I know that there are differences between increase and increment and decrease and decrement in general. E.g. increase/decrease can be used as verbs whereas increment/decrement cannot, and increment may not necessarily imply an increase in some contexts (Mathematics). 

However, I am not aware of any differences in meaning between them when used as a noun in a context similar to this:

> 
> The expected increase in global temperatures 
>  vs. The expected increment in global temperature
> 
> 
> 

I checked the usage in the English corpus with Google Ngram Viewer and the pair increase/decrease seem to be used more frequently.

Is there a subtle difference in meaning between these two? Would there be a subtle difference, if I used decrease and decrement in the previous comparison?

[![Decrease vs Decrement](https://i.stack.imgur.com/7uxbO.png)](https://i.stack.imgur.com/7uxbO.png)

[![enter image description here](https://i.stack.imgur.com/WhVwo.png)](https://i.stack.imgur.com/WhVwo.png)