[hotpotamus]

I wasn't aware of the Little Ice Age being much of a denier talking point. It actually does seem fairly relevant to this story since these sponges lived through that time period. But I'm mostly just looking at the XKCD temperature timeline https://xkcd.com/1732/

[defrost]

It waxes and wanes I'm sure, but I've seen far too much raising of the Medieval Warm Period and the The Little Ice Age as "Aha, Gotcha!"'s over the past three decades to push it down the list of denier "but what abouts".

They're valid subjects in their own right, to be sure, but rarely raised in public forums for the interesting details in context, mostly for the "<something> <something> AGW must be wrong! ('cause climate has changed before fossil fuel usage!)"

The actual variation was small in comparison to what we are seeing now and the effect more localised than truly global - it tends to be lobbed in as a hand grenade along with "what about higher C02 levels many hundreds of thousands of years ago".

"Ice Age" itself is another awful phrase for generating confusion - there are multiple meanings and usages, for some professionals we are still in an Ice Age as we still have glaciers (free, not polar, ice) and this Ice Age experiences advances and retreats of large glaciers .. sometimes almost to the equator, othertimes back to the mountaintops. For most people "Ice Age" is when ice covers the UK and when it doesn't it's not.

Back to these sponges:

The surface waters above these sponges absolutely saw a small decrease in mean tempretures during the Little Ice Age.

https://www.sciencedirect.com/science/article/abs/pii/S02727...

No argument there.

I freely admit I haven't read enough here nor dug into the details to find out whether these sponges that lived deeper than surface waters saw a small decrease in mean tempreture at that time or not.

Is that in the paper at all?

[hotpotamus]

I didn’t read the paper but did read the article and one of the cool aspects of it was that they did go back in the timeline to find known historical temperature anomalies after calibrating the sponges against a modern period with good temperature measurements, so I would assume so.

I just wonder if this actually does change the “baseline” Earth temperature as the article implies rather than just adds a bit more detail to known historical temperatures.

As far as the temperature variation thing and deniers, I’ve always thought Munroe did an excellent job with the visualization I linked above in showing why the current change is so unprecedented when compared with previous ones.