You're saying that you care about the impact the planet has on you, not vice versa. It's time to recognise that 'harm to the Earth' isn't abstract and you (and your grandchildren) are co-dependant upon the Earth for your survival.
No, the GP is saying that humans evolved on the Earth, and changing the Earth on short timescales will affect his offspring who cannot evolve quickly enough. I personally feel the same way.
I really do not care what particular composition of gasses surround whatever rock that my offspring live on, nor the temperature of those gasses. I'm just concerned that the composition of gasses and their temperature are suitable for my offspring to live and grow food in.