Please cite support for your claim that effects of surpassing these boundaries are linear.
The people who actually know the science in these areas do not agree with you. Specifically with regard to global warming, the science has been clear on this for decades now: past around 1.5C, we risk cascading effects that could be uncontrollable. This is really fairly common in natural systems: if you mess it up, past a certain boundary effects accelerate and are uncontrollable.
Science if pretty clear that if you build a house out of flammable materials with no regard for fire safety, it could burn down and kill everyone kill it.
What you are doing is the equivalent of complaining that your house didn’t burn down this month and therefore fire safety is fake science
Non-discreteness does not imply linearity. Seems like a nitpicky point to make, but in fact the difference between linearity and other types of continuous growth can easily be the difference between a non-issue and an unprecedented catastrophe.
The people who actually know the science in these areas do not agree with you. Specifically with regard to global warming, the science has been clear on this for decades now: past around 1.5C, we risk cascading effects that could be uncontrollable. This is really fairly common in natural systems: if you mess it up, past a certain boundary effects accelerate and are uncontrollable.