According to 2 Thess. it will mean climate change.
Some of the conditions described in the Revelation could match up to global cooling.
But more to the point of the op, Revelation has different sections, the first, the letters to the churches, deals with things that are or were about to be.
The second deal with future events.
When the Revelation was written the destruction of 70 AD had already happened.
Here it is good to remember that there has not been just one day of the Lord where something of monumental importance happens.