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Where does all this extra water come from?

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pdq1 | 13:49 Mon 26th Nov 2012 | Science
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Many countries like Britain are now deluged with enormous amounts of rainfall yet we still talk about rising sea levels. Admittedly some rainfall is redistributed back into our rivers but the land areas are massive so absorbing much of the rest. Extra global water cannot be created so does this mean its natures way of creating equilibrium so that the melting of the ice caps does not raise the sea levels?
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There are a few factors towards raising sea levels

Melting icecaps in Greenland and Antarctica and thermal expansion of the oceans as average temperatures rise.

As average temperatures rise the air can absorb more water vapour which of course is a greenghouse gas itself - although a limited one because unlike gasses like CO2 it rains !

Actually the land is not absorbing as much rainfall as it used to. We are building over more of the Earth's surface in places where the soil used to absorb the water and slowly release it. Now it's just diverted via storm drains into rivers which then burst their banks further downstream.

I don't think rising sea levels is quite the major threat it was thought to be some years back, yes they're going up and places like London will be more at risk to the occasional storm surge but all those maps showing Britain reduced in outline are predicated on a major Antarctic melt and the numbers don't seem to support that as an imminant threat.
"I don't think rising sea levels is quite the major threat it was thought to be some years back..."

Ye Gods, jake, I never thought I'd see the day! Welcome to the world of realism!!

"Rising sea levels" is yet another major catastrophe that has been forecast to occur almost without doubt by various "experts". It joins the long list of potential threats to the very existence of mankind such as acid rain, AIDS, lassa fever, pig flu, bird flu, global warming (aka "climate change" now that it is not warming quite so ferociously), flesh-eating disease and many others.

All have been forecast to wipe out all, or a significant percentage, of human life; all the forecasts have been hopelessly wrong mainly due to the "experts" extrapolating short term trends to produce long term forecasts; and all have been superceded by something allegedly far more dire.
That is a strange thing to say Jake. Rising sea level is still on the agenda. While the treat is not imminent the trend continues at 3 mm per year. While that won't flood much in a decade it certainly will in a century.

Here is a graph of the measurements.
http://sealevel.colorado.edu/

The same page also shows the relationship with the El Nino Southern Oscillation (ENSO). When it rains a lot the sea level does indeed fall because so much water is on the land. This was the case for 2010/11.

Climate Change Skeptics pointed to this fall as evidence the science being wrong. Yet now we can see the levels on a steep rise.

Global temperature is still rising despite the misinformation promulgated by skeptics and lapped up and repeated by the likes of NewJudge who have no concern for the facts.
Over 70% of the Earth's surface is covered with water, so although the land area may be "massive" the water area is considerably more massive (i.e. more than twice as much).
I have no doubt that global temperatures are rising, beso. I've never denied that they are. They have risen (and fallen) in the past and they will do so again in the future. What I (and many others) am "skeptical" of is the cause.
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Lots of knowledgable answers to get my teeth into, Thanks.
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Beso's link makes interesting reading. It states during 2010 the mean sea level rise dropped 5mm. ie

///large volumes of water from the oceans to the land surfaces also helps explain the large drop in global mean sea level in 2010///

So if the capture of most of this rainfall in land reservoirs could be made not only would it solve our intermittent water shortage but handle the sea level rise to normal limits. The excess water we don't need could be taken by tankers to parts of the world that suffer water shortage. Maybe just a pipedream!
Where are you going to get the trillions of tankers, at what cost. and the roads to carry them, then the ships to carry them all over the world PDQ1?
Don't forget the water behind dams. China's Three Gorges Dam is probably holding back enough water to keep sea levels a measurable amount lower than they would have been if the dam had not been built. You might say that huge numbers of dams, with the potential for hydro-electric power and holding back sea-levels, could be the answer to prayer. But,as someone here is bound to point out, the rotting biomass caught behind dams can give off more CO2 than the hydropower saves. And no, the same biomass does not produce the same CO2 if it reaches the sea.
PS we might try re-flooding the dried-up seas like the Aral sea. Divert a few rivers, maybe, for a few years.
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As I said Toureman just a pipedream However if you ever happen to travel to East Anglia notice the hundreds of miles of man made canals with sluice gates which were made to cope with past floods. A place they forgot though was Welney where the road is often impassable due to heavy rain. Historians can travel to the Boston stump near the Wash and see markings on the side of the church where previous floods have risen to.
It said on the news last night that the land is so saturated from the wet summer that they are not absorbing any of the current rainfall.
In 2010 an area of Australia the size of France and Germany combined was flooded. Indeed the Australian coastline was quite a different shape in the Gulf of Carpenteria.

