Is the polar ice melting?

  octal 22:15 17 Aug 08
Locked

This article seems to suggest otherwise click here

Does that mean that the sea level is going to remain the same for the foreseeable future? I suppose we will have to wait and see, because the so called experts can't seemed to agree, anyway, I don't think they have a clue themselves.

I can remember back in the 1970's they were suggesting that we were entering a new ice age, it's difficult to decide who to believe.

  Forum Editor 23:56 17 Aug 08

than the extent of the ice is its volume. I'm not for a moment suggesting that the information in your link is wrong, but it refers to the area covered by ice, rather than the total volume.

Sea levels have been rising for quite a long time, but very slowly - around 1 to 1.5mm a year on average over the last 100 years. In New York, for example, tide gauge measurements show sea levels are currently rising by 2.73 mm a year, and nobody knows whether that will continue at the present rate,or increase. The rise in levels isn't necessarily wholly attributable to melting polar ice; as temperatures rise the oceans are subject to thermal expansion - the volume of the sea water becomes greater as it warms.

Thermal expansion isn't the only answer however. Between 1880 and 1980 world sea levels rose by between 100 and 150mm, and thermal expansion is estimated to account for no more than 20 to 50mm of that. The rest must have come from somewhere, and the only source that could supply that amount of water is ice - melting glaciers and melt water from the polar ice caps. We are talking about huge volumes of water here; it's been estimated (by the US geological survey) that the Greenland ice cap alone contains enough water to keep the Mississippi river flowing at full bore for over 4700 years.

Estimates of the volume of ice in Antarcta vary between 6 and 7 million cubic miles (it has an average thickness of 7000 feet), and if that little lot melted sea levels would rise by about 200 feet all over the planet.

Who knows what's really going on? The answer of course is nobody. All we can do is observe and record what happens, and what's happening at the moment is that temperatures are rising - of thet there's no doubt. Over the 100 years ending in 2005 global air temperatures rose by an average of around 1.3 degrees F, and most scientific bodies are in broad agreement that since 1950 most of the increase is attributable to the so-called greenhouse gas effect.

Land temperatures rise faster than oceans because the seas can lose heat faster by radiation. That accounts for the fact that the Northern hemisphere is warming faster than the Southern - it has a greater land area.

Our planet has been through many warming and cooling cycles in the past, and it may be that our present situation is the result of one of these blips, probably made worse by our activities. When it will change is anyone's guess, but change it will, and let's hope our ancestors are around to witness it.

  carver 00:00 18 Aug 08

Similar story here, click here

Same old thing, if it doesn't fit in with the global warming theory, ignore it.

What has the "war on terrorism" and the "global warming" hype got in common?

One increases the price of oil, the other justifies it.

There is so much money tied up in the global warming theory that even if a 100 scientists could prove it was wrong they would all be classed as mad.

  Forum Editor 00:12 18 Aug 08

The fact that the world is warming is just that - a fact, not a theory. The world is getting warmer, and as far as I know nobody seriously disputes it.

The debate is not about whether there is warming, but about why, and what - if anything - we can do to minimise the impact and/or halt the warming. The warming doesn't justify the increase in the price of oil - I don't see how you work that out. Oil prices are increasing because we're using more, and we're finding it increasingly expensive to extract. There's lots of oil in the world, but it's becoming harder to get at.

  DrScott 01:39 18 Aug 08

is that the North Pole icecaps cannot contribute to rising sea levels: the water displaced by the mass of ice does not increase as the ice melts.

It's when ice melts on land mass that one can wonder as to rising sea levels.

I thinking melting north polar ice has only ever been used as an indicator of global warming - if it's expanding, it makes one wonder as to whether it is an accurate indicator.

  Forum Editor 07:47 18 Aug 08

There is of course a good deal of ice on land masses. The other factor is that sea water is warmer than ice, and as ice melts into the sea it is subject to thermal expansion - the volume of the oceans increases slightly. As global air temperatures increase, thermal expansion increases, and so sea levels rise more. It's a slight increase, as I mentioned before, but it's a real one.

  AL47 08:48 18 Aug 08

dont worry when the atlantic conveyer shuts down the see level will ffall again ;)

  Noldi 11:45 18 Aug 08

One point that I think is seriously missing regarding this planet warming is,

The centre of this planet is very hot and the heat transfer to the surface may have increased because a layer of oil is being removed and allowing the surface to heat up, as a Engineer I know that oil does not transfer heat as efficiently as some other fluids water etc, I have read nothing on this theory only on what is coming from above has anybody seen anything on this type of theory.

Noldi

  lofty29 12:45 18 Aug 08

All I know is that I wish they would send some of the GW down here to devon its B***y freezing

  Forum Editor 17:30 18 Aug 08

All the oil that has ever been removed from the ground would only represent a minute fraction of 1 percent of the total volume of the earth's crust. The earth isn't warmed from within, it's heated by solar radiation. If the sun's light was excluded from the planet's surface for even a fairly short period - say six months - the seas would rapidly be covered with ice, and all life on earth would quickly cease to exist. Temperatures would plunge too low to support life as we know it, and the earth's core would provide next to no heat at the surface.

  Wilham 17:56 18 Aug 08

Noldi
If the oil were that effective as insulation in the Earth's radial temperature gradient, then by now it would be a major tool in oilfield search.

DrScott
You rightly point out North Pole ice cap melt doesn't affect sea level. I suggest this Achimedes principle will also apply to the 2000 times as thick Greenland ice, and the land support will rise with the tectonic plate, which floats in magma.

FE
Water at freezing point contracts when it warms to to about 4C, and expands thereafter. This property obstructs warming convection currents around the ice, delaying the melt.
I think some of your data just isn't reliable. When I moved to be head of maths at my second Grammar School I knew maths in Geography was a bit odd, but I could just leave them to it. In the late 50's Geography syllabuses began bringing in statistics as part of modernisation. As head of maths I had to explain such as chi-squared and similar tests. Problem was that all they wanted to do was apply a formulae without understanding origins and limitations.

I'll get to the point. FE writes...
"Over the 100 years ending in 2005 global air temperatures rose by an average of around 1.3 degrees F, and most scientific bodies are in broad agreement that since 1950 most of the increase is attributable to the so-called greenhouse gas effect."
To work out the average daily temperature, max and min, mercury thermometers were suspended horizontally in a vented box. (Stephenson screen?)
The readings were noted. The average temp was taken as the arithmetic mean of max and min.
This is fine as long as it's understood Geography average has not the same meaning as in other fields. It is misleading because a long hot day may be at near max most of the time, and the night a short, sharp dip to near freezing. It is no foundation for claiming a 1.3F increase in average temperature rise in 100years.

In brief, two more items...
That change in sea-level at New York... When sea-level rise over a period is given, tectonic plates also can move, and vertical shift in height of the land base ref. position can affect the accuracy. How much has the height of NY changed, or do we just know the land/sea level change?

Finally, FE says most scientific bodies accept that global warming since 1950 is mostly attributable to greenhouse effect. I believe CO2 is a result of global warming, not the cause. But to put my case I'd need the reader to comprehend how a drop of pure water is unstable below a certain size. What is the Brewster angle in optics? How does the Wilson Cloud Chamber work?

All are simple to understand but take time, and I've gone on long enough. W

This thread is now locked and can not be replied to.

Sniper Elite 4 review: Headshotting Nazis has never felt so good

1995-2015: How technology has changed the world in 20 years

The Fresh New Fonts of 2017

WWDC 2017 dates: How to get WWDC 2017 tickets, when is WWDC 2017 and more details announced