In the documentary “Before the flood” there was this scene in which Leonardo DiCaprio was in a conversation with Jason Box on a glacier in Greenland. This came after a scene of Leonardo DiCaprio in his earlier days when he still was thinking that global warming could be solved with small individual actions, like changing light bulbs. Then an ominous sounding voice-over:
But it is pretty clear that we are way beyond that point right now. Things are taken a massive turn for the worse.
Cue in a calving glacier, followed by Jason Box saying:
“We keep finding things that aren’t in the climate models. They are used to project the future. So that tells me that the projections for the future are really conservative.”
That was interesting. I heard many times before that climate models are “too conservative”. I understood that the models were cautious and underestimated things, therefor it is expected that it would get worse than the models showed. That is also how I understood the statement from Jason Box. I am pretty sure that this statement was not being used as having some innocent meaning in this one-sided documentary, immediately after the statement that “things are taken a massive turn for the worse”…
Until now I didn’t understand the reason for this “conservative”-claim. Luckily, this time the reason is mentioned: many things are still being found that have to be put into the models. Okay, I could somehow understand this kind reasoning.
I have no problem agreeing that many things are not in the climate models yet and that scientists keep finding things that are not accounted for in the models. That is the consequence of the Earth, and its climate, being a complex, coupled and chaotic system. In such a system it is not unusual that some things are not accounted for.
But how could we then, in such a system, be sure that the projections for the future are “really conservative”? As far as I know it cuts both ways. We don’t know the things we don’t know. Maybe these will confirm the theory, maybe not.
If it is true that we keep finding things that aren’t in the climate models, then the conclusion would rather be that the projections for the future are not really reliable at this point, especially when it comes to policies. We can not assume a direction if we keep on finding things that are not accounted for.
From previous experiences I know that such claims about the performance of the models concerning the ice melt don’t mean much. The best example was the one in which was stated that the climate models were lagging far behind the (sea ice) observations, until reality finally caught up and the opposite was claimed. I expect that this “projections for the future are really conservative”-claim is also just the same hyperbole.