Earth will live on... it's never been about the planet, it's about Humans, and other creatures. Mass extinction of even something as small and insignificant as mosquitos would have a dramatic impact on the ecosystem and food chain. Those lesser creatures are not nearly as resilient as humans.
Additionally, when, in the last 4.54 billion years of the earth, were humans burning hundreds of thousands of tons of fosil fuels and increasing the CO2 concentration in the atmosphere? Concurrently during this time, volcanic eruptions have also continued to spew the same greenhouses gases in the same way they have previously. How are we helping the earth do the activities to start to revert back to the place it was before the CO2 emissions? How can something bounce back, if we never stop pulling?
Just because it can deal with the increases and decreases due to natural eb and flow, how does that justify the increased amount over the recent short term? It's like saying that if you can do 5 lines of coke in a night, you're gonna be fine doing 500.