Vast areas of Thailand were under water early this year.

However one of the significant contributions to sea level rise is the extraction of ground water. Last year India extracted over 70 cubic kilometres of ground water. Clearly this is unsustainable.

The extraction of groundwater is also a major contributor to the subsidence of some land areas.
Kiribati is in the area where the sea level is rising the most.

Most of the sea level rise is due to thermal expansion. The tropical seas are warming rapidly so the thermal expansion is greatest in the tropics.

I suspect that many tropical islands have extracted a lot of ground water too.

Another problem they have is coastal erosion by increasingly violent storms fueled by the extra heat.
Unsure I understood the question. We may be getting increased rainfall but how does that relate with a "yet" to rising sea levels ?

Yes rain on the landmass sinks in to raise the water table. But that has always been the case. "Nature's Way" is a misleading phrase, nature does not work out an intent. It just is what it does.

Rising sea levels, if I understand it correctly, would be down to water trapped as ice presently on top of land mass, melting and running into the sea.

I think you may be creating inappropriate connections between different activities. I don't believe one will have a major affect on the other.
NewJudge. The rate rising temperatures are unprecedented in geological history.

These rates closely conform with the computer models which attribute most of the increase to the forth percent rise in the level of carbon dioxide in the atmosphere since industrialisation of the world.

You deny the connection because you refuse to acknowledge the science.
... forty percent rise in atmospheric carbon dioxide.
I don't deny the connection, beso. I don't accept it either. All the evidence I have seen suggests that a number of causes may lead to the small increase in global temperatures we have seen in the past few years. The truth is that nobody knows (or is ever likely to know) what the real cause is.

What I do know is that the hysterical over-reaction of a few, mainly European, governments to the phenomenon is out of all proportion to the net result that their knee-jerk policies will produce. Governments which include a "climate change" minister are suffering delusions of grandeur. Building a few wind farms here and there and turning off a few miles of motorway lights will not change matters one iota when China is opening new coal-fired power stations at the rate of one a week.

So I guess we'll have to agree to differ. One thing I do know is that neither I nor any of my successors is likely to die for any reason connected with global warming unless, that is, I'm involved in a road accident because the street lights have been switched off in order to "save the planet".
No this isn't true

It is crtain that Human activity has lead to a rise in the Earths overall temperature - the problem is to see this evidence you have to examine it mathematically with the computer models.

That's why the vast majority of skeptics are those with little or no real scientific background and why *ALL* the world's scientific institutions say that this is the case.

What is uncertain is how great the effects will be and how they will manifest themselves is small areas of the globe like the UK.


Unfortunately the internet provides a mouthpiece for a lot of opinion that is not qualified by proper scientific process and those wanting to distrust the science latch on to this and use it to spread doubt in the way you see here.

We have one of the worlds oldest and most trusted scientific institutions in the world here - the Royal Society.

http://royalsociety.org/policy/climate-change/

they say

It is certain that increased greenhouse gas emissions from the burning of fossil fuels and from land use change lead to a warming of climate, and it is very likely that these green house gases are the dominant cause of the global warming that has been taking place over the last 50 years.

If you can find a serious scientific institution that disagrees with that (rather than an article in the Telegraph) I'd love the reference

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