That number two. I was thinking that it was already covered. But again I am pretty certain the current climate models do not include the Milankovic cycles, tectonic plate movements, do not correctly predict volcanism and comet hits on the Earth.
I'm stunned. A reasonable response? *Applauds!*
Even if you're just yankin' my chain that is real progress!
So, we are in agreement: there are preexisting and unaccounted for dynamics of change in Earth (both climatic and most all the other "divisions" of the processes that comprise Earth). There are many distinct patterns in Earth's billions years long history, but we need not belabor that point.
The most important sum point: Earth's climate has always been subject to change, including radical change, rapid change, and "long" periods of stasis too. Since our first ape ancestor's arose during the Miocene Epoch some 23 million years ago the world has changed dramatically: mountains have LITERALLY come and gone, oceans have literally spread and ebbed, species most wondrous have come into existence and persisted, while countless others have gone extinct.
Certainly there some persistent themes, but on the whole change and variability have been the rule of thumb, and even restricting to the last 23 million years or so (the Ape Era) the magnitude of the swings of change have often been literally orders of magnitude larger than even the most controversial measures of climate during the last 100 years.
There are likely thousands, perhaps tens of thousands, of discrete "forces" that will eventually have to be accounted for to understand how, when, and why Earth's physiographic, geologic, hydrologic, biological and climatic systems have undergone the wild fluctuations it has undergone . . . well, that is more true for some of those classes of natural process than others.
Plate tectonics for example: 100 years ago the model was only being developed and it was not until the 1950s that the model received strong empirical validation. It is one of those wonderful models which has withstood the withering "attacks" of science, i.e., rigorous and concerted efforts to falsify the hypothesis, and which has come out of every examination stronger than when it went in. These sorts of models are actually the exception in science, not the rule as you and so many other seem to think. Many models wait for centuries to have their assumptions proven empirically or even to have their predictions validated by observation and efforts to falsify them foiled with supporting evidence.
Plate tectonics is probably one of the most successful models in the natural sciences, at least if we assess the term "success" in a holistic manner: how revolutionary was it at the time it was proprosed, how coherent and self-contained is the model, how rigorous is the model, i.e., does it rest on few unproven assumptions, does it generalize well and not require many context-specific caveats, have repeated efforts to falsify the hypothesis' predictions instead yielded effectively supportive evidence?
The mere joining of the isthmus of Panama between North and South America (which only happened some 12 to 15 million years ago) was a moment of such tremendous importance to Earth (and all the subdivisions of its workings which I outlined above) and yet the role which that watershed (LITERALLY!) played in Earth's climate and subsequent patterns in the cyclicity of Earth's climate has (as far as I know, which I admit may be a bit dated and uninformed) barely been considered.
The joining of two enormous continental land masses that effectively divide the planet east-to-east along nearly the full extent of longitude is an enormous Earth event, one of such magnitude that I doubt its occurrence is "regular." But there are others as well: https://en.wikipedia.org/wiki/Geologica ... nozoic_Era
You have acknowledge Milankovic cycles, but seem