Australia has a huge interior land mass which is virtually uninhabited and there are vast amounts of land suitable for tree planting.
It is a politically and economically stable country.
Australia can go from being one of the largest emitters of carbon in the world (per person) to one of the lowest. It could, in a sense become the second lung of the world alongside the Amazon basin.
What is required are the resources and expertise build water pipelines and plant the trees.
We can pipe water to where it is needed in what are now arid regions. This has already been done in many countries.
They built the Kalgoorlie Pipeline across the desert a hundred years ago and did the same more recently in Libya.
There are new tree planting technologies to help get the job done more efficiently.
A mass tree planting program could see millions of trees being planted each month.