Attribution of the Australian bushfire risk to anthropogenic climate change

Same study discussed here a few weeks ago:

https://news.ycombinator.com/item?id=22492538

I thought the headline was hard to understand so I found where the 30% number came from in the article:

> Four climate models for which FWI could be calculated show that the probability of a Fire Weather Index this high has increased by at least 30% since 1900 as a result of anthropogenic climate change.

I’m surprised it’s not 100% more likely given what we know based on evidence ?

When will we get past even bothering to ask the question of whether or not it’s because of humans? It’s starting to seem very dated.