It's actually happening now, but slowly and steadily. The biggest challenge currently is mitigating the impact on human habitats. This is why so much is being spent.
https://www.weforum.org/agenda/2019/01/the-world-s-coastal-cities-are-going-under-here-is-how-some-are-fighting-back/
Climate change and it's possible impact was acknowledged by major governments over 40 years ago - and little mitigating action has transpired over that period.
Nevernind the Disallowed salesman from the 1970's. Consider the thousands of the world's intelligentsia contained below
https://climate.nasa.gov/scientific-consensus/
