If all the ice in Antarctica were to melt, how much would global sea ...

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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 tricky 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].
I am a Senior Lecturer at Newcastle Univeristy, specialising in glaciology and glacial geology. I wrote and developed the AntarcticGlaciers.org website as part of an ongoing commitment to outreach, education and research impact. Read more about me at www.antarcticglaciers.org/bethan-davies.
75 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.
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
Anonymous said
“get a glass, put in a couple of ice blocks, then fill the glass to the brim with water. Then leave the ice to melt. The water will not overflow”
Your analogy here is INVALID & does not hold true for the real world example in question here. Let me explain:
This means icebergs and sea ice, after melting to liquid will occupy between 1% & 2.5% MORE volume than when frozen.
Your analogy was an example of
‘Archimedes Principle’ and only holds true when bodies of the SAME DENSITY are considered. The real world of density differentials between icebergs, pack-ice and seawater is a far more complex and nuanced environment than your glass of water.
You could try to replicate the experiment using frozen freshwater ice cubes in a known volume of water but on such a small scale you’ll need EXTREMELY accurate means measure volume, densities and to account for water tension which will have an appreciable impact on such a small scale representation.
One final point if I could ….. I applaud ppl with traits of open-mindedness, curiosity & humility …. traits that compel them to ask questions & learn.
Calling people “Idiots” demonstrates zero humility or curiosity, nor is it openminded.
I hope you manage to get past this stage. The toxic landscape of ‘contempt prior to investigation’ leads nowhere good my friend., I mean that with much sincerity.
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.
Haris – We DON’T need to fight climate change, at least not because the sea level is going to rise 1 or 2 inches in 80 years! We do have other more pressing environmental concerns, such as the massive deforestation in Africa, wind turbines killing our large migratory birds, bats and insects! We need to be spending our money wisely not on a fool’s errand trying to change something we have no chance of changing. Protecting our environment should be our priority. Mining for rare-earth minerals and Cobalt, so we can produce an unbelievable amount of batteries that will need to be replaced and recycled every 5 – 10 years is environmentally hostile and definitely NOT renewable energy. We can, (and will very soon), get 100% carbon capture on oil and gas production without poisoning our environment with real toxins from mountains of batteries. Most of these batteries will NOT be recycled properly in most areas of the world, (China, India, South America, Africa, Middle East), because they just don’t have the economy to do so. (Proper, environmentally sound, recycling of batteries is a lot more expensive than producing them.)
Considering AGW was a scam and we are now in a cooling phase because of teh solar minimum, this is all futile, there is mo such thing as a greenhouse gas outside a sealed lab flask because of convection.
Eating less meat won’t help with climate change. I mean, really explain to me how eating meat harms the environment. I understand climate change is real, and alot of things are being done to try and slow the process down. However, no scientific evidence exists that proves cutting out meat from our diets would help.
AverageJon – Just to make sure you understand the above article. The beginning of Paragraph 2: “Global sea levels are predicted to rise by 20-60 mm by 2100″
In case you misunderstood something: 20-60 mm is 0.78″ – 2.36”.
So NO, a lot of people will NOT be flooded out during our lifetime! We DON’T need to figure out what to do about it.
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
If you do the calculations using the total volume of ice above sea level at 30 million cubic kilometers, you end up with a rise of approx 15 meters.
I have seen and heard figures of 70m, which needs about 1500 million cubic kilometers of ice.
So I always take sea level rise with a grain of salt. Best example I can find is Port Denision in Sydney Harbour, Photos from the early 1900’s show the sea level at a very similar point to what can be seen today.
Also, as the water would flow into the oceans, I would assume they would depress the crust down with the extra weight moving to the center and force other higher areas to rise?
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
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.
Hmm, using the volume on a sphere and the average diameter of earth as 12742000 meters, 26.5 cubic kilometers will only increase the sea level by a little under 13 meters, and even taking all the land mass the already occupies the area above sea level, shouldn’t get much higher than 16 meters total.
Yes there will be a sea level rise, but it’s not going to be nowhere as high as some people say. Trying to work it out using area is prone to errors, where as using the volumes of a spheres and some simple subtration, tou can find the total volume of a shell at x meters high.
