There are probably a lot of factors. Pumping gigatons/year (literally) of previously geologically sequestered carbon into the atmosphere for a century+ is bound to have some effect. Removing sinks and reversing previous reservoirs also is going to have impacts. No question.
I wouldn’t discount measurable increases in global atmospheric co2 either way. And continuing to pump gigatons/yr of ‘new’ co2 into the atmosphere is so unlikely to help the situation, that I’d hesitate to try to downplay it.
The issue with wetlands and forests in this math is that both, generally, are like ‘capacitors’ - except in rare cases, their storage is temporary. It doesn’t (and can’t, if you do the math on volume of space available!) store large quantities of carbon permanently on a geological timeframe. Unless said wetland or forest gets subducted or buried anyway before it rots. If that’s happened though, it drying up isn’t likely to reverse that sequestration.
OPEC currently estimates approximately 70 million barrels of oil are extracted each year (coal far more I believe by volume). Each barrel is 42 gallons. That is just a hair under 3 billion gallons of oil alone. Or 11.3 million cubic meters of oil, per year. Nothing in comparison to the large rivers of the world, but enough to drown most any large city.
It would take a lot of lost wetland by volume to make up for that, especially when you look at cumulative effects over time. Even if the wetlands were pure carbon by volume (hydrocarbons aren’t, but are quite close for a dense liquid!), it isn’t clear there even is or has been that much wetland. That may give you a start though, for the math.
Your comment - ‘“the industrial revolution" is not really the primary cause of human caused climate change but perhaps largely coincidental’ reads to me like downplaying it?
I added some math to my comment, hopefully it helps.
One way to estimate might be a simplistic, volume/density one. How much carbon is there in the applicable geography/land column? In a forest, it would be the trees themselves (above ground) + the soil. In a wetland, the vegetation + mud/sediment.
There should studies with core samples + samples of vegetation that can give good estimates. Then extrapolate. And you’ll have at least a rough estimate of the potential upper and lower bounds, assuming all that carbon instantly turned atmospheric (or at some assumed rate).
Combine that with numbers like I gave above (I’d do some googling for Coal numbers and add that too), and you should be able to estimate the maximum relative contribution of each source. We’re burning Coal in the billions of tons/yr quantities, and each short ton of coal produces well over a ton of co2 - so that is billions of tons/yr of co2 on its own.
Peatlands cover just 3 percent of the planet’s surface but they store about 30 percent of all land-based carbon, or twice as much as all of the world’s forests combined. Coastal wetlands remove atmospheric CO2 up to fifty-five times faster than rain forests.
I'm not downplaying anything. I'm just seeing data that suggests wetlands loss is a really big deal.
I wouldn’t discount measurable increases in global atmospheric co2 either way. And continuing to pump gigatons/yr of ‘new’ co2 into the atmosphere is so unlikely to help the situation, that I’d hesitate to try to downplay it.
The issue with wetlands and forests in this math is that both, generally, are like ‘capacitors’ - except in rare cases, their storage is temporary. It doesn’t (and can’t, if you do the math on volume of space available!) store large quantities of carbon permanently on a geological timeframe. Unless said wetland or forest gets subducted or buried anyway before it rots. If that’s happened though, it drying up isn’t likely to reverse that sequestration.
OPEC currently estimates approximately 70 million barrels of oil are extracted each year (coal far more I believe by volume). Each barrel is 42 gallons. That is just a hair under 3 billion gallons of oil alone. Or 11.3 million cubic meters of oil, per year. Nothing in comparison to the large rivers of the world, but enough to drown most any large city.
It would take a lot of lost wetland by volume to make up for that, especially when you look at cumulative effects over time. Even if the wetlands were pure carbon by volume (hydrocarbons aren’t, but are quite close for a dense liquid!), it isn’t clear there even is or has been that much wetland. That may give you a start though, for the math.