To take one example, it is easy to call for "saner" environmental policies, but to what degree can we be sure that the (real) harm caused to future generations by climate changes outweighs the (equally real and immediate) harm to those whose livelihoods are dependent on producing coal, oil, and natural gas, or to the massive costs needed to renovate the power grid, or to the extra expense of transportation to those struggling to get by as is? We cannot quantify the harm of inaction over the next century.
We can know it will be far greater, which ought to be enough.
Anyway, "the next century" isn't the relevant time frame. The effects of climate change will damage living conditions permanently.
