It is difficult to form conjectures about timelines that are so long -- up to 100 years.
I don't think we know what will happen for sure. Some animals may do better and some may do worse, but overall I think such a rapid change in environment will make it difficult for most species to adapt or migrate.
I think the human suffering will mostly be due to migration and hunger. I don't know how this compares to historical global catastrophes like the plague or genocides caused by global colonialism. The shear size of today's human population will increase the numbers of individuals who suffer, I think.
I think a lot of the human suffering will be due to scarcity of resources to sustain the human population. So, I think if we started now encouraging people to not bred so much and actively tried to reduce the global population in advance of the catastrophe it would minimize the suffering.
Frankly, I don't see why anyone would want to bring a new life into this world under current conditions; to see their own children suffer like that.
