Tracy - I am NOT a spanish native. I am a Brit who has been learning spanish for 4 years. I sometimes think getting answers from other learners can be as helpful as getting answers form natives. That said, what I am about to tell you could well be a pile of poop.
Han + estado + gerund (eg han estado viviendo en Argentina desde hace 4 años). They have been living in Argentina for 4 years. Han refers to specific people = "they".
When HABER operates in this auxiliary way, it means "They have" or "I have" etc. and refers to specific subjects, usually people.
With your fires.... you need the impersonal structure: "Han" does not refer to people or things as it does in the above example. There have been lots of fires means "somewhere out there in the world, lots of fires happened".
So, Haber, in your context has nothing to do with things or people. It is strictly impersonal.
It translates as:
Hay = there is / are
Hubo / Había = there was / were
ha habido = There has / have been (PS = If you google Han habido, i think you will find it is wrong. In Spanish, the impersonal is singular).
I write this reply hoping it helps - HABER drives me nuts, hence my desire to help!
Would be delighted to be challenged on all of the above from natives!!