Winds along with the earth's rotation causes currents. Ice Age- dramatic shift in climate thought to be responsible for the impoverished European flora and fauna. Over the past 100M years earth has cooled, and see an increase in both temperate and boreal climatic zones on earth. In past, most CO 2 in atmosphere from terrestrial organisms, usually balanced by photosynthesis.
Different models use different values.
Where physical barriers to dispersal prevent distribution of species from following shifts in climate belts, local populations may become extinct, being replaced by others that are better suited. Will see change in agricultural belts, areas covered by forests. Much of southern Florida under water. But not all animals are capable of moving as far as necessary.