The minor changes aren't important in their own right. The problem is if we hit a tipping point. Which we are likely to be close to. Because that's a one way trip to extinction. The planet will be fine, it doesn't worry about temperature fluctuations, but there will be no more humans
It's not going to cause humanity to go extinct. Don't be absurd.
It will cause massive problems including rising sea levels and famine but humanity will not go extinct over it.