Reading between your lines, I guess you think that the IPCC AR5 projections are the best possible so any other view is an "unlikely possibility". Is that correct?
Do you agree with the UK Met Office summary? Cumulative emissions from pre-industrial (1750-2012) have reached 590 ±75 GtC. This is an update to the IPCC 1750-2011 estimate of 555 [470 - 640] GtC as 2012 emissions are included and an upwards revision is made of early 20th century land use emissions (20 GtC). The IPCC estimates that with cumulative emissions of 1000 GtC, there is a two-thirds chance of staying below 2°C relative to pre-industrial. At current levels we are over half way towards this figure. If other non-CO2 gases are included the emissions budget reduces to 790 GtC.
http://www.metoffice.gov.uk/research/news/gcb-2013
I don't think this is right and I am sceptical of their implication that 2 deg C is safe.
I think there is some conservatism by scientists, but when AR5 is stated with 'high confidence' then you will only find a few suitably knowledgeable people who disagree.
I think it is quite a stretch to say this means AR5 projections are the best possible. There is always room for lots of improvement. Also there have been measurements, papers etc since AR5.
Generally I feel the scientists deserve a fair bit of respect. They know a lot more than me and I don't think they deserve a lot of the criticism they are getting from some around here. Of course others here may know enough to be in a position to criticise fairly.
>Do I agree?
Who am I argue? When AR5 is stated with high confidence, I trust that view. The quote seems an update since AR5 so obviously AR5 is out of date and we are nearer to danger now as a result of the update.
The quote simply states the science of this carbon budget leads to warming of X. Therefore I don't need to consider what is dangerous to agree with this quote. I do have to have considered whether I trust the modelling process, and I do.
It is, I think, politicians that defined dangerous as meaning 2C above pre-industrial.
> sceptical of their implication that 2 deg C is safe.
I think I would also dispute the characterisation '2 deg C is safe'. To me, saying over 2C is dangerous can easily imply that under 0.5C is relatively safe and 0.5C to 2C is unclear but has increasing chance of being dangerous.
We have nowhere near the knowledge to say x.y is safe and the next number x.z is dangerous. For all I know, there could be a small chance that 3C is not dangerous or there could be a small chance that 0.3C above pre-industrial is dangerous or maybe both.
The politicians seem to have gone for using dangerous and over 2C interchangeably. What should be considered dangerous probably depends upon the position you are in. At some point doing anything other than the maximum possible becomes dangerous. That is a very late point of danger. Should dangerous be a moving target, starting well before that point and moving towards it as we get closer to danger?
Problem with a moving target might be that we are always 10 years away from burning the remainder of the carbon budget. To infer from that we can carry on burning carbon would be pretty silly but it would encourage a pov that these environmentalists are always crying wolf.