If all the ice in Antarctica were to melt, how much would global sea level rise? How quickly is this likely to happen?

Asked by Mike

This is a very difficult question to answer. The West Antarctic Ice Sheet has a global eustatic sea level contribution of 3.2 m[1] – that is, if all the ice in this area melted, global sea level would rise by 3.2 m. The Antarctic Peninsula Ice Sheet would contribute 0.24 m to global sea level rise on full melting[2], and currently contributes 0.22±0.16 mm per annum. The East Antarctic Ice Sheet has a sea level equivalent of approximately 60 m.

Global sea levels are predicted to rise by 20-60 mm by 2100, and possibly up to 1 metre. This is mostly from glacier melt and thermal expansion of the oceans. It does not include inputs from dynamic changes to ice sheet flow[3]. The West Antarctic Ice Sheet rests on ground below sea level (see Marine Ice Sheet Instability Hypothesis), which makes it potentially unstable[4]. It is possible that this could collapse rapidly and raise sea levels by 3.2 m, possibly within 500 years. Sea level increase of this rate and magnitude have been noted previously in the palaeo record[5]. The West Antarctic Ice Sheet has probably collapsed in the past, when temperatures were comparable with today’s or temperatures projected in the next few centuries[6].

1.            Bamber, J.L., Riva, R.E.M., Vermeersen, B.L.A., and Le Brocq, A.M., 2009. Reassessment of the potential sea-level rise from a collapse of the West Antarctic Ice Sheet. Science, 2009. 324(5929): p. 901-903.

2.            Pritchard, H.D. and Vaughan, D.G., 2007. Widespread acceleration of tidewater glaciers on the Antarctic Peninsula. Journal of Geophysical Research-Earth Surface, 2007. 112(F3): p. F03S29, 1-10.

3.            Willis, J.K. and Church, J.A., 2012. Regional sea level projection. Science, 2012. 336: p. 550-551.

4.            Ivins, E.R., 2009. Ice sheet stability and sea level. Science, 2009. 324: p. 888-889.

5.            Bentley, M.J., 2010. The Antarctic palaeo record and its role in improving predictions of future Antarctic Ice Sheet change. Journal of Quaternary Science, 2010. 25(1): p. 5-18.

6.            Joughin, I. and Alley, R.B., 2011. Stability of the West Antarctic ice sheet in a warming world. Nature Geosci, 2011. 4(8): p. 506-513.

9 thoughts on “If all the ice in Antarctica were to melt, how much would global sea level rise? How quickly is this likely to happen?

    • Dear William,
      Yes there will be some dry land – the mountains in the Antarctic Peninsula and the Transantarctic Mountains in West Antarctica will be left as islands. Much of East Antarctica would be above sea level even if all the ice melted.

      • that is not true if all the ice were to melt it would make something a glacier. this then removes rock so all the dry land would be taken away!!!!!!

    • William, it depends on where you live and how far above sea level it is. Scientists aren’t predicting that ALL the ice will melt for hundreds of years, so we probably won’t be around to see it.

      A lot of people will be flooded out during your life time. We need to figure out what to do about that.

  1. Thats a melt putting up to 200 ft of fresh water into the oceans which can change the flow of the oceans currents, possibly starting a new iceage.

  2. There are some errors in what people are being lead to believe. First ice takes more volume of space than water. Ice that is on water and melts will not be a problem as far as sea levels. The ice on land masses such as Greenland and Antarctica, however will cause the sea levels to rise. The speed at which this happens will make all the difference. Yes great volumes of fresh water dumping into sea water will change the salinity and that is a problem to life in the oceans. More water to evaporate will change weather patterns and increased humidity will make the air unbreathable at some point. Mass tonnage of glaciers on land masses will be relieved and the land elevation will rebound. We are still experiencing this effect in the northern states of the US with booms and cracks as the compressed land is still expanding therefore it will take a very long time to rebound and rise above the water levels. Lets break down the amount of rise. Let’s say both sheets melt, the West contributes 3.9 feet to the sea level and the East contributes 195 feet, that is less than 199ft in sea level rise. Okay what is the altitude of your city, state or country? Remember that rivers and streams will rise as well. We are at 718 feet above sea level – think we will be okay. The coast will definitely change and we may lose some states. Will there be enough space for everyone to live? Easily. We really don’t take up as much land as you might think because there are many unpopulated areas. You must understand as well that some of the warming and ice melt is out of our control and has nothing to do with surface issues. The current that travels from Antarctica north off the west coast of South America in the most recent years is being heated by increased activity of volcanic vents in the Pacific Ocean along the Ring of Fire and is much warmer when it reaches the Arctic than it should be and melts the ice from below, then as it makes the north warmer it returns to the south warmer than it should be as well contributing to the same effect. We have no control over what the earth does. The change in weather patterns is effected by the increased atmospheric moisture and the warming of the Pacific right now by the same vents. It changes the jet stream, increases precipitation and shifts where it is dumped and makes it less predictable and more violent cause there is more energy to feed into the storms. Global warming doesn’t mean we all get warmer and dryer, it means more evaporation and more atmospheric moisture which can mean colder and more snow as well. Season are then shorter, longer, unpredictable temperatures fluctuations, effecting growing seasons and large scale crop losses – which we can adapt to if we make changes on a massive scale to ensure crop production. We can make changes in how we effect the environment, but that will only delay the inevitable natural cycle, so if we are to survive we must start adapting now for those circumstances. We must prepare for the changes not just trying to stop them

  3. The area of all of the oceans is 510m km2. The total volume of all land based ice is 24m km3 therefore if all of the land based ice on earth melted sea levels would rise approximately47m (153ft).

  4. I think the amount of land will increase if the poles melt. Firstly it will take 100s if not 1000s of years for the ice to melt, by which time all the Skyscrapers of New York would have long been demolished and rebuilt (possibly further from the sea?). Secondly, the weight of sea water would compress the rock under the seabed creating deeper oceans and higher dry land, thirdly all of Antartica and Greenland would become available, and they’re huge! Dunno if anyone’s thought about that?

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