Arctic Replenishes Very Little Thick Ice

230 feet?

Are you sure you don't want to recalculate?

Why not 23,000 feet? I am sure that would get even more people to donate to the "global warming" organizations!

The problem with "global warming" is quite simply that there are way too many unsupportable claims being made about the consequences we face. One tasty little bit of info I heard recently was that the sun is getting hotter (about to supernova perhaps?) and we are going to be VERY warm in about 7,000,000 years.

Gee whiz folks! Let's get real and find out what is really going on before we tear apart the fabric of our existance!

Yes I am sure. If all the ice in the Antarctic ice sheet melts sea levels will rise by about 70 m or 230 feet. That's based on a volume of 30 million cubic kilometers of ice. There may actually be more ice than that so it could even be worse.

Regarding the Antarctic ice: there should be some compensation due to the globe reshaping as a result of the redistribution of the weight of the water, but I fear your number is broadly correct (my main uncertainty is how much of the Antarctic ice* is actually below sea level).
*included in the 30M cu km

Fyz

Interesting point Fyz. I seem to remember reading somewhere that Antarctica has the highest mean elevation of any of the continents, but I have been unable to confirm this. If that's the case then there would be very little ice below sea level. The Antarctic plateau has a mean elevation of nearly 10,000 feet and is a very inhospitable place, even bacteria have a hard time existing there.

I'm no expert, but my unreliable recollection is that some 10% of the area usually referred to as "land" in the Antarctic is actually below sea level - some of it several km below. In addition, quite a bit of the Antarctic ice is in regions described as ocean. However, the total volumes of ice usually given are sufficient to raise the oceans by significantly more than the 60-m quoted by Wikipedia - so I imagine that this is already a corrected figure. BTW, I believe the present rise in sea levels is more due to thermal expansion of water than ice contributions - indeed, the climate modeling I have seen suggests that increased snow-falls on Antarctica (due to its present low temperature, large thermal capacity, and the increase in the humidity of the incoming winds) will somewhat ameliorate the rises in oceanic levels for at least the next few years.

Fyz

Hi Fyz,

I have often wondered how much sea levels would rise due to thermal expansion. According to Wikipedia the world's oceans add up to something like 1,340 million cubic kilometers with average depth of 3,711 m.

The problem is the temperature and I havn't been able to find a figure for the mean temperature of the oceans. At any rate much of the ocean's volume is below 4° C and any warming of this water will negate a portion of the expansion of the water that is warmer than 4° C. It also depends greatly on the profile of the ocean floor and the shoreline that it expands into but if we assume that it is a vertical sided container with a depth of 3,711 m then the

• Volume = 1,340,000,000 km³
• Volume = 1,340,000,000,000,000,000 m³
• Volume = 1.34 x 10¹⁸ m³

Area of straight sided container

• Area = Volume ÷Depth
• Area = 1.34 x 10¹⁸ ÷ 3,711
• Area = 361 x 10¹²

So if we assume a worst case scenario of the temperature being 10° C the coefficient of thermal expansion is 8.8 x 10^-5 therefore increase for a 1° C rise in temperature is

• Volume_Increase = 1.34 x 10¹⁸ x 8.8 x 10^-5
• Volume_Increase = 1.179 x 10¹⁵

So if we assume a straight sided container then the rise in sea levels would be

• Depth_Increase = Volume_Increase ÷ Area
• Depth_Increase = 1.179 x 10¹⁵ ÷ 361 x 10¹²
• Depth_Increase = 3.266 m

Which is not an insignificant change but it is however the absolute worst case that I could think of. If you then include things like the area of land that is inundated and the fact that I believe the temperature is considerably cooler than the 10° C I have used then it will be substantially less. In fact it the majority of the ocean is below 4° C then there may actually be a net loss in volume as below 4° C water contracts as it expands.

After unsuccessfully trying to find out what the mean temperature of the worlds oceans I decided to produce the following chart. It shows how much the see level would change if the worlds oceans warmed by 1° C for a range of temperature from 0 to 30° C given the same conditions as above.

