Naked Science Forum
On the Lighter Side => New Theories => Topic started by: archie bishop on 01/04/2009 23:30:28
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I have reason to believe that global warming is a hoax because some scientists are saying that when the polar ice caps melt in a year the water would go up a foot now that is impossible the most it could go up is a few millimeters.
If any one else if any one supports me or contradicts me please do not hesitate to post a reply.
regards,
archie bishop
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Don't think I've heard anyone serious saying anything of the kind, actually. Can you provide some sort of context on which scientists might be saying this? "Some scientists" conveys no more information than "some guy on the bus". Or indeed "some guy on the internet".
The idea that global warming is a hoax is frankly preposterous (tho' widespread). The suggestion that it might be a misinterpretation of the data has some intellectual credibility, but a hoax? No. Scientists (well, academics) are the most startlingly (many would say arrogantly), determinedly individual collection of people I know of and there is no way so many would be going along with such a hoax (especially given the range of different sources of data involved in the synthesis) if they had a case against global warming they believed in. There are of course also those who don't think the case is made, or think it's too late to do anything anyway, or think that there's an anthropogenic effect but it's not the overiding effect, or whatever, but the idea that the mainstream view is "a hoax"? Again, no way.
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Also... the rise in sea level doesn't have to be due to the ice melting. If the temperature goes up the water will expand (well, above 4oC, anyway) so there's a good deal more scope for increased volume than just that which is tied up in the ice currently balanced on antarctica (tho' there's a good deal of that).
I don't know what the numbers are, so can't comment on the likely resulting rise in sea level for a given change in global temperature.
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Actually, if all of the ice tied up in glacier, ice caps and oceanic ice melted, It would raise sea level well over 100 feet. It has happened before, it will happen again.
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the most it could go up is a few millimeters.
Why?
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Actually, if all of the ice tied up in glacier, ice caps and oceanic ice melted, It would raise sea level well over 100 feet. It has happened before, it will happen again.
If water expands when it freezes.
http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/waterdens.html
When the ice in the oceans melts would not the sea level fall?.
Cheers
justaskin
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18,000 years ago sea level was MUCH lower - it is still rising.
All the numbers and maps can be found here:
http://ga.water.usgs.gov/edu/watercycleice.html
1.7 % of all water is in ice. If the average depth of the sea were 10,000 feet that would mean a rise of 170 feet if all ice melted. The sea isn't that deep on average - its average depth is 3790 meters (12430 ft) The rise would thus be about 210 feet.
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Actually, if all of the ice tied up in glacier, ice caps and oceanic ice melted, It would raise sea level well over 100 feet. It has happened before, it will happen again.
If water expands when it freezes.
http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/waterdens.html
When the ice in the oceans melts would not the sea level fall?.
Cheers
justaskin
Not all ice is in the water - ice on land would contribute to sea level rise. Also, as water increases in temperature, it's volume increases.
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I have reason to believe that global warming is a hoax because some scientists are saying that when the polar ice caps melt in a year the water would go up a foot now that is impossible the most it could go up is a few millimeters.
What is your reason or theory for this?
As others have said:
Also, as water increases in temperature, it's volume increases.
Yes, this is one of the problems associated with rising temperatures due to climate change.
18,000 years ago sea level was MUCH lower - it is still rising.
All the numbers and maps can be found here:
http://ga.water.usgs.gov/edu/watercycleice.html
1.7 % of all water is in ice. If the average depth of the sea were 10,000 feet that would mean a rise of 170 feet if all ice melted. The sea isn't that deep on average - its average depth is 3790 meters (12430 ft) The rise would thus be about 210 feet.
If you had done a simple google search, you would have found similar figures quoted on websites like the USGS. You may have even come accross an article from the USAToday, an excelent source for those who want things explained in layman terms:
Q: How much would sea level rise if the ice at both poles melted?
