Ken,
I think you have the big picture roughly correct.
But, most of the rates for CO2 ins and outs are estimates based on some measurements and some assumptions. We don't currently have direct measurements for the total quantities for a lot of the processes, so we use modeling and adjust things so that the net result is the same in the model as in the actual air for
global average CO2 concentrations. So, there could be compensating errors in the modeling. The uncertainties in the models are mostly ignored by activists who are using results to support political agendas.
However, with new satellites, we are finally beginning to get some more comprehensive data on localized concentration variations, which can more easily be attributed to specific point and area sources and sinks.
So, the picture is being made clearer, and largely by space-based sensing.
But, forecasting the future is still not well in hand. Even though the UN has narrowed the predictions of temperature as a function of time, there is still a pretty wide range for even specific emissions scenarios. And, we do recognize that there is some non-linearity in the climatic responses, particularly in the initiation of the glaciation and thaw cycles.
With the current predictions that the Atlantic Meridional Overturning Circulation will soon shut down, and the predictions that will cause substantial cooling in the North Atlantic land areas, we are predicting changes, but not necessarily in the same direction as "warming". Knowing that the atmosphere has changed dozens of times from glaciation to thaw and back again over the last 3 million years, and not knowing that the details of how that occurs, we are still on somewhat shaky ground predicting the future out to a few thousand years from now, maybe even a few decades from now.
But, we do know that we are doing things that affect the parameters that are involved in the cycles. So, there is some rationale to minimize our impacts when we see them pushing the cycle in a direction that will cause us problems.
On the other hand, even the unperturbed cycle will cause us problems. Drastic cooling of the Northern Hemisphere, combined with decreasing sea levels, would cause us a lot of health and wealth problems, too. And that has occurred many times in the past 3 million years, apparently without any significant contributions from human activities.
Geological evidence shows us that the climate that we have enjoyed for the last few thousand years has not only been unusually stable, but that it has been in a condition that is representative of the unperturbed system for only about 10% of the time,
So, clearly, we need to be expecting this climate to change. We do not yet understand the system well enough to control it so that it will never change again. In fact, we don't yet really know if we have disrupted the cooling part of the cycle so that there will not be any more glaciation events. But, if we have, that might actually be to our benefit, overall - provided we don't send the climate into some sort of inferno.
But, with geological evidence telling us that the CO2 concentration has been as high as 1600 ppm tens of millions of years ago, and the temperatures being as high as 14 degrees C higher than now, it seems pretty clear that the Earth's climate is not headed for conditions like on Venus soon, with our current CO2 levels being around 400 ppm. (see
https://d26toa8f6ahusa.cloudfront.n.../Atmosphere-CO2-warmingStripes68-1536x742.jpg )
The biggest concern is that extremely rapid climate changes can stress species to extinction. And, this has happened naturally many times, apparently including to some species of human ancestors and their cousins, sometimes from cold instead of heat.
And, we are already causing mass extinctions by other means, mainly habitat loss, but also food hunting.
If we were still a sparse, roaming, hunter-gatherer species that could follow the desired climate conditions as they shift about, we would have less trouble adapting than our current situation allows, where groups are holding and fiercely defending specific areas against encroachments by other humans.
So, we are going to have to mostly adapt in place. We do have technology that no species before us has had. But, there is a question whether we can use it to our long-term advantage with the same degree of success as we have managed to use it for our short term advantage, with unexpected long term undesirable consequences.