Actually, burning of trees helped reduce CO2 over the long term. That's because burning is incomplete and produces charcoal. Charcoal doesn't decay, so when it is buried it semi-permanently takes carbon out of the biosphere. Over time, this would draw down atmospheric CO2. Some coal deposits from that period have a significant fraction of charcoal in them.

IIRC, that's lignite coal?

I don't think so? The charcoal would remain identifiable as the coal is matured by burial and heating (perhaps not all the way to anthracite).

Ah true. It'd be more of a structural thing I guess.

This doesn’t sound right. Iirc there have been many periods in earth’s history warmer than today, and carbon was part of the climate feedback for all of them, but this is the first time that warming is coming from direct forcing via co2.

This is definitely not the first time temperatures have risen due to direct co2 levels. Last time was only about 3 million years ago.

Are you sure? Because my understanding is, in the past what has happened is that some other force causes a bit of warming, and then the oceans heat up, which causes co2 to bubble out, which then causes more warming, which causes more co2 to bubble out, and so on. So co2 is an active part of the picture but it wasn’t the independent variable, so to speak. Whereas now we’re mining fossil carbon and squirting it directly into the atmosphere, which is new.

And climate scientists are very smart and have worked out how much the added co2 amplified the original warming, and have been able to work out how much warming you would get by doubling co2 levels, which appears to be around 3 degrees C.

It’s very similar. We’re just the ‘other force’ that is kicking it off this time, and we’re a bit more efficient than most.

Hmm, I don’t think you read what I wrote very carefully. I’m making a very specific and rather technical point about the feedback loops in the climate.

Basically the amount of co2 that the ocean can have dissolved in it is a function of temperature and the relative co2 concentration of the air. When the temperature of the water increases it can hold less co2. Just like when soda gets warm and isn’t pressurized, it gets flat.

Yes, that is part of the (theorized) feedback loop that has happened many times.

What is your point exactly?

Because you wrote "This is definitely not the first time temperatures have risen due to direct co2 levels. "

Strictly speaking that's not true. Listen man I don't really want to hold your hand and walk you through this.

It is definitely not the first time temperatures have risen due to direct co2 levels.

Maybe you should actually read some of those studies?

[https://royalsocietypublishing.org/doi/10.1098/rsta.2013.009...]

Some of the recent ones (< 1 million years), co2 seems likely to be a feedback, not a forcing method - but there have been many times in the past where that is not a plausible explanation at all, with levels in the 2000 ppm range.