maybe, maybe not. methane is a much stronger greenhouse gas. So if you reduced CO2 90%, but methane went up by 2X then you would have stronger warming. My point is CO2 is not the only greenhouse gas.

Methane is unstable which is why you can burn it. Thus, we have an automatic and endless Methane sink.

You mean "If you reduce CO2 production by 90% by humans"

The analysis that I'm waiting to see is "of the global CO2 production each year, how much of it is due to humans?"

If we contribute 90% of CO2 production, then reducing it may change things.

If we contribute 10% of CO2 production, then even reducing our portion to zero, the overall change is near-negligible.

If my bath is overflowing, the only water I have to worry about is the relatively small volume coming over the edge - not the total amount of water in the bath.

The ecosystem produces vast amounts of CO2 ... and consumes a similarly vast amount. It is the imbalance that you need to worry about. And that imbalance is largely caused by humans either damaging CO2 sinks or releasing CO2 that ha been sequestered over the last few billion years

To continue your analogy: if the goal is to stop the overflow, then we should probably see what the contributors are.

If the faucet is on and your kid is dropping pennies in, both are contributing to the overflow but stopping your kid is going to be irrelevant.

Do we know which humans are?

The point is that the faucet, in this analogy, is not contributing to the overflow. The natural inflow from the faucet is matched by a natural outflow from the drain. The surplus is the problem, not the absolute inflow.

Of course, turning down the faucet would still help. But in this analogy, the faucet is jammed on, but the kid might stop if you ask him the right way.

So your assertion is that the planet is a perfectly steady state, static system?

Almost. Right now, the drain is actually emptying the tub faster than the faucet is filling it. Atmospheric CO2 is increasing at a lower rate than CO2 is being released by humans, because natural sinks are absorbing a lot of it. It was fairly stable, on human timescales, before we started adding our own input.

Can you substantiate your thesis a bit? I.e. explain where the CO2 that the nature is (allegedly) producing is coming from?

For humans, it's pretty simple: we're burning the oil on the timescale of centuries that the nature has been storing on the timescale of billions of years. For nature, the longest CO2 cycle is at most a multiple of the longest life-span (~500 years), and there's no indication that the cycle has changed (i.e. that suddenly more trees are burning in natural fires than have for the past few millenia).

According to the EPA:

"While CO2 emissions come from a variety of natural sources, human-related emissions are responsible for the increase that has occurred in the atmosphere since the industrial revolution."

Ref: https://www.epa.gov/ghgemissions/overview-greenhouse-gases (on the carbon dioxide tab)

And the Energy Information Association goes on to include magnitudes here:

http://www.eia.gov/oiaf/1605/archive/gg04rpt/pdf/tbl3.pdf

If those numbers are accurate, humans contribute 0.2% of CO2 and 60% of methane. So my follow up is: Which gas is a worse contributor? Because we can greatly influence one of those.

But "source" of CO2 is meaningless without the other column, "absorbtion". Obviously nature produces CO2 (e.g. by animals and plants breathing), and CO2 isn't a problem by itself. The problem is the increase of CO2, i.e. the delta between production and absorbtion. That 0.2% of human CO2 surplus turns into 20% increase over a 100 years. That's the problem, not the production/absorbtion/cycling of CO2 itself. And that part, AFAIK, is all human-made!

Based on your statements, is there anyone whose data and interpretation of it you'd trust? I feel pretty confident that you've already ruled out anyone respected within the scientific community, particularly anyone studying climate change.

It's a lot like saying "prove it to me with numbers, because all the numbers you're giving me are bunk."

Edit: tense

I'd love to see simple magnitudes:

"Nature generates X million tons of CO2 each year. Humans generate Y million tons of CO2 each year which primarily comes from A, B, and C."

From my own search, there are lots of numbers around X and Y and they're wildly different. Do they converge around a range?

Suppose net CO2 went up on average by 1ppm per thousand years by natural causes. Well, over the last 2 billion years 2,000,000,000 / 1,000 * 1= 1,000,000 ppm. 2,000,000 ppm wait part per million so 2 parts per part that's meaningless.

Thus, net CO2 from natural causes must average very close to 0 on long time scales.

PS: If you look into it natural carbon sequestration increases slightly as atmospheric CO2 increase which is why things end up in balance. Natural carbon sequestration is also why there are huge sources of coal and oil to begin with.

You can also come at it from the other direction: look at how much CO2 humans have released over the past century or so, look at how much more CO2 is in the atmosphere, and compare. I looked this up a while ago and as I recall the result was that about half of humanity's CO2 production was being absorbed somewhere, and about half of it is still around and accounts for the increase in atmospheric CO2.

Which is to say, the natural net contribution to CO2 in the atmosphere is negative. If we somehow put a stop to natural processes involving CO2 and just carried on with human activity, the rate of CO2 accumulation would go way up.

> Which is to say, the natural net contribution to CO2 in the atmosphere is negative

What?

Looking at the last hundred years or so, natural CO2 production is less than natural CO2 absorption. The difference is substantially less than artificial CO2 production, so the net change is still positive.

Do you have a link with the figures?

There's a summary here:

https://www.co2.earth/global-co2-emissions

This is the relevant bit for how much emitted CO2 has accumulated in the atmosphere:

"From 1870 to 2014, cumulative carbon emissions totaled about 545 GtC. Emissions were partitioned among the atmosphere (approx. 230 GtC or 42%), ocean (approx. 155 GtC or 28%) and the land (approx. 160 GtC or 29%)."

If you want to double-check against increasing CO2 concentration, the mass of the entire atmosphere is about 5.15e18 kilograms, so one part per million is about 5e12kg or 5 gigatonnes.

The preindustrial CO2 concentration was roughly 280ppm. We're now at about 400ppm, so that's 120ppm or about 640 gigatonnes more CO2 in the atmosphere today. Things are a bit confusing here because for some reason emissions are measured in gigatonnes of carbon alone, not CO2, so you need to multiply emissions by 3.67 (the mass ratio of CO2 to just C) to get CO2. Taking the cited 230 GtC added to the atmosphere and multiplying by 3.67 gets us 873.46 gigatonnes, which is roughly in the same ballpark, considering this is an off the cuff internet comment using random googled sources.

Thanks

It's not negligible, because the balance of the process matters. The natural processes producing CO2 were in balance with the natural processes removing it from the atmosphere, and now they're not. So the overall proportion in the atmosphere is increasing.