The modern idea of a manicured and weed free lawn is unsustainable.
Grass lawns require so much treatment and watering. Most lawns need 1+ inches of water each week. During the summer heat, this often has to come from sprinklers. Watering grass often uses extra water that the grass doesn’t need or waters unevenly. Fresh water is a natural resource that has limited amounts in the world. It is our job to limit our water use.
Perfect lawns also often need fertilizing and additional care. Many of the fertilizers on the market use harsh chemicals to kill weeds and unwanted lawn pests. These chemicals can seep into our groundwater which can further deplete our limited water resources.
Another layer of lawn care is mowing. Simply turning on your lawn mower is bad for our Earth. Gas lawn mowers use limited gas and oil resources. Gasoline is a very limited fossil fuel that requires tearing up the Earth in order to retrieve it. Even if you have am electric mower, the mower is still using power. Power that comes from unsustainable energy sources.

For the longest time, my husband was very firmly on team lovely lawn. Luckily, he never cared much about weeding or watering the grass. He did, however, love to mow the lawn and trim to the perfect height. Over time, I have slowly worn him down. I add more and more things to the yard that take up more and more room. He has conceded that, eventually, the only lawn left will be the small front yard.
In the backyard, I have added more sustainable items that take the place of all the grass. I added many, many gardens. Other ideas that you could add in place of grass are gardens, wildflowers, rain beds, ground covers, rock beds, or ornamental grasses. There are so many options within each of these categories that I could keep listing for days.
I recommend searching what options would work best for you and where you live. Please feel free to keep me updated!