Climate change is an evolutionary phenomenon, it has been occurring for billions of years ,will continue to happen for billions of more years, regardless if humans are present or not. Some of you worship the scientific community as if they are some kind of God when in fact they are only trying to explain the course of natural events, well at least some, others, well there are nut cases everywhere.
During the Pliocene about 3.5 million years ago, the entire world's thermohaline circulation changed because North and South America collided. The Earth was already cooling and getting drier. Glaciers started forming on Greenland like they did in the past over Antarctic, which had a circumpolar current deveop after South America, Austraila and India leave the area around 50 million years ago. What I'm talking about in the Pliocene was the Isthmus of Panama connecting North and South America, stopping a mostly circum-equitoral current that existed for around 150 million years, since the Cretaceous. It essentially made our modern world and Gulf Steam, so our world was drastically changed.
Other major things were happened too, like Africa isolated the Mediterranean Sea causing it to dry up and the arctic ice cap appeared.
When major changes are happening to a planet, how can we measure the sensitivity of a planet to changes, based on it's past, when they are totally different planets? It doesn't make a difference if the past world has changed, because we are talking about us changing our present world and a world can change quicker than we are smart enough to figure it out.
I believe once the modern Gulf Steam was created and with present CO2 levels, our planet became sensitive to Milankovich Cycles, when it wasn't that sensitive before, so any model that doesn't take exact thermohaline circulation into account is meaningless and it's hard to even know what the thermohaline circulation of a past world was. CO2 was declining with the Himalayas removing it, so eventually with a world having a large isolated mass of land at one pole and a nearly isolated ocean at the other, the Atlantic cooling during it's isolation because it could get more warm water from the tropics, there was a major shift, but the oceans buffered it until now and now means humans building cities, doing business and speading since the Plioncene (talk about a run on sentence).
I only know what I know when it comes to the world and I have tried to study the facts, but just like any scientists, I don't want to go out on a limb and look like a fool.
My personal opinion is this world will change faster than these scientists say it will, so I just contadicted myself and what else is new. The problem I've had in life, is I'm right nearly all the time and it must be that Cherokee blood.