A: Scientists at the U.S. Geological Survey estimate that If all of the ice sitting on land in Greenland and Antarctica melted it would cause global sea levels to rise by about 215 feet, or about 65 meters.
Fortunately, even the most dire scientific, global warming scenarios do not have all of the ice melting, especially in Antarctica.
To understand what could happen as the polar regions warm up, you need to have a clear picture of how glaciers, ice sheets, and sea ice work.
A glacier, or a large ice sheet, forms when more snow falls than melts each year. As the snow falls, it compresses the snow under it, turning it into dense "glacier ice." For more on how a glacier or an ice sheet grows, see my answer to a question about the age of Greenland's ice.
As a glacier, or ice sheet builds up, the weight pushes the ice outward. A glacier in a valley will spread down the valley. An ice sheet will spread out in all directions.
The edge of a glacier can be on the water, or on land. If it's on the water, pieces break off as icebergs. On land, the edges melt and the water flows to the sea in streams and rivers.
The answer to the question: Is polar ice melting? is: It's been melting since the height of the last ice age.
The real question is: Is the ice melting faster than falling snow is adding new ice?
This is certainly the case with many glaciers around the world, mostly in regions outside the Arctic and Antarctica. It could be true of Greenland, but no one expects all of Greenland's ice to melt in this century. If all of Greenland's ice melted, it would cause sea levels to rise by about 21 feet, or 6.5 meters.
Melting of Antarctic ice would supply the rest of the 215 feet of sea level rise from melting polar ice.
The good news is that this seems highly unlikely, certainly for next few thousand years. In its 2001 report on climate change, the Intergovernmental Panel on Climate Change said that melting all of Antarctica's ice would require global temperatures to be about 36 degrees F (20 C) higher than now.
This is more than three times the greatest warming seen as possible this century and is "a situation that has not occurred for at least 15 million years and which is far more than predicted by any scenario of climate change currently under consideration," the report says.(Related: The 2001 IPCC report)
Warming of the Arctic has been very much in the news recently with publication of an international report on how the climate there is changing. (Related: Report warns of rapid Arctic warming)
The report says quite a bit about Arctic ice melting. The big concern is about Arctic sea ice, not land-based ice like the Greenland Ice Sheet, which would increase sea levels if it melted.
Since sea ice is already floating on the ocean, it does not raise sea levels when it melts, but this does not mean we shouldn't worry about it.
For one thing, less sea ice means that the ocean absorbs sunlight that the ice would have reflected away. This warms the water. Also, as the report points out, less sea ice means animals such as polar bears and seals have a harder time.
Many of the reports I've seen on the melting of Arctic sea ice, both in print and on television, have maps showing the decrease in Arctic sea ice. But, most of them have not made the point that the figures show the average summer extent of the sea ice.
Normally, ice covers about 5.8 million square miles of the Arctic Ocean in mid-February, when the sun never rises over much of the ocean and is very low in the sky over the rest. As the sun comes up in the spring, ice begins melting and by mid-September would normally cover only about 3.5 million square miles.
This melting is normal. The report talks about additional melting.
Links:
Age of Greenland's ice sheet
http://www.usatoday.com/weather/resources/askjack/2004-09-01-ice-core-ages_x.htm
All about the world's ice
http://www.usatoday.com/weather/resources/coldscience/aice0.htm
Arctic Ocean hides icy puzzles.
http://www.usatoday.com/graphics/weather/gra/arctic/flash.htm
Report warns of rapid Arctic warming
http://www.usatoday.com/weather/resources/coldscience/2004-11-08-arctic-warming_x.htm
Panel finds humans responsible for warming
http://www.usatoday.com/weather/climate/2001-01-22-ipcc-main.htm
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The ice that we have now is on water which means the water had already gone up however many years ago. what i am tryng to say is how can water go up when it is already there.
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The polar ice caps are not submersed in the oceans. In some parts of the Arctic the ice stands 10m above sea level for example.
