Our scales of interest are also broad. In the time domain, while recognizing that important
interactions between social and environmental systems occur at all scales, we have found it most
helpful to focus on what might be called “grandchildren” time: periods of more than years but
less than centuries. Because ideas and policies, and the structure of social organizations and
technologies of the present cast a significant shadow on the future, we adopt a dynamic view,
emphasizing not some distant goal of achieving sustainable development, but rather on
contemporary progress (or lack thereof) along a transition toward sustainability.
Clark, B., Bong, aarts, J., Carpenter, S., Dasgupta, P., Kates, B., Ostrom, E., ...& Levin, S. (2010). Sustainable development and sustainability science. Toward a Science of Sustainability.
I’m none the wiser for reading that – especially since that’s not even the same expression. I would expect “grandson time” to mean time spent with one’s grandson (like “me time” being time spent on your own). But presumably it has some other meaning in this context.
I think in this context it probably means the period of time in which a person's grandchildren will live their lives. The same time period we're referring to indirectly when we say things like "leave a better world for our grandchildren."
It might be called "grandchildren time" so apparently they've just come up with the term.
Most ordinary adult people tend to be intensely concerned about living conditions for their own ancestors and descendants for two generations into the past and two generations into the future. More distant generations are not generally much of a pressing concern, since they are either several years dead or not yet born.