I haven’t really had anything particular to say for the last day or so, so thought I would just write a post with a few thoughts. Having given the moderation issue some more thought, the main change I will be making is to insist on evidence if you want to introduce what might be a contentious topic. I don’t want to constrain the comment threads too much, but also don’t want them going of on random trajectories that are unlikely to be constructive. Hence, if you would like to make introduce such a topic into the discussion, you’re going to have to provide some pretty convincing evidence. As I mention in my updated Moderation page, some emails between a few individuals is not going to qualify as evidence that all of climate science is fundamentally dishonest. Also, Rachel has, very kindly, offered to help and so we may see some slightly more effective moderation in the future.
All such statistical analyses of the temperatures that have been done so far are fatally flawed…..
The flaws imply that there is no demonstrated observational evidence that global temperatures have significantly increased (i.e. increased more than would be expected from natural climatic variation alone).
This is, I believe, based on a parliamentary question, followed by a response from the UK Met Office. He seems to be arguing that statistical models cannot explain why the surface temperatures have varied as they have (which is kind of obvious) and therefore we can assume that they might not have varied as they have. I’ve covered this in an earlier post and Richard Telford has a very good post pointing out that statistics are not a substitute for physics (I really wish more would recognise this rather obvious point).
One other thing I was going to comment on was a recent post on The Hockey Schtick. The post is called a new paper demonstrates climates models don’t even have ‘basic physics’ of the greenhouse effect right. It refers to a paper by Russell et al. (2013) called Fast Atmosphere–ocean Model Runs with Large Changes in CO2. The paper’s abstract ends with
With CO2 at or below 1/8 of the 1950 value, runaway sea ice does occur as the planet cascades to a snowball Earth climate with fully ice covered oceans and global mean surface temperatures near –30oC.
The Hockey Schtick post comments that
However, -30oC is much colder than the -18oC calculated for an Earth with no atmosphere or oceans or greenhouse effect at all! Further, -30oC is much, much colder [i.e. 35oC colder] than the +5°C global mean temperature calculated using the IPCC formula for CO2 forcing using a CO2 level of 39 ppm.
To be honest, I was slightly confused about this myself until I realised: it’s a snowball earth so, presumably, the albedo would higher than it is today. It’s fairly straightforward to estimate the non-greenhouse temperature of a planet. The basic equations are
Most of the terms are fairly self-explanatory (if you’re uncertain about these equations and terms, feel free to ask and I’ll explain further), but A is the albedo, and a is the distance of the planet from the Sun. Currently A is about 0.3. If you solve for Tpl in the above equation using A = 0.3, you do indeed get Tpl = 255 K = -18oC. However, if the Earth has fully ice-covered oceans A would be considerably greater than 0.3. Using A = 0.5 gives Tpl = 235 K = -37oC. So, it’s not that surprising that the models with CO2 concentrations of 39 ppm had surface temperatures of about -30oC. One of the reasons I was wanting to write about this is that one of the paper’s authors, Chris Colose, posted a comment at the Hockey Schtick to point out that
You didn’t read our paper. The albedo in a Snowball is much higher than present-day, so temps can go go well below the modern effective temperature of 255 K. This is an elementary point.
So, does the author of the Hockey Schtick post quickly respond with what might be regarded as the obvious response : “Of course, how silly of me. I should have realised that. Thank you for commenting”? To find out, you could either read the HS comments, or you could simply take an educated guess. In this case, if you were to select what might – to many – be the obvious answer, you’d most likely be correct.