

5. The ocean has warmed, and it would take time to cool down again. That will continue to affect Greenland for a century or more.

[saalweachter]

Oh yeah, a goodly portion of the sea level rise is thermal expansion, isn't it?