That's an extremely negative-sum way of viewing the world. Some individual humans (and even communities) can and have had a net-positive impact on the environment. For instance, did the parents of Greta Thunberg have a net-negative impact on the world by choosing to bring her into it?
When people implicitly say that bringing children in the world is necessarily a net-negative on climate, they're implying that their lifestyle is necessarily net-carbon-positive and that they just refuse to do enough to make their own lifestyle net-carbon-negative. Yet it IS possible to do so. I'm reminded of this Indian fellow who planted an entire forest pretty much by himself (although surely his wife/family also helped enable him to accomplish that goal): https://www.youtube.com/watch?v=i7i3QlMvsZs
...there are so many decisions one can make to cut one's carbon emissions to near zero. And some decisions can even make one's carbon emissions negative (some startups at Y Combinator, even... although there are more proven methods as well).
The most powerful thing as a parent is that you can help pass on your values to your children. Teach them (through example) how to live a low or negative carbon lifestyle and teach them the value of the environment and why the Earth must be protected. Plant trees. Make intentional decisions with lifestyle (mode of travel, living arrangements, diet) that lower carbon emissions, and explain these things to your children starting at a young age.
Because the world will NEED people with those values in the future if climate change will ever be addressed and eventually reversed without a collapse of human civilization. Because if everyone with a positive view of the environment and the need to fight climate change does not pass on that worldview to their children, BUT those who deny climate change and do not value the environment pass on their worldview to their children, then that is clearly not going to work out for those who value the environment.
Just to follow up, there are things one can do immediately to drive their carbon emissions negative.
For instance, pay people to plant (native) trees and restore ecosystems (or do it yourself). About $15/month could offset your entire carbon footprint and bring it negative: https://mossy.earth/
If you don't buy that argument for forest restoration counting ($15/ton of CO2), then you could also try some of the more expensive methods like sustainable biochar sequestration ($300/ton CO2). Even the super expensive options for offsetting CO2 are no more than a car lease payment at the individual level (and cheaper, of course, if you reduce your direct emissions as well).
It is not realistic to expect that children will live without carbon emissions when it is clear that billions and billions of people don´t do that.
We have too many people on the planet. Carbon emissions is only one of the many huge environmental problems we have. Creating new consumers to the planet is clearly the most devastating act for the environment what individual people can do.
You can't just dismiss out of hand the power of individual choices (living carbon negative) while simultaneously advocating for a certain type of individual choice (not having children).
The number of people that can inhabit the planet without destroying the environment is highly dependent on individual choices and (maybe even more) government policy. Government policy is determined by voting power, which is in turn determined by the values of people weighted by population. So absolutely it matters if the pro-environment folk advocate removing (to some degree) their own voice from future populations of voters while anti-environment folk do not.
The most devastating act that individual people can do is to not pass on positive, lasting values to the next generation. Because you're not going to stop anti-environment people from passing down negative values by doing so; you'll in fact be amplifying their stance. We must heal the Earth.
I'm pretty sure that by "the world" the GP meant human civilization.
And I feel like that's obvious enough that this objection that you and others raise has to be willful, disingenuous misinterpretation, just to be disagreeable or something.
When people implicitly say that bringing children in the world is necessarily a net-negative on climate, they're implying that their lifestyle is necessarily net-carbon-positive and that they just refuse to do enough to make their own lifestyle net-carbon-negative. Yet it IS possible to do so. I'm reminded of this Indian fellow who planted an entire forest pretty much by himself (although surely his wife/family also helped enable him to accomplish that goal): https://www.youtube.com/watch?v=i7i3QlMvsZs
...there are so many decisions one can make to cut one's carbon emissions to near zero. And some decisions can even make one's carbon emissions negative (some startups at Y Combinator, even... although there are more proven methods as well).
The most powerful thing as a parent is that you can help pass on your values to your children. Teach them (through example) how to live a low or negative carbon lifestyle and teach them the value of the environment and why the Earth must be protected. Plant trees. Make intentional decisions with lifestyle (mode of travel, living arrangements, diet) that lower carbon emissions, and explain these things to your children starting at a young age.
Because the world will NEED people with those values in the future if climate change will ever be addressed and eventually reversed without a collapse of human civilization. Because if everyone with a positive view of the environment and the need to fight climate change does not pass on that worldview to their children, BUT those who deny climate change and do not value the environment pass on their worldview to their children, then that is clearly not going to work out for those who value the environment.