does any1 here have an idea when global warming started to become a major problem?

Answer 1

Regardless of what Algore says, it's not.
There was global warming and an ice age before we had cars/trucks/power plants.
A single volcanic eruption can spew as many greenhouse gasses in an hour as all the cars & trucks in the WORLD do in 10 years.
What makes us so arrogant as to think our puny contribution is the cause?

Answer 2

The premise of your question presumes that global warming is a problem. Scientists are divided that it's a problem, let alone a major problem. Your question is reasonable, though, because we simply don't have evidence to say it's a problem and therefore can't say when or where it began.

So, we can't say when because even if we do look at temperature rises (which isn't even proven), it's not known whether it's natural or not because our records don't go back that far.