A challenge to non-vegetarian, if they can contradict the answer

I'm a strict vegetarian as a result, I'm always taunted. I always felt embarrassed. I always used to think that why in our religion we are asked to have vegetarian diet and not the non-vegetarian diet. As all the non- vegetarians used to tell the various benefits of non-vegetarian food. I used to feel that there should be some very strong reason that why vegetarian food is preferred. Something which can make all other reasons appears trivial. I always used to search for that reason.

But, after surfing a lot of internet I have finally got a possible answer. The very reason of why we eat food is the answer to this question i.e. the survival of the human being on this earth.
How?

I have found on many websites which says that eating meat causes increase in the global warming. Probably all the readers must be knowing that if the temperature of our earth increase by few more degrees then our planet will become like any other planet. Then, probably the aliens (if they exist) from other planets will come and search for evidence of life as we search for evidence of life on mars and moon.

All this happens because of the concept which I had read in my ninth-tenth standard. I won't go in science of the concept. But, in the laymen terms I will say that from a plant to animal and from animal to animal only 1% of the total energy is transferred.
For example:

If we need 3000 calories per day and from each plant only 1000 calories is obtained. Then we need to eat only three plants.

But suppose if we eat beef rather than plants which can give say 3000 calories. Then most of you will think that the beef is a better option. But, I would like to say that for accumulating those 3000 calories we would have to feed cow at least 300 plants which means that we need more space and energy to feed one person.

Now greater the energy used, then greater will be the demand for energy and greater will be the burden on our natural fuel resources and hence greater would be the production of the greenhouse gases.

So, with greater consumption of meat, there would be more and more increase in greenhouse gases which will make the global warming condition worse.

Now, I think you all can conclude that by maintaining a vegetarian diet we are actually saving ourselves.

However, probably one may point out that what about the various diseases at which we all are at risk if eating of non-vegetarian food is stopped. To this point, I would like to say that many people in India are vegetarian and all those who take a balanced vegetarian diet with regular exercise always live a healthy life.