The "modest" it is referring to, is to match the lifestyle of the average European but with 40% the greenhouse emissions. It would involve significant changes in lifestyle, but more importantly a change in resources used for power generation. No more brown coal plants, no more black coal plants, not even any gas plants. Also, no more cotton or rice growing, and no more aluminium processing plants (recycled should be OK). Southern Australia already has water problems and water restrictions. The average dam storage levels for Melbourne dams is 25.7%, and they don't look like they're improving much any time soon.