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.

32 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!!!!!!

      • NO….. I was told the maximum would be around 236 ft well any land that is over 260 ft in elevation would remain.the coastline will change world wide due to the raising of water.. Miami NYC all gone. burt new beaches and new rivers and lakes

    • 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.

      • we NEED to fight climate change each one of us individually. Mostly, USA and China. Recycle, make economy, use less plastic, eat less meat, buy eco-friendly products (switch to veganism). Simple, but not a lot of people seem to understand it. Good luck dear world.

      • There’s a crack in one of the biggest shelves rigiht now that they say is getting ready to drop the biggest iceberg in recorded history… And once that breaks away those glaciers are going to be running freely and this could weaken the remaining shelves…. Breaking news

  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

    • I agree… You can’t stop mother nature… It comes down to how fast will the glaciers flow without the ice shelves to slow them… My guess is pretty dang fast…

    • there is every sort of disinformation on the result of ice meriting. A fellow told me that if just the ice on Antarctica melted the seas would rise 174 ft. That sounded more that a little excessive so I did some calculating:
      the area of earth is 196,900,000 square miles
      2/3 is the ocean so, 131,923,000 Sq Mi
      1 sq mi of 174 ft of water is 5280 X 5280 X 174 cu ft
      that’s 4,850.841,600 cu ft per sq mi 174 ft deep times the sq mi of ocean.
      639,937,576,396,800,000,000 hang on, we go smaller from here. So 1 cubic mile of water is 5280 X 5280 X 5280
      that is 147,187,952,000 cu ft which we divide into total cu ft, or 4,347,462,500 cu miles of water to raise the seas 174 ft.
      Antarctica has 5,405,000 square miles so the ice would have to be 804 miles high. I don’t have to tell you it isn’t, It is 1.3 mi, we have to divide the real height. into the theoretical height to find the real amount of rise if the ice melted.the answer is 619, into 174, or .28 ft (3.4 inches). of course if Antarctica melted so would Greenland and all land based year round ice, however Greenland is only 13% the size of Antarctica, but let’s be generous, lets say that all other year round ice is twice the amount on Antarctica. It still means that the seas would rise less that a ft. (10.2″) if all the ice meted. Relax, but move your beach towel a few yards up the dunes before 2100.

      • Your numbers are wrong. I do the same calculation, although I use meters as length units, and I arrive at numbers very consistent with the prediction of about 66 meters of sea level rise.

        The current Antarctic continent and ice cover about 14 million square kilometers, the planet’s oceans cover 361 million square kilometers. That’s a ratio of 25.78.

        According to Wikipedia, the estimated amount of ice in Antarctica is 26.5 million cubic kilometers. Dividing by the above two numbers, you get an average thickness of the ice cap of 1.89 kilometers and an average sea level rise of 73.4 meters.

        The last number is too high because the density of water is less than that of ice (multiply by 0.9 and you get 66 meters.

        The first number, 1.89 kilometers thickness of the ice cap is reasonable as the greatest measured thickness is more than 4 kilometers.

      • As someone has already posted, Antarctic ice melt won’t raise sea levels. The Antarctic Ice Sheet is floating on water, therefore it is already displacing its weight of water.
        Arctic ice is the threat, but of course climate change affects them both without distinction.

  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).

    • Where do you get the number 510 km2 from?
      In rough numbers, the circumference of the Earth is 40000 km (by the original definition of the meter!); that corresponds to a sphere with area 509 million square kilometers. But not all of the planet is Ocean! Google says it’s 361.1 square kilometers of Ocean. That is little more than two-thirds of the total surface.

  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?

  5. If Russia sends it nuclear ship that has a nuclear power stations on board to Antartica because that’s the way he sending it because it’s cheaper and it get stuck and they had a malfunction and it turned it self on to heat ! What damage could it do?

  6. It is untrue that the melting of icebergs will not raise the sea level. This would be true if the iceberg and the ocean water were the same density, but, they are not. The oceans are salty and the icecaps are fresh water, which is less dense. The result is that icebergs raise the sea level as they slide from the land into the ocean, and, icebergs raise sea levels again when they melt. You can see experimental proof at https://nsidc.org/news/newsroom/20050801_floatingice.html

    • Thanks for an interesting link. It does not help much to discard everything that we “alarmists” say as “alarmism.” Nobody serious is pretending that the Antarctic ice sheet will melt anytime soon. That ice sheet is thick; its top is at a very high elevation where the temperature is very low. The loss of mass will not happen primarily through melting but through ice flow. What the World is nervous about, is how much that ice flow will increase if the sea-borne sheets surrounding the continent break up and float away. Even as the precipitation is also expected to increase, the ice flow is expected to increase even more. The very article you link to hints at that — have you actually read it?

      In any case, the very question at the top of this webpage is quite hypothetical. It would take so long before all of the ice at the south pole melts, that our society would have changed completely over and over, and the current discussions about what we are to do with the emissions of carbon dioxide would have gone away thousands of years ago. We will probably have burned every smitten of coal, oil, and gas our planet contains long since.

  7. Just a thought. From what I’ve read, if any of the 138 Antartica volcanoes (especially of the 91 below the ice) see increased activity, then it would rapidly increase the melting of the ice sheets and raising of the sea level at a faster pace than anyone or models could predict.

  8. Floating ice that melts will result in no change to global sea levels. Only the ice on the East Antarctic shelf rests on the sea bed and so only ice above sea level in this region will contribute to a global sea level rise. Environmental “scientists” (deliberate quotation marks) are not too good at physics. Even if it were to all the ice were to melt, sea level would only rise 1-2 metres.

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