Thread: Sea levels as per ice caps?

Originally Posted by wyly

millions of years! I was worried for moment I was thinking "well, there goes the neighbourhood the Ozzies are moving in next door"...

Yeah! And here was I hoping for cheaper air fares - always wanted to see that famous Canadian Yellow Snow!!

Thanks all. This was a GREAT discussion. (And I learnt a lot from it.)

Originally Posted by MannieD

It is not just the melting of the ice on land that causes a rise in sea levels. Thermal expansion of the water is responsible for about 25% of sea level rise. source

Yup. There's also the fact that sea ice is only primarily underwater. Some of it is above the surface, and there's a lot of it, so if it all melted the result wouldn't be trivial.

More importantly, water is most dense at 4 degrees C. Any colder and it takes up more space. Any warmer, same thing. The areas reclaimed and covered by water will be relatively shallow compared to the deep ocean. Most of them will have an air temperature of a lot more than 4 degrees, so the water won't take long to catch up. The whole thing snowballs (for want of a much warmer term.)

This has happened before, and even if every worst case climate prediction is completely wrong it will happen again, eventually.

Any idea what such a catastrophic rise will do to freshwater? Not just lakes, but the water table?

Originally Posted by Bowerbird

Yeah! And here was I hoping for cheaper air fares - always wanted to see that famous Canadian Yellow Snow!!

If you ever do...get yourself a good goose down coat.

Granny wonderin' what dey gonna do when alla Australia under water?...

Rising seas create crisis for Australia’s beachfront
Mon, Jul 23, 2012 - When Elaine Pearce left Sydney for the seaside peace of Old Bar 12 years ago she was assured her new house was a solid investment, with a century’s worth of frontage to guard against erosion.

But three neighbors have already lost their homes to the rising ocean and there are scores more at risk as roaring seas batter the idyllic beachside town, ploughing through 40m of foredune in just eight years. “I wanted water frontage, and frontage I’m going to get,” Pearce joked. Property values have dived along her once exclusive cul-de-sac, with homes once worth A$1.5 or A$2 million (US$1.5 or US$2 million) now abandoned and offered for A$300,000. Weathered “For Sale” signs dot the sidewalk.

UNWANTED

Insurers will not cover homes for erosion and long-time local resident Allan Willan said the banks were even struggling to sell off the land on which the repossessed homes stand. “They can’t even give it away,” said Willan, who estimates that another 5m of frontage could “easily” be lost in the next storm period. “If it continues at this rate in seven years it’s going to be at the front door,” he said.

Old Bar is the most rapidly eroding and at-risk piece of coast in populous New South Wales (NSW) state, losing an average 1m of seafront every year and far outstripping other areas in terms of property at risk. Andrew Short, director of Sydney University’s coastal studies unit and a government planning advisor, said the 4,000-person town was among the worst erosion sites in Australia, with huge volumes of sand routinely lost in storms.

HOT SPOTS

Currently there are 14 similar “hot-spots” along the densely populated NSW coast — a region home to some 5.8 million Australians — with about 100 properties at risk. However, Short said “many hundreds of properties, if not thousands” would be at risk in the next 50 to 100 years as sea levels rise due to climate change, with planning authorities factoring in a 1m increase over the next century.

Australia’s government estimates that more than A$226 billion in commercial, industrial and residential property and road and rail infrastructure is at risk from erosion and inundation by 2100. That forecast includes 274,000 homes.

Old Bar has been in the grip of an unprecedented storm period, in terms of both frequency and strength, and University of New South Wales oceanographer Matthew England said it was a trend likely to intensify. “The sea level rise is one thing, but we’re expecting storms to become more intense and storm surges are what really hits these low-lying coastal communities,” England said.

RISING WATERS

Originally Posted by waltky

Granny wonderin' what dey gonna do when alla Australia under water?...

Rising seas create crisis for Australia’s beachfront
Mon, Jul 23, 2012 - When Elaine Pearce left Sydney for the seaside peace of Old Bar 12 years ago she was assured her new house was a solid investment, with a century’s worth of frontage to guard against erosion.

What a load of tripe. They blame bad weather erosion on rising sea levels. They then call the weather event which is a strong ENSO that happens about once a decade to a once in a century event when it is actually a rather cyclical once ever decade event.

Originally Posted by wyly

millions of years! I was worried for moment I was thinking "well, there goes the neighbourhood the Ozzies are moving in next door"...

Don`t be too concerned, we are a fairly easy going & tolerant people. I`m sure some kind hearted Aussie would teach you how to eat with a knife & fork. - wink

This is actually one of my favorite things to think about, geology. Because it occurs on such vast time frames that most people can't even think of it.

