Although I didn’t really think through starting this blog, one motivation was that I was aware that quite a lot of what was said about climate science in the blogosphere was simply wrong. I thought that if I could point out these basic errors, people might go “oh, okay, I didn’t realise. Thanks.” Of course that isn’t what happened and I was, obviously, naive to think it would.
In one of my early posts, I pointed out what I thought was an error in a Watts Up With That post written by Roger Pielke Sr. Tom Curtis, very kindly 🙂 , came along and pointed out that I was actually wrong. So, I wrote another post in which I acknowledged my error and ended up in a lengthy discussion with Roger Pielke Sr about feedbacks. I thought his conclusion about whether or not they were already operating was wrong. We didn’t achieve much, but it was perfectly cordial; something I value quite highly these days.
I haven’t really encountered Roger Pielke Sr much since then, but in the last couple of days have been engaged in a discussion with him on a RealClimate post. The discussion relates to his guest post on Judith Curry’s blog in which he suggests an alternative metric to assess global warming, which I’ve discussed before. The basic idea is to assess global warming using the following equation
This is essentially the energy budget formalism, and is a perfectly reasonable way to assess global warming (with some caveats). The problem, though, is that I think Roger’s definition – and understanding – of the terms isn’t quite correct.
The equation is basically saying that if one considers some time interval over which there is a change in external forcing, , and a change in temperature, , then if the climate sensitivity is , there will be a change in system heat uptake rate (or change in radiative imbalance) of . Roger, however, interprets as simply being the radiative imbalance, rather than the change in radiative imbalance. This is only true if the initial state is one in which the system is in equilibrium and hence the initial system heat uptake rate (radiative imbalance) is zero.
Additionally, Roger doesn’t appear to understand the definition of a radiative forcing. For example, in this comment he asks
What is the current (2014) radiative forcing from added CO2 concentrations (above the pre-industrial concentrations)? We do not need the difference between these two time periods, which the IPCC presents, but the current forcing given that some of the added CO2 has been adjusted to by the warming up to this time.
Now, I don’t think this actually makes sense. A radiative forcing is defined as being
the change in net (down minus up) irradiance (solar plus longwave; in W m–2) at the tropopause after allowing for stratospheric temperatures to readjust to radiative equilibrium, but with surface and tropospheric temperatures and state held fixed at the unperturbed values.
In other words, if there is some change in an external driver of climate change (Sun, volcanoes, anthropogenic GHGs), how does this change influence the net irradiance, or the net flux into the system, without the troposphere responding to this change. You can’t really define an instantaneous radiative forcing. You can define a total, or a change. Also the statement the current forcing given that some of the added CO2 has been adjusted to by the warming up to this time is similarly confused, since as the system adjusts, the radiative forcing doesn’t change. The net flux changes due to the Planck response and other feedbacks, but the forcing remains the same. I’ll also add that this comment is suggesting that Roger Pielke Sr also doesn’t understand the origin of some of the data that he’s using in his analysis.
So, this seems to be an example of someone who is critical both of mainstream climate science and of the IPCC, but doesn’t appear to understand some of the basic concepts that he’s ultimately criticising. I have a similar issue sometimes with Judith Curry who often criticises climate scientists (or the IPCC) for not considering natural warming processes, when in fact they do. The reason that it appears that they don’t consider these processes is really because these processes appear unable to explain our recent warming. It’s not that they’re being ignored, it’s that they seem to be much smaller than the anthropogenic influences. There’s nothing wrong with trying to understand the role of natural processes, but it would be good if those doing so (and who thought they might have a significant influence) appeared to understand why many think they’re not a significant driver of our current warming.
In a sense, this is why I sometimes find the whole idea of an improved dialogue difficult to contemplate. I’m all for improved dialogue but am not sure I see the point when the most suitable response to what someone says is “apart from being completely wrong, that’s an excellent point.” Now, of course, it would be great if – when pointing out these errors – the response was “oh, okay, I didn’t realise. Thanks.”. However – as I pointed out at the beginning of this post – I’d be naive to think that that was likely. Of course, if I’ve made some error (and I may well have) feel free to point them out. If you do, and if you’re right, I promise to respond with “oh, okay, I didn’t realise. Thanks.” 🙂