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But not all the ice is is the water, there is plenty of ice on land in Antarctica and greenland, the melting of this would raise sea levels to those stated above.
You also have to remember that "as water increases in temperature, it's volume increases" (as stated by Ben), so even the ice that is in the water can melt and still increase in volume. This does seem strange and hard to comprehend, maybe seeing it would help?
try this experiment:
What you need:
An empty, squeezy mayonnaise or ketchup bottle
Water
Food Colouring
A Straw
Plasticine
What you do:
Half fill the empty squeezy mayonnaise or tomato sauce bottle with room temperature water and add some food colouring. Put a straw through the hole in the top and push it down until it goes under the surface of the water. Seal the gap around the straw with Plasticine. Blow a little air down the straw (not too much) so that the water level rises in the straw, about five centimetres above the top of the bottle.
Watch to see if the level of the water falls – if it does, reseal around the straw. If necessary, break up any air bubbles in the straw with a skewer or cocktail stick, or add a few drops of water into the straw to top the level up. Mark the level of the water on the straw. Put the bottle next to a radiator – what happens to the level of the water? Put the bottle in the fridge – what happens to the level of the water?
http://science.org.au/nova/082/082key.htm
In its 2001 assessment of global warming, the Intergovernmental Panel on Climate Change (IPCC) projected that global mean sea level is expected to rise between 9 and 88 centimetres by 2100, with a 'best estimate' of 50 centimetres.
Higher temperatures lead to higher sea levels
A warmer world will have a higher sea level because as the land and lower atmosphere of the world warm, heat is transferred into the oceans. When materials are heated they expand (thermal expansion). So the heat that is transferred causes sea water to expand, which then results in a rise in sea level.
In addition, water from land-based ice such as glaciers and ice sheets may enter the ocean, thus adding to the rise. A point to remember is that no extra water is added to the oceans when ice floating in the ocean melts. As floating ice melts, it only replaces the volume of water that it originally displaced.
Melting or expansion?
Which contributes the most to sea-level rise – melting ice or the thermal expansion of water? The answer depends on the time-scale you're interested in. Warmer temperatures could lead to the following scenarios:
* Non-polar glaciers
If non-polar glaciers such as those in New Zealand and Norway melted, they would release water that may enter the ocean and contribute to a sea-level rise. Glaciers are rather sensitive to climate change and they could melt rapidly.
* Greenland ice sheet
In Greenland, ice increase from snowfall is balanced by ice loss from melting and the discharge of glaciers. Projections indicate that increased melting from higher temperatures would exceed any increases in precipitation. This change in the ice balance would add water to the ocean.
* Antarctic ice sheet
Nearly all of Antarctica is covered by an ice sheet that is, on average, 2.5 kilometres thick. If all the land-ice covering Antarctica were to melt – that's around 30 million cubic kilometres of ice – the seas would rise by over 60 metres! However, in the Antarctic it is so cold that even with increases of a few degrees, temperatures would remain below the melting point of ice. In fact, warmer temperatures could lead to more snow, which would increase the amount of ice in Antarctica.
* Thermal expansion
While thermal expansion is a less obvious process than melting ice (mainly because you can't see it happening) the IPCC projects that thermal expansion will be the main component of expected sea-level rises over the 21st century.
Uncertainty in estimates
It is difficult for scientists to be more precise with sea-level projections because there are a number of uncertainties:
* Greenhouse gas concentrations
While scientists agree that the levels of greenhouse gases are rising, future increases depend on many factors, including population growth, energy use and the development of new technologies.
* Climate sensitivity
Climate sensitivity is the amount of atmospheric warming that results from a doubling of atmospheric carbon dioxide concentrations. It depends on the presence of greenhouse gases, and on feedback processes from clouds, water vapour and ice. This is a significant source of uncertainty in projections of long-term climate change.