As you can see the range that the sea level can vary by is considerable and if the mean temperature is below about 4° C then there will be a drop. What w really need to do is find out the volume of the water at various temperatures. From this you could then calculate the relative expansion or contraction of the given volumes. To calculate the actual rise you then need to know how much land would be inundated with various rises in sea levels. At any rate the chart shows the absolute worst case so the actual rise will actually be less than this.

I think you might be using the figures for pure water at atmospheric pressures? I don't know this for certain, but I believe that the thermal expansion anomaly disappears under higher pressures; I also imagine that all the equivalent temperatures would be reduced with sea-water. The sorts of figures given for expansion to date are in the range of 1-metre.

Regarding the steepness of the edges - if you were to approximate the sea-bed as a shallow spherical bowl, the steepness of the edges would only halve the rate of rise. Given the dimensions of the oceans, the steepness of most of the sea-shores that I've seen corresponds to something much closer to a vertical wall. (However, once the immediate sea-shore is over-run, the steepness of the land reduces - and that would be when the real trouble begins)

Fyz

"I think you might be using the figures for pure water at atmospheric pressures?"

Yes I did use the figures for water at a sea level bit it was just to get some idea of the order of magnitude that is involved rather than an exact figure. If you have a link for the coefficient of expansion for sea water at various depths I will re do the calculation.

"Regarding the steepness of the edges - if you were to approximate the sea-bed as a shallow spherical bowl, the steepness of the edges would only halve the rate of rise."

I was thinking of something more like an inverted cone that had a median depth the same as the median depth of the ocean.

Sorry, I don't know where to find the data for salt water. (I Googled a few papers, but they are by subscription, and it's hard to deduce whether they would give the information we want).

Regarding fresh water, the best reference I could find is on Martin Chaplin's water site - the relevant part being at www.lsbu.ac.uk/water/explan2.html.
To summarise this: at the relevant temperatures, the thermal expansion of water increases with increasing pressure up to a pressure of about 400MPa. The reason for this is that the pressure inhibits the formation of the low-density state which can be formed at low temperatures.
My comment only: the low-density state can be regarded as a precursor for ice formation. As dissolved salt inhibits ice formation, I imagine that it too will inhibit this low density state. So I would expect surface sea-water to exhibit a positive expansion coefficient down to about freezing, and deeper water to be expansive down to -15 degrees

N.B.that a cone would give 1/3 of the rate of rise of a cylinder of the same area

Regards

Fyz

Hmmmmm.... so ALL of the water in the ocean expands? Does the water a couple miles down heat up as well?

I expect so - but I'm not certain when this would happen.

I'm possibly jumping to conclusions here - but I suspect that you expect that heating of water from 2-degrees will cause it to contract. I don't believe this to be true of of pressurised water.

(I doubt it applies to saline (sea) water at temperatures above 2 degC in the first place, as it has its entire phase structure shifted by downwards by about 2-degrees C, but I don't have access to any data on the subject).

I have however run some quick sums for fresh water [based on the compressibility vs temperature and the thermal expansion coefficient at normal pressures]. This strongly suggests that two miles down the pressure is more than sufficient to cause a positive coefficient-of-thermal-expansion at temperatures down to at least 0-degrees C.

Fyz

232.925 feet seems reasonable for 70 m. Rounded off to 230 feet also seems reasonable. Sun getting hotter is referencing sunspots wherein the sunspot area is cooler than the average sun surface temperature, but the surrounding surface is increased in temperature. Since we are approaching the end of an 11 year sunspot cycle within the next few years we can expect a gradual decrease in the amount of photon radiation reaching the earth from the sun with a subsequent reduction in overall atmospheric temperature as well as a decrease in ozone production with less energy to excite the oxygen molecule to the ozone level.

"Since we are approaching the end of an 11 year sunspot cycle within the next few years we can expect a gradual decrease in the amount of photon radiation reaching the earth from the sun with a subsequent reduction in overall atmospheric temperature as well as a decrease in ozone production with less energy to excite the oxygen molecule to the ozone level."

I think you will find we are about to enter what is called the solar max. The solar max is a period of increased activity on the sun that happens every 11 years and corresponds with the magnetic poles reversing.

There was recent a sun spot that had its magnetic field reversed when compared to all the other sun spots. This is usually the first sign that the solar max is beginning and that the process of magnet pole reversal has commenced.

