To sustain the current amount of humans, we are using unsustainable methods. That makes us unsustainable as well.

Some estimates from Wikipedia: “Climate change, excess nutrient loading (particularly nitrogen and phosphorus), increased ocean acidity, rapid biodiversity loss, and other global trends suggest humanity is causing global ecological degradation and threatening ecosystem services that human societies depend on.[9][10][11] Because these environmental impacts are all directly related to human numbers, recent estimates of a sustainable human population often suggest substantially lower figures, between 2 and 4 billion.[12][13][14] Paul R. Ehrlich stated in 2018 that the optimum population is between 1.5 and 2 billion.[15] Geographer Chris Tucker estimates that 3 billion is a sustainable number, provided human societies rapidly deploy less harmful technologies and best management practices.” en.wikipedia.org/wiki/Sustainable_population