I wrote this on Tom Fuller's. I hope you appreciate it more than his crowd did:
Others may be accused of shifting goalposts, but I am innocent of the charge.
The ECS is probably between 2.5 and 3, where it has always been. The TCR is ill-defined, as it has always been. Global warming is not the key socially relevant metric of climate disruption, as I said before anyone was talking about the hiatus and as I still say now that the hiatus is apparently ending.
Changing the radiative properties of the atmosphere to a larger extent than the Milankovic forcing will cause substantial climate change.
The changed climate will almost certainly be substantially warmer, whence all the obsession on global mean surface temperature, which is after all relatively easy to measure. But the warmed global climate is not the cause of climate change – it is a consequence of climate change.
The main issue that people will have to deal with is not this global measure, but that this measure is the result of climate changing locally everywhere in ways that are hard to predict and hard to manage. The extent of change can already be expected to be comparable in magnitude to the Milakovic cycle changes but much faster, leaving local adaptations, both artificial and natural, stressed and at risk of decline. The longer we delay in reaching carbon neutrality, the larger the disruption we have committed to.
Nothing in the recent observational data calls any of this into question in the least.
The process is slow on political time scales. Talk about what will happen to GMST in 2017 is a fine example of missing the point. People may be silly enough that this will affect politics. But the climate system won’t care a bit.
The response of the climate system is dominated by how much fossil carbon gets emitted from the beginning of the industrial revolution until the day we reach carbon neutrality. The rest is secondary.