Find it a little odd that climate models predict nothing to really happen absent a change in CO2 CH4 N2O levels. But I guess they are models and their parameters are set by people. Given the historical variances prior to 1750, and the fact we were in a little ice with low solar activity, would have expected some natural movement.

Obviously, there are other human impacts to take into account – chopping down forests, putting pollution into the atmosphere, and so on – all of which have some impact on weather and climate, so you have to consider more than just CO2.

With respect to 2ºC as a target, it was chosen as a nice round number below which we could cope with what warming brings. I’m pretty sceptical about a) the precise logic underlying that choice (it was essentially political – an EU proposed target now widely accepted), and b) its status as a “safe” target. As Bryan points out, many of the positive feedbacks are already happening, and have the potential to make coming under 2ºC difficult, if not impossible.

Gareth, question here, how did the IPCC / EU / scientists etc work out the default temperature to measure the temperature rise against?

(not trying to prove a point, accept the world has warmed, and accept that 0.7C sounds accurate, just interested to know the process for determining what the temperature ‘should’ be.

We are all going to focus on 2.0C above pre-industrial, but the fact is that things have changed, even on that short time scale since 1750AD, and the temperature then can not be held as what we should be at now. Is there any scientific thought into what we would be at now, without the increase in CO2 CH4 N2O?)

Thanks