As far as what sea level changes will mean, you have to consider the evolution of our planet itself. At one time, the surface was completely covered by water. But the water did not go anywhere, it was pretty shallow. When the planet was new, the crust was not thick enough to form the mountain ranges that we are familiar with today, that took many hundreds of millions of years to develop.

Then we had several differing eras. Global Ice Ages ("Snowball Earth"), super continents, then the thickening of the crust and the eventual continental conveyor belt that is modern Plate Tectonics.

What we have now bears little resembelence with the planet of 3 billion years ago. Our original continents were pretty flat, which led to appearance, dissapearance, and re-emergence of inland seas many times over the eons. And as time progressed, features like the great mountain ranges became both more common and larger.

What is believed to be one of the first "Mountain Ranges" on the planet is the Central Pangean Mountains. These rose in a rather odd place, the center of the continent of Pangea. It is believed that crust buckling as the continents of Laurussia and Gondwana slamed together to form Pangea, and it was at the time the largest mountain range on the planet.

And these mountains were impressive, at the time. Towering maybe 4,000 feet, these were giants, where as today they would barely be worth mentioning. And they still exist, in the US they form the backbone of the Appalachians, they are also the Little Atlas Mountains in Morocco, and also the Scottish Highlands. But they are nothing compared to the Alps, or the Rocky Mountains to come later.

Part of the problem we get in this is that people seem to think that sea levels are fixed. They most certainly are not however. Sea levels have been rising for the last 30,000 years, and show no sign of changing that any time soon. Venice was once on dry land, and most of Denmark was dry land also when it was founded. Now thousands of years later it is taking increasingly heroic measures to keep these areas from sinking below the seas.

However, many areas that were once underwater will not be so again. The Great Plains of the US is now at a higher elevation, thanks to the buckling of the North American Plate. In fact, many areas of the ancient seas are now at an elevation of a mile or higher over sea level (like the coral reef near Carlsbad Caverns).

There are local variations. The weight of a mile thick coating of ice being removed from northern Britain has resulted in a rebound, where the landmass in the North is rising like a slow-motion cork bobbing on the water, and the South is dipping down a little. Despite that, we can see from Roman quayside and jetty remains that sea levels in Poole Harbour, Dorset at the time of Christ, were six feet or more lower than they are today.

Originally Posted by Mushroom

This is actually one of my favorite things to think about, geology. Because it occurs on such vast time frames that most people can't even think of it.

As far as what sea level changes will mean, you have to consider the evolution of our planet itself. At one time, the surface was completely covered by water. But the water did not go anywhere, it was pretty shallow. When the planet was new, the crust was not thick enough to form the mountain ranges that we are familiar with today, that took many hundreds of millions of years to develop.

Then we had several differing eras. Global Ice Ages ("Snowball Earth"), super continents, then the thickening of the crust and the eventual continental conveyor belt that is modern Plate Tectonics.

Plate tectonics happened fairly early in the Archean era

What we have now bears little resembelence with the planet of 3 billion years ago. Our original continents were pretty flat, which led to appearance, dissapearance, and re-emergence of inland seas many times over the eons. And as time progressed, features like the great mountain ranges became both more common and larger.

What is believed to be one of the first "Mountain Ranges" on the planet is the Central Pangean Mountains. These rose in a rather odd place, the center of the continent of Pangea. It is believed that crust buckling as the continents of Laurussia and Gondwana slamed together to form Pangea, and it was at the time the largest mountain range on the planet.

And these mountains were impressive, at the time. Towering maybe 4,000 feet, these were giants, where as today they would barely be worth mentioning. And they still exist, in the US they form the backbone of the Appalachians, they are also the Little Atlas Mountains in Morocco, and also the Scottish Highlands. But they are nothing compared to the Alps, or the Rocky Mountains to come later.

Hmmm - love to see a link to back this up

Part of the problem we get in this is that people seem to think that sea levels are fixed. They most certainly are not however. Sea levels have been rising for the last 30,000 years, and show no sign of changing that any time soon. Venice was once on dry land, and most of Denmark was dry land also when it was founded. Now thousands of years later it is taking increasingly heroic measures to keep these areas from sinking below the seas.

Yerrrsssss but Denmark??? Don't you mean Holland??? The problem in Venice is not that the water is rising so much as the land is sinking

However, many areas that were once underwater will not be so again. The Great Plains of the US is now at a higher elevation, thanks to the buckling of the North American Plate. In fact, many areas of the ancient seas are now at an elevation of a mile or higher over sea level (like the coral reef near Carlsbad Caverns).

And conversely many areas that WERE dry land have sunk and are now in danger of being deluged