There is no real "inevitable" with climate change. More CO2 in the atmosphere will cause higher temperatures. There may be a "tipping point" where a little more CO2 will cause the system to shift dramatically to a higher temperature. But we sure don't know where that is. To give up trying to do anything about climate change (lower emissions, geoengineering, etc.) because it is inevitable we will have 2 degrees of temperature rise no matter what, is to loose track of the fact that 2 degrees would be much better 5 degrees which is much better than 10 degrees.