So i've heard this a few times in the past couple of days & really had no argument. I need one.

 I've heard people say that life here is so fragile on earth. If the earth was just 1 degree closer to the sun then all of the water would boil away & if it were 1 degree farther it would freeze. Inhibiting life as we know it.

Well... If i'm not mistaken (i'm pretty new at this astronomy hobby) the earth isn't orbiting the sun in a perfect circle so it would have to be closer to the sun at some point & farther at another point correct?....Can someone further exlplain?

I think perhaps what was meant was that if the average annual temperature were to change by one degree either way we'd suffer those consequences. If the Earth were nearer the Sun at the closest point in its orbit, or further at its most distant point, then the average annual temperature would change.

However, I doubt the range is that small. I recall reading that when Greenland was "green" the Vikings settled it, then the "Little Ice Age" descended on them and the average annual temperature dropped by 1/2 degree and Greenland was covered by ice, crops failed, and they all starved.

So, it doesn't take much of a change to cause trouble.

However, if the temperature is not too extreme for life to form in the first place, it's probably adaptable enough to survive at average annual temperatures within a few degrees of what we experience here.