ecosystems around them consist of a chaotic jumble of species, each of which (except in cases of monospecific specialization) has a different geological range corresponding to different ranges of adaptations and tolerances, that have come to assemble together only very recently, and whose function is far more a result of chaotic war, competition and depredation than any sort of planned order. Instead, the model of ecology we teach kids is an unrealistic fantasy of order, planning and cooperation, the balance of which we humans can destroy forever simply by breathing on it (leave no trace). We should teach them that any concept of "pristine" ecosystem anywhere outside of Africa is absolutely absurd considering the fact that most native megafauna went extinct 10,000 years ago (in North America's case as elsewhere, almost certainly due in part to overhunting by "ecologically conscious" paleo-Native Americans) Whether or not human emissions are about to cause a massive switch in climate is more or less irrelevant in the big picture. It will almost certainly happen anyway, no matter what we do, and it has happened already, millions and millions of times. The only way to avoid it is to achieve a level of science that can engineer and control the climate of Earth (which is essentially what we are trying to do by cutting down carbon emissions) And if you argue that all modern species are adapted to Pleistocene glacial cycles, then logically, to stop the cycles will also be to upset the supposed plans