Economic growth can occur while simultaneously becoming more efficient with existing resources. See the massive gains in agriculture, for example. An acre of land today can produce vastly more food than an acre could 500 years ago, for example.
Adding more inputs to a production process generally increases output. But many parts of the world are already suffering from soil depletion because of intensive farming, and the fertilizers and fossil fuels which we use to raise yields will run out eventually.
Innovation has been able to outrun resource depletion for the last 300 years of industrialism, but that is no guarantee that it will last forever. Even a lot of that growth has come at the cost of increased emissions and resource depletion rather than efficiency gains.
> Innovation has been able to outrun resource depletion for the last 300 years of industrialism.
It did over hundreds of years of EXTREMELY high growth (both in terms of number of people and wealth per person). If growth falls to a positive-but-very-low level, it will make it a lot easier for innovation to keep up.
Also, keep in mind that apart from Uranium, all the atoms on Earth remain here. We don't "use up" atoms at any significant rate. Apart from the atoms themselves, the main challenge is how they're put together. To rearrange how atoms are put together (to create fertilizer, recycle waste, etc), we primarily need energy. And before energy resoures run out, we should be able to produce suffient amounts of energy using either renewables or fusion.
Now fusion could cause us to face a situation where we run out of hydrogen atoms, but at the rate we currently consume energy, that would take practically forever.
In any event, in about a billion years, the sun will become a red giant.
