Is water a by product of photosynthesys?

[Mikespike]

and if so... are trees responsible for rising sea levels?

[Carlos]

The equation fo Photosynthesis is Carbon Dioxide + Water (with sunlight and Chlorophyl being present) = Glucose and Oxygen. So in fact the opposite is true, trees absorb water and convert it into something else. I think!

[jake-the-peg]

No but when trees die they tend to rot and methane is produced which is 20 times more effective as a greenhouse gas than the carbon dioxide the trees absorbed.

It's all about carbon sinks, that is where the carbon ends up, and getting it back into the crust of the earth.

Phytoplankton absorb CO2 and that food chain generally ends up on the ocean bed where it can be subsumed back into the earths crust.

Of course if seabirds eat the fish when they die the cabon gets back into the atmosphere. You could say

"Stop Global Warming - Kill a puffin!"

(That last bit was kind of tongue in cheek before I get death threats from the provisional wing of the RSPB)

[Eric Git]

Oxygen is the by product of photsynthesys, the more trees you have the cleaner the atmospher is. Poplar trees are especially good at this, the Victorians knew about them and so planted a lot of them during the 19th century in London, in the effort to clean the air.

[Dr Hungry]

Actually, water is a by product of aerobic respiration, which most living organisms do, including humans. So maybe we are to blame!

Well, in fact we are to blame of course, but not for that reason

[heathfield]

If a tree falls into water, the water level will rise.

[brachiopod]

...arrh, but if there is no-one around to hear it, do they make a splash?

[brachiopod]

And plants actually absorb oxygen and produce carbon dioxide.

At least, during the Calvin, or 'dark reaction' of the respirational cycle. The 'dark reaction' is actually a misnomer, since this process of carbohydrate synthesis continues irrespective of the presence of light. It is just that, in the asence of the photosynthetic process, the net balance in terms of CO2 absorption / production, is very slightly in the latter's favour.