Fact 1: There is virtually perfect correlation between atmospheric CO2 and cumulative carbon emissions - so there is no measurable CO2 sequestration. Virtually all the carbon that has been burnt since the start of the industrial revolution is still in the ocean or the atmosphere. Even if we go to a zero carbon economy, CO2 levels will stay will stay sufficiently high to trigger dangerous climate change.
Fact 2: The recent rises in global average temperature can not be explained by the radiative forcing from rising CO2 emissions. The sharp temperature increases can only be due to increases in forcing from amplifying mechanisms such as methane and sea ice loss. So even if we could decrease atmospheric CO2 we will not be able to reduce heating.
Fact 3: Serious changes to the ecosystem were first observed in the early 1980s, namely coral bleaching, sea ice loss and methane releases of the Washington coast. At this time, global temperature increases were 0.5 deg C above pre-industrial baseline, so the safe temperature increase must be below 0.5 deg C and it cannot be the 1.5 deg C that COP is using as its target.
Conclusion 1: Solar Radiation Management (SRM) techniques are the only way of reducing temperatures in time, and should we delay , then the rise in temperatures will activate amplifying mechanisms to such an extent that SRM cooling will become overwhelmed.
Conclusion 2: SRM techniques will be have to be applied indefinitely and must be capable of being operated by future societies that are otherwise preoccupied with addressing the challenges of climate change.