Thread: 'Rising sea levels' and climate change? Tell me the truth?

Get your facts straight!!! The sea will rise only 20 meters. That is still enough tp cover New Orleans. Bush supported global warming and now Obama is stopping it. I hope it is not too late.

So, as we all know, we are pounded day in day out about how in 20 years sea levels with "rise 50 metres, destroying civilisation etc yada yada."

However, presumably, ice in the poles melts every year, how much of this ice melts every year? 40%? 20%? 10%? 50%? of total polar ice? I don't really know how much, that's why I am asking. But lets say 40% melts every year in summer: Does that mean that sea levels must be rising 40% of what al gore predicts it will rise if all the ice melts?
That couldn't be true, because the sea levels don't fluctuate every year (it may be a negligible amount), but ice melts and ice freezes, so what's going on?

Furthermore, they say when all the ice caps melt we will have rising sea levels, but what about all the ice already floating on the water and underwater? In the ice shelves? According to Archimedes principle, when ice melts, it should be taking up the same volume (actually less volume since water expands when in solid), so theoretically, melting ice shelves wouldn't have an effect on rising sea levels at all, more likely it would contribute to dropping sea levels.----- Of course this doesn't apply to sea frozen on land.

These are just my thoughts, am I failing to understand something?

Sea ice adds no real sea rise but land based ice does.

To quote the IPCC, during periods of the earths history when there was no land ice the sea was never more than 8m higher than current levels.

If you calculate the land based ice mass and divide it by the surface of the sea and low lying areas of land a maximum rise of 5-6m is obtained (caused mostly by the antarctic). Assuming air temperatures can warm the sea (which is normally done by the sun, not air temperatures) thermal expansion could add a couple more metres to this, matching the maximum historically observed i.e.a 8m rise. This ignores the areas of land that will rise as the ice recedes or increases in level on coral island (which is faster than the rate of sea rise). For all land ice to melt would take thousands of years and would happen so slowly we would barely notice within our lifespan. Note this ignores evaporation that would add a lowering effect, but its probably not the significent.

The IPCC predict something like 200 - 400mm of sea rise over the next 100 years with significent warming i.e. 4 degrees, this is slightly more than the natural rate and mostly caused due to thermal expansion, which is only predicted because the models assume re-radiated infrared can actually warm the sea.

Claims the sea will rise 50 - 60m are rediculous, there isnt enough ice to do it! Claims the sea will rise 6m in the next 100 years are also rediculous, this would take thousands of years as the warmest recorded temperature in the antarctic is 0 degrees, so even 4 degrees of warming wouldnt make much of a dent on it!

For example, the mean temperature at Amundsen-Scot, Antarctica is around -49.5 degrees c, would 4 degrees of warming really trigger antarctica to melt in a few years?

Such claims are nothing more than scare mongering and ignores the conclusions of the IPCC.

So relax and buy that beach front condo, Al Gore bought one recently so he cant believe his rediculous claims that much!

Get your facts straight!!! The sea will rise only 20 meters. That is still enough tp cover New Orleans. Bush supported global warming and now Obama is stopping it. I hope it is not too late.

You are correct that sea ice that is floating has no effect on sea level, and yes, most ice that melts during the summer is in fact sea ice. But land ice, as you realize, is a completely different story, and that is almost the entire picture. There is enough ice on Greenland alone to raise sea levels by some 6 meters:
http://pubs.usgs.gov/fs/fs2-00/

There is much, much more on Antarctica, but luckily no one is predicting that any significant fraction of that will melt. Parts of the Western peninsula maybe, but that's about it.

The other side of the picture is something called "thermal expansion". Basically, as water heats up, it expands--and that's about all there is to that. Expanding oceans means a higher sea level.
http://en.wikipedia.org/wiki/Thermal_expansion

Now, on a side note, there is no way in heck we will get "50 meters in 20 years." I know you were just pulling random numbers, but you should realize that the actual predictions are not even close to that. The IPCC predicts 18-59 cm by 2100. There are however some scientists who feel that these numbers may be an underestimate--mostly because we know next to nil about glacial flows on Greenland. Here is a pretty extensive summary of it, if you have the patience to read it (or you can just click where it says "bottom line"):
http://www.realclimate.org/index.php?p=427

Sea ice adds no real sea rise but land based ice does.

To quote the IPCC, during periods of the earths history when there was no land ice the sea was never more than 8m higher than current levels.

If you calculate the land based ice mass and divide it by the surface of the sea and low lying areas of land a maximum rise of 5-6m is obtained (caused mostly by the antarctic). Assuming air temperatures can warm the sea (which is normally done by the sun, not air temperatures) thermal expansion could add a couple more metres to this, matching the maximum historically observed i.e.a 8m rise. This ignores the areas of land that will rise as the ice recedes or increases in level on coral island (which is faster than the rate of sea rise). For all land ice to melt would take thousands of years and would happen so slowly we would barely notice within our lifespan. Note this ignores evaporation that would add a lowering effect, but its probably not the significent.

The IPCC predict something like 200 - 400mm of sea rise over the next 100 years with significent warming i.e. 4 degrees, this is slightly more than the natural rate and mostly caused due to thermal expansion, which is only predicted because the models assume re-radiated infrared can actually warm the sea.

Claims the sea will rise 50 - 60m are rediculous, there isnt enough ice to do it! Claims the sea will rise 6m in the next 100 years are also rediculous, this would take thousands of years as the warmest recorded temperature in the antarctic is 0 degrees, so even 4 degrees of warming wouldnt make much of a dent on it!

For example, the mean temperature at Amundsen-Scot, Antarctica is around -49.5 degrees c, would 4 degrees of warming really trigger antarctica to melt in a few years?

Such claims are nothing more than scare mongering and ignores the conclusions of the IPCC.

So relax and buy that beach front condo, Al Gore bought one recently so he cant believe his rediculous claims that much!

You are correct that sea ice that is floating has no effect on sea level, and yes, most ice that melts during the summer is in fact sea ice. But land ice, as you realize, is a completely different story, and that is almost the entire picture. There is enough ice on Greenland alone to raise sea levels by some 6 meters:
http://pubs.usgs.gov/fs/fs2-00/

There is much, much more on Antarctica, but luckily no one is predicting that any significant fraction of that will melt. Parts of the Western peninsula maybe, but that's about it.

The other side of the picture is something called "thermal expansion". Basically, as water heats up, it expands--and that's about all there is to that. Expanding oceans means a higher sea level.
http://en.wikipedia.org/wiki/Thermal_expansion

Now, on a side note, there is no way in heck we will get "50 meters in 20 years." I know you were just pulling random numbers, but you should realize that the actual predictions are not even close to that. The IPCC predicts 18-59 cm by 2100. There are however some scientists who feel that these numbers may be an underestimate--mostly because we know next to nil about glacial flows on Greenland. Here is a pretty extensive summary of it, if you have the patience to read it (or you can just click where it says "bottom line"):
http://www.realclimate.org/index.php?p=427