Answer:
Environmental sustainability refers to the need for us as humans to use the environment in such a way that is beneficial to both us and the environment such that it is preserved for future generations.
It involves activities that use the resources on earth in the most efficient manner such that we can get as much as we can whilst preserving the most we can as well.
In the 21st century, we have seen strides towards more environmental sustainability in many ways such as the increasing investment into alternative energies.