In this article by Robert W. Kates, he mostly talks about how sustainability articles are growing, the emergence of academic fields, and the history of sustainability science. He mentions how sustainability science is primarily use-inspired, where significant fundamental and applied knowledge are put into society. Just like how we're trying to save on water, or save our planet from global warming, we are using the knowledge we gain from all of our experiences and using it to better the earth, consequently bettering the places we live in. Sustainability science is aimed at responding to normal science problems in a more sustainable approach. I agree with Robert that Sustainability is growing as we are seeing more uses for it, and the more we need it.
My take on what science sustainability science is, is that it's a science that uses our current available resources and use them to better our societies. Normal science combats problems in basic everyday lives, while sustainable science combats problems to save our everyday lives.