All that freed, formerly captured carbon comes from trees and plankton. How could burning it all lead to life-destroying conditions when life must have been able to exist under those conditions?
"all that kenetic energy released when jumping off a building was formerly potential energy stored when walking up the stairs. How can that lead to life destroying conditions when life previously held that energy?"
The rapid change in environments can make many species no longer suitable for their environment leading to extinction. Sometimes they can transfer to a new environment, or sustain at a degraded efficiency, but often they cannot if the environment change is drastic enough. This is happening everywhere all at once.
People aren’t going to destroy all life on earth via climate change because humans are going to be dead in conditions that many life forms would happily survive in. Having said that, evolution operates on geologic timescales 100 years isn’t nearly enough time for most species to adapt to significantly different conditions. Florida alligators might happily expand their range further north in response to climate change, but that’s different.
As to the larger point, the sun was ~30% dimmer 4.5 billion years ago and will get about 67% brighter over the next 4.7 billion years. While we would be dead long before we could free up all the worlds trapped carbon, in such a hypothetical situation the world isn’t simply returning to an earlier state.
Some people argue that co2 levels were higher in the past. Yeah but the sun was a few degrees cooler. You simply needed more co2 to reach similar temperatures.
Energy on Earth isn't conserved, as it's not an isolated system - the Sun is constantly adding energy to the Earth, and we are constantly radiating energy out into space as well. Coal and oil were basically batteries filled with solar energy from millions of years ago. We are now discharging those batteries, adding back all of the solar energy captured over millions of years to the Earth today, in addition to all of the energy the Sun is still adding at more or less the same rate.
It's the same principle as what makes a battery fire so destructive - all of the energy stored in the battery in a plant somewhere else suddenly gets discharged all at once in your car.
Every night temperatures drop much more than the temperature increases from the hydrocarbon consumption. Are you sure that the energy of the hydrocarbons is the problem and not the greenhouse effect?
Things could get very bad, but it also turns out that plankton and plate tectonics have locked carbon/energy far away from our reach. It's a very slight glimmer of hope.
The rapid change in environments can make many species no longer suitable for their environment leading to extinction. Sometimes they can transfer to a new environment, or sustain at a degraded efficiency, but often they cannot if the environment change is drastic enough. This is happening everywhere all at once.