* Ocean heat exchange
Heat moves between the atmosphere and the ocean's surface. The temperature at the surface at any one time is influenced by what is going on in the ocean. Quite small changes in the transport of heat or salt can have large effects on surface temperature, and ultimately on climate. Ocean models have developed rapidly over the last two decades but accurately representing the most important ocean features remains a challenge.
* Ice
There is uncertainty about the response of the ice sheets in Greenland and Antarctica to hundreds of years of warmer temperatures. Scientists are concerned that there could be a rapid disintegration of the West Antarctic ice sheet, causing a rapid rise in sea level.
As well as these global uncertainties, the rate and magnitude of sea-level change will vary from place to place in response to changes in ocean currents and vertical movements of the land itself. In some areas, sea level may actually fall.
What is the impact of 50 centimetres?
On average, it is expected that by 2100 sea levels will have risen in most places by around half a metre. Reduced to a raw number like this it doesn't sound like too much. What impact does 50 centimetres have on anything? Maybe you'll just have to build your sandcastles a little higher up the beach.
The reality promises to be a little grimmer. In many places, 50 centimetres would see entire beaches being washed away, together with a significant chunk of the coastline. For people living on low-lying islands such as Tuvalu, Kiribati or the Maldives, where the highest point is only 2-3 metres above current sea levels, an extra 50 centimetres could see significant portions of their islands being washed away by erosion or covered by water. Even if they remain above the sea, many island nations will have their supplies of drinking water reduced because sea water will invade their freshwater aquifers.
While these islands have sizeable populations, they're insignificant compared to the tens of millions of people living in the low-level coastal areas of southern Asia. These include the coastlines of Pakistan, India, Sri Lanka, Bangladesh and Burma.
Australian coasts
Each centimetre of sea-level rise will lead to increasing impacts on low-lying coastal land. Modelling predicts the inundation would cause sandy beaches on the Australian coastline to recede by the order of 100 times the vertical sea-level rise. For example, if the sea level rises by a metre, the coastal beaches could retreat by about 100 metres unless some preventative action is taken. Given that about 85 per cent of Australia's population lives within an hour's drive of the coast, this is particularly relevant.
Floods already cause more damage in Australia than any other natural disaster, in terms of cost to the community. CSIRO researchers believe that damage costs associated with coastal flooding would more than double in southern Queensland and northern New South Wales if sea levels were to rise by 40 centimetres.
Low-lying coastal ecosystems, such as the freshwater wetlands that make up about 90 per cent of the coastal zone of Kakadu in the Northern Territory, are also vulnerable. Hundreds of species of birds, reptiles and amphibians depend on these freshwater areas. Intrusion of salt water is already a major management issue in Kakadu. If sea levels around Australia rise by about 50 centimetres, these freshwater wetlands will become saltier. A 1-metre rise in sea level would transform lowland Kakadu almost totally into mangrove forest.
Future planning should take global warming and consequent sea-level rises into consideration. For example, building protective sea walls and restricting coastal development in areas at risk are planning measures that could minimise damage from rising sea levels over the next century.
A changing world
Even if greenhouse gas emissions could be stabilised by the end of the 21st century, sea-level rise from ocean thermal expansion may only have reached half its eventual level by the year 2500. To minimise the impacts of climate change, we need to start changing our habits as soon as possible – Australia is one of the largest per capita greenhouse gas emitters in the world. The longer we delay, the less effective our actions will be.
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The polar ice caps are not submersed in the oceans. In some parts of the Arctic the ice stands 10m above sea level for example.
Sort-of. Any ice-cap which floats of water will displace its own weight of the water that it floats in.. that is, the amount of ice in an iceberg which sticks up above the water is in effect the difference between the volume of that weight of ice and the volume of the same weight of water. So the arctic ice melting won't of itself affect sea levels, it's the ice sheets currently balanced on land (greenland, antarctic) that is expected do that, along with the expansion of the water as it warms up.
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Exactly - that's why my gin and tonic doesn't spill when the ice melts. Not that it ever lasts long enough....