Can we use 'what' as a reference to a previous statement?

Solution 1:

Using what as a relative pronoun, in this way, is a frequent error, made in some regional dialects e.g. Cockney.

It's the Sun wot won it was a famous banner headline in the Sun newspaper, following the Conservatives' unexpected victory in the 1992 General Election. It mimics the way some working-class Cockneys speak.

There are circumstances in which what is correctly used as a relative pronoun in standard English, where it refers to the things which. But as this grammar linkindicates, it should not be used to refer to a preceding noun.

Solution 2:

I believe you can I if you split the sentence into two statements. Such as, “The weather is getting warm. What indicates spring is approaching.” What used as ‘the thing that’. The thing being the process. What, refers to the entire meaning behind the first sentence. Hence, “The weather is getting warm. What (The process that) indicates spring is approaching.”