A thought experiment

To follow up on my – possibly poorly titled – post from a couple of days ago, I thought I would pose a thought experiment. This is entirely unrealistic and is just intended to, maybe, illustrate what I was trying to get at in the earlier post. Of course, it may fail dismally, or may just be too unrealistic to make any sense, but I’ll give it a try.

Consider the following scenario. We start with the planet in energy balance and then we emit, in a short space of time, a large amount of CO₂ that increases atmospheric CO₂ concentrations. Afterwards, we fix our emissions to maintain, but not increase, this higher atmospheric CO₂ concentration. This increase will produce a change in anthropogenic forcing. Consider also that at the same time the Solar forcing increases by an amount greater than the increase in anthropogenic forcing. Given these two increases in external forcing, we will warm and – one might argue – that we will be mostly warming because of the change in solar forcing.

Now imagine that at some point in the future, the Solar forcing drops back down to what it was at the beginning, so that there is now no net change in solar forcing. Also, imagine that this happens at a time when the increase in temperature exactly compensates for the increase in anthropogenic forcing (and associated feedbacks), so that the system is again in energy balance.

So, we have a situation where the only change in forcing is anthropogenic and in which the system has warmed so as to retain energy balance. Is the warming :

1. Mostly – or all – natural.
2. Mostly – or all – anthropogenic.
3. Both natural and anthropogenic.
4. Neither.
5. It’s just too complex to really describe in such a simple way.
6. Stop writing posts that don’t make any sense and just confuse everyone.

Okay, there’s my thought experiment. Remember, it’s not meant to be realistic and is just an attempt to maybe illustrate what I was trying to get at in my earlier post. It may not succeed in doing so and – just to avoid confusion – I’m really not trying to argue that changes in solar forcing can’t warm us (i.e., if you think that the point I’m trying to make is that there is no such thing as natural warming, you’d be wrong).