In the news also is another 30-year warming trend. It seems that for as long as we've been recording it, the icecaps have been melting/receding, and temperatures have been rising alarmingly...on Mars.

It must be our little rovers. We must stop sending things to Mars, because we're warming that planet too.

Alternatively, we could decide that we actually want to warm Mars, and we can send all of our Democrats like Ted Kennedy and Al Gore (who belch twenty-times as much carbon and alcohol metabolites as the average citizen) there to help the process along.

Politics and hysteria aside, you have to admit that there is a hell of a lot of evidence that indicates that the Earth is warming.

The precise causes and ultimate effects are open to debate but it's pretty difficult to deny that the earth is getting hotter.

I am all in favor of responsible stewardship. But whether we're responsible for something bad, whether something bad is happening, or what to do about it is, you have to admit, unknown.

It is fact that Mars' icecap melt and temperature rise coincides with earth's.

It is also fact that NOBODY is doing Kyoto, whether the USA signs on or not.

What are we to make of all this? I'm waiting patiently for the specialists while the general facts point to the conclusion that there's nothing to do at present other than shoot all our politicians so that we can hear the truth quietly assert itself over hype.

"What are we to make of all this? I'm waiting patiently for the specialists while the general facts point to the conclusion that there's nothing to do at present other than shoot all our politicians so that we can hear the truth quietly assert itself over hype."

There is one thing that we can be pretty sure of and that is that the current increase in atmospheric CO₂ is a response to our activities. Not only is the current level higher than it has been over the last 800,000 years but the rate at which it is increasing is around 60 times greater than it has been over the same period. Considering that there has been an end to an ice age in that period and that it has the levels have never risen that fast before it a pretty good bet that mankind is responsible for the current increase in CO₂.

There is also just to much evidence to ignore that the earth is warmer now than it was at the middle of the twentieth century and that it is likely to warm further by the end of the twenty first century.

I will admit that there is currently no definitive proof that the two are tied together and that the increase in either is responsible for the other. However, things are on the change and at a rate that appears to be considerably greater than at any time over at least the last 800,000 years and probably considerably longer. If the ice cores showed that the earth warmed at a similar rate at the end of the last ice age then yes I would agree that the warming we see is more than likely natural. But that is not what we are seeing, the rate of warming is at least an order of magnitude faster and that is cause for alarm.

If we act now and clean up our energy production and consumption only to find out that it wasn't necessary then we will end up with a cleaner more sustainable existence. If we do not act and carry on with our wasteful, polluting ways and find out that is indeed us causing the problem then we are in deep and serious trouble.

The question is, should we gamble on our future, or take the path that gives us the best chance of continued survival?

PS As to shooting the politicians, can't we think of something more imaginative that just shooting them?

Hi discussion partners,

the solution is easy and it is going on straight at this very moment:

Politicians and laws argue us to burn food for heating and car driving.

Alcohol made from sugar, palm oil or rapeseedoil (canola), corn, wheat etc.

By this the price for food will rise as much as to let starve to death a considerable part of the human population of this earth.

By this the output of greenhouse effects will go down (or not if the natural sources are considered).

So the surviving population will not have problems with sea level but will have big problems of many other kinds.

Happy Easter, Pessach, Holidays

RHABE

Masu--

I have read at least two sources which state that the West Antarctic ice sheet is thinning, but that the much more massive East Antarctic sheet is getting thicker. They did not post any conclusions of net change. Since the Eastern sheet is the much larger one, and since some areas are getting cooler while more areas are getting warmer, I believe that the Antarctic question is fairly open.

A more interesting question is what would happen to the Arctic temperatures when the wide covering of ice melts. The amount of sunlight reflected back to space would decrease substantially in the summer, but wouldn't also there be an increase in the heat radiation from the open water in the winter? Perhaps someone with access to some models and computers can post their results on this.

I don't worry about gradual changes, but about those which occur because some point of instability has been passed. Then you have results that are similar to earthquakes in their magnitude. Some have postulated methane release from clathrate ices, and other phenomena.

Beyond all the hype and all the hand-wringing is the necessity for us to be more responsible in our stewardship of this earth, and leave more of its bounty for the future generations to enjoy and benefit. Our failure to do this is a true condemnation of modern society.

John M.