Socialism

One of the core problems with capitalism is that it's fundamentally based on growth and consumerism. Companies need to constantly sell products in order to continue to operate and this leads to things like planned obsolescence where goods are intentionally manufactured to break so that new ones could be sold. This is just one of countless examples of perverse incentives that capitalism creates.

On the other hand, socialism creates a completely different incentive structure. Things are produced based on societal needs, and producing things is seen as a cost. This creates incentive to make things that last, and that can be repaired. Here's a great article explaining how this worked in practice in USSR.

So, while socialism alone doesn't ensure sustainability, it doesn't create perverse incentives that capitalism creates, and it makes it possible to have a sustainable economy.