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Does the earth have more or less water now than 1000 years ago? Homework - can you help?

(14 Posts)
carriemumsnet (MNHQ) Wed 10-Sep-08 22:16:45

Part of dd's homework due in tomorrow...says please explain...

Is this a trick question - is there not the same amount (cost it evaporates and comes back down again?? (this is 9 yr old's homework on water cycle .. so that's what made me think that)

Dh says there;s more cos ice cap melting and sea levels rising

sister says less cos more deserts

9 year old has gone to bed and I'd love to follow her

Can anyone help??

Madlentileater Wed 10-Sep-08 22:19:08

overall amount of water unchanged.
form it's in may have changed.

Jojay Wed 10-Sep-08 22:20:08

What madlentileater said smile

carriemumsnet (MNHQ) Wed 10-Sep-08 22:20:57

yay does that mean I win?

carriemumsnet (MNHQ) Wed 10-Sep-08 22:25:05

when I say win.. I mean finish doing homework so I can go to bed early in order to get up at ungodly hour to ferry same dd to netball practice hmm

Thanks all, knew I could rely on Mumsnet when google failed smile

Madlentileater Wed 10-Sep-08 22:27:50

night night!

SmugColditz Wed 10-Sep-08 22:29:39

It's the same, it's just moved. It hasn't left the planet.

Like if she puts all her toys away in her room, she doesn;t have no toys left, they are just somewhere else.

carriemumsnet (MNHQ) Wed 10-Sep-08 22:31:01

Night all

Reallytired Wed 10-Sep-08 22:33:06

Depends what you mean by water. If you mean liquid water as opposed to ice then the earth had less water.

Over the last two hundred years sea levels have been rising and low level glaciers like the Mer de Glace in France have been melting.

http://www.sciencedaily.com/releases/2007/05/070516101548.htm

Polar ice caps are shrinking.

http://www.kidzworld.com/article/7238-polar-ice-caps-here-today-gone-tomorrow

What is harder to know is whether the ice caps have been just shrinking in the last 200 years or over the last 1000 years.

Certainly 2000 years ago England was warm enough for the Romans to grow wine. However in the past century the river Thames froze over and people could skate on it.

http://www.londononline.co.uk/history/thames/3/

There have been climate variations in the past without global warming.

http://www.telegraph.co.uk/news/uknews/1533290/Climate-chaos-Don%27t-believe-it.html

Its not an easy homework

deegward Wed 10-Sep-08 22:34:08

ooo saw this and thought I can answer this, seen that it has already been answered sad.

But I'll put my twopenneth in anyway,

You can neither make not destroy mass it only changes (?) think that was physics?!

GrimmaTheNome Wed 10-Sep-08 22:36:56

Of course theres a small amount orbiting round in the bodies of the space station crew but dont suppose thats what teacher meant.

Or whether any icy comets have made impact in the last millenium...

Reallytired Wed 10-Sep-08 22:41:22

Water can be broken up by chemical reactions. But then volcanos can produce hydrogen and oxygen as well as lots of othe nasty gases. Or possibly primative bateria might produce water in chemical reactions.

http://en.wikipedia.org/wiki/Originof_water_onEarth

I just wonder how the teacher would cope with this homework. Its not easy.

snorkle Thu 11-Sep-08 09:53:42

I suspect there is more water that 1000 years ago, because a key chemical reaction that we do a lot of (burning hydrocarbons) produces water.

snorkle Thu 11-Sep-08 09:53:42

I suspect there is more water that 1000 years ago, because a key chemical reaction that we do a lot of (burning hydrocarbons) produces water.

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