[adya33]

Insofar as your hear question goes
An IC engine as a whole will run Much hotter than a fuel cell one, thus the total heat being given out to the surroundings will reduce. This comparison matters. You will already be adding less heat to the system from a fuel cell car than you are already doing
In addition as said before, the emissions will not add to the greenhouse gases, thus the total warming effect will be far less.

1. No Greenhouse gases - No warming effect
2. Less heat from an F cell engine- less heat into system
result- The running of this engine will drastically cut down the warming. and the surroundings will saty cooler than if you were running an IC engine

nice explanation & thank you for that
however I wouldn't say no green house gases no warming effect
lets just say LESS WARMING EFFECT

You could have a valid point re the amt of water vapour in the air, but i dont think it will affect it that much,as to make the Hydrogen for the cells, you will have to take it out of water to start with, which will essentially more or less balance the amount of water sent out.

Hydrogen is not taken from water. rather it is taken from other means (if i remember correctly then from certain metal hydrides) & oxygen is obtained from air. Water molecule is a very stable molecule

so the water level won't be balanced, rather it will be increased (another worring problem)

It may however icrease the humidity in areas of dense population, but at the same time it will reduce the smoke and the heat generated, the air will be cleaner and breathable, and there will be no particulate suspension in the air

it may reduce the air pollution (main advantage) but it will at the same time increase humidity very much. imagine in place like mumbai humidity increasing sufficiently (don't consider one car, consider all cars in mumbai to run on fuel cells)

b- there is enogh CO2 in the atmosphere for photosysthesis to occur anyway, It was taking place before the IC engine was invented and will continue to do so

with IC engine there is ATLEAST a way to get rid of CO2 (not entire but some of it)
where can steam be absorbed & say converted into other useful form (without loosing heat into atmosphere & without disturbing water cycle)

don't forget the water cycle being disturbed

Few problems, though the level of CO2 has gone up, tree cover has gone down extensively.

that is the main cause of the problem