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.
All the calculations I have found use the total amount of ice in the ice sheets, not just the amount of ice above sea level. I have not seen one calculation that uses the decreased volume of water to ice. I have done the calculations as if all the ice were above sea level without allowing for the difference in volume and I get the same number of sea level rise. But we know that most of the ice sheets are not on land, but in the water. So, has anyone calculated the real amount of rise? Back in 1999 I was able to find the amount of ice above sea level and calculated that displacement was not near the amount now reported, but now the amount of ice above sea level is top secret, I can only find total ice in the ice sheets. Can you direct me to where I can find how much ice is above sea level so I can do the math?
Except the world is cooling and both poles are gaining ice, its called a solar minimum and was predicted since at least the 1990s when we last had warming! Most of the recorded warming is fake adjusments for grant money or UHe because of poorly sited stevenson screens. CO2 has no warming ability outside a sealed lab flask so outside normal oscillations the ice won’t melt! remember when the Vikings colonised Greenland half the ice was not there !
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.
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?
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?
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.
I am not a scientist; but I am very worried about the faster and faster ice melts in the Arctic and Antarctic. The ice melts faster, because it leaves more adjacent land to absorb more heat; the ice reflects the heat and stays colder. I read in Popular Mechanics “NASA Found a Giant Underground Cavern in Antarctica Almost the Size of Manhattan, by Avery Thompson, January 31, 2019″…”In Thwaites’ case, that radar uncovered a gigantic canvern between the glacier itself and the bedrock below it. That cavern is likely filled with air much warmer than the surrounding ice, triggering faster melting of the glacier than would happen otherwise. Thanks to this nearly Manhattan-size gap in the ice, the entire glacier along with the surrounding ice sheet will likely disappear much more quickly. So what happens if Thwaites melts? Immediately, we’d get 2 feet of sea level rise. But the real danger is what happens after. Thwaites holds back a large portion of the West Antarctic Ice Sheet and a handful of nearby glaciers; if Thwaites disappears, we could see an additional eight feet of sea level rise from these sources, on top of the two feet from Thwaites itself. [THIS IS A 10 FOOT RISE IN OCEAN LEVEL FROM THE SIZE OF MANHATTAN. MANHATTAN IS 22.82 SQUARE MILES. I READ A FEW YEAR AGO THAT AN AREA OF ICE THE SIZE OF CALIFORNIA BROKE OFF OF GREENLAND. CALIFORNIA IS 163,696 SQUARE MILES, OR 7,173.35 TIMES AS LARGE AS MANHATTAN X 10 (1 FOOT RISE FROM MANHATTAN SIZE) = 71,734 FEET RISE IN THE OCEAN!? AGAIN, I AM NOT A SCIENTIST OR MATHEMATICIAN.] Even more worrying to scientists beyond the cavern’s existing is how quickly it appeared. The cavern first appeared in 2012 and most of the ice that once occupied it melted in the last three years. Most models of the Thwaites glacier don’t take into account rapid cavern forming, so the entire glacier is likely to be melting much faster than our predictions estimate. In other words, there’s a good chance we could be looking at some serious melting in the near future, thanks to this glacier and the ice around it. Source: NASA.”
Dont fret its all a scam! there was little ice on Greenland when teh Vikings colonised it and vines grew in teh Canadian seaboard! it was way warmer then and no evidence sea levels were higher! NASA will tell you the world is now cooling!
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.
Read the same news today, and some of the study that was published on nature on the subject. It also seems that the smaller the weight of ice is the more active they could become and could cause much faster ice melting that predicted this far. A 50-meter fast sea level rise would catastrophic
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.
I am not a scientist; but I am very worried about the faster and faster ice melts in the Arctic and Antarctic. The ice melts faster, because it leaves more adjacent land to absorb more heat; the ice reflects the heat and stays colder. I read in Popular Mechanics “NASA Found a Giant Underground Cavern in Antarctica Almost the Size of Manhattan, by Avery Thompson, January 31, 2019″…”In Thwaites’ case, that radar uncovered a gigantic canvern between the glacier itself and the bedrock below it. That cavern is likely filled with air much warmer than the surrounding ice, triggering faster melting of the glacier than would happen otherwise. Thanks to this nearly Manhattan-size gap in the ice, the entire glacier along with the surrounding ice sheet will likely disappear much more quickly. So what happens if Thwaites melts? Immediately, we’d get 2 feet of sea level rise. But the real danger is what happens after. Thwaites holds back a large portion of the West Antarctic Ice Sheet and a handful of nearby glaciers; if Thwaites disappears, we could see an additional eight feet of sea level rise from these sources, on top of the two feet from Thwaites itself. [THIS IS A 10 FOOT RISE IN OCEAN LEVEL FROM THE SIZE OF MANHATTAN. MANHATTAN IS 22.82 SQUARE MILES. I READ A FEW YEAR AGO THAT AN AREA OF ICE THE SIZE OF CALIFORNIA BROKE OFF OF GREENLAND. CALIFORNIA IS 163,696 SQUARE MILES, OR 7,173.35 TIMES AS LARGE AS MANHATTAN X 10 (10 FOOT RISE FROM MANHATTAN SIZE) = 71,734 FEET RISE IN THE OCEAN!? AGAIN, I AM NOT A SCIENTIST OR MATHEMATICIAN.] Even more worrying to scientists beyond the cavern’s existing is how quickly it appeared. The cavern first appeared in 2012 and most of the ice that once occupied it melted in the last three years. Most models of the Thwaites glacier don’t take into account rapid cavern forming, so the entire glacier is likely to be melting much faster than our predictions estimate. In other words, there’s a good chance we could be looking at some serious melting in the near future, thanks to this glacier and the ice around it. Source: NASA.”
“That cavern is likely filled with air much warmer than the surrounding ice, triggering faster melting of the glacier than would happen otherwise.”
Do you understand the laws of thermodynamics? How does the air get warmer than the ice? Where is the heat source? When the ice melts, the air will get colder until equilibrium is reached and then no heat transfer, and no melting. For the ice to melt, the air must get colder or their must be a heat source. Is there a volcano under the ice? If so, there’s not much humans can do about it.
The area of Antarctica is about 5.4 million sq. mi. (not including the ice shelf because it will not affect the water level)
The area of the ocean is 361.1 million sq. mi.
We have 361.1/5.4 = ~67 times as much ocean area as the area of Antarctica.
The ice covering Antarctica has an average thickness of about 1 mile (5280 ft.)
But 45% of that ice is below sea level, so only 55% of it will affect the elevation of the ocean, i.e. the equivalent of 5280 x 55% = 2904 ft.
If we dropped that large chunk of ice into a body of water the area of Antarctica the water would rise only 90% of the 2904 ft. because it loses 10% of its volume when it melts, it would actually rise 90% of 2904 ft. = 2614 ft.
Since there is 67 times as much ocean area as the area of Antarctica, if you spread that water (the melted ice) over the whole ocean area it would rise 2614/67=39 ft. Since this increased level of the ocean would cause the water to creep up on all the coasts and up rivers and raise the levels of many lakes, it would be further reduced. I don’t have data to do an accurate calculation but let’s estimate we might lose 15% of land area on the globe.
That leaves us with an ocean level rise of 39 – 15% = 33 ft. But since the depth of the water varies significantly on this newly flooded land, let’s estimate the average depth to be about half of the 33 ft. That would leave us an adjusted level of about 36 ft.
That is a fraction of the figures I see thrown around, and although still alarming for distant future generations, much less so, actually of very little consequence to me and my present offspring.
What am I missing in my calculations or in my science?
I am not a scientist.
I have never honestly thought about what would happen if the ice caps melted. But Ever since I was nine years old, twice a month, I would have an alarming dream about the ice caps melting, the ocean rising, and all or nearly all land dwelling creatures, would as a result be sucked into ocean by riptide currents. Resulting in a majority loss of land dwelling creatures on the Earth.
Some of the water would get absorbed by the volcanoes underneath the antarctica, either in evaporation or phsically pour into them and act as drainage, which would lessen the effect of oceanic expansion onto our dry land
There is a vast volume of ice in Antarctica. The volcanoes (or areas with high geothermal heat flux) under the ice are already in contact with water because they melt the ice above. So this would not make a difference.