There is a popular myth that population growth alone determines our impact on the environment.[1] In reality though, it is the combination of both the population size, as the (degree of) participation of each member on the economy, as the way in which each member chooses to use this wealth that determines this.[2]
That being said, the decision of not reproducing is one of the most effective actions we can take. In practice, some families will be able to propagate and some not as we are all entitled to about 0,57 children.[3][4] This does not mean of course that we can not have any children at all, because adoption is still an option, as this does not increase the population size.