It's a pretty silly and loaded shockjock question and I'm guessing there's not any climate change ' protetors ' posting on hc to reply, so I'll have a go at answering it myself.
How can we prevent a bushfire that is already history by something that we are going to do in the future ?
Let's suppose that renewables were developed enough for Australia to be powered by 100% renewables. I'm not sure it will ever be 100%. Maybe 80 or 90 % but let's go with 100% for the discussion's sake seeing as you posed the question.
That means we would have developed massive renewable resources. Really large offshore windfarms. Really large solar farms in remote areas such as the Pilbara. Really large green hydrogen plants. Really large energy storage systems. Pumped hydro, compressed air, industrial sized flow batteries etc.
So, at the point that we have renewable energy on that scale, energy will be really cheap. We have already demonstrated the rapidly falling price of renewable energy. There is plenty of evidence to support that . We have also demonstrated that fossil and nuclear energy is getting more expensive by the day.
I could include the cost of environmental damage from coal dust, heavy metals, global warming etc. to the cost of fossil and nuclear but I'll leave that out for the moment.
From a purely financial point of view, renewable energy will be much cheaper than fossil and nuclear.
Economies around the globe will switch to renewable energy simply because of the economics. As a result of that, CO2 emissions will drop or stop increasing dramatically.
Therefore, in answer to your question, if Australia was able to be 100% renewable, then it's highly likely that the rest of the world would have reduced it's emissions significantly. In that circumstance, global CO2 emissions would be limited or reduce and therefore the greenhouse effect would be reduced, thus lowering global temps or at least stopping them from increasing.
Less temperature increase means less extreme weather events. Less extreme droughts would mean we have reduced the amount of times the conditions for these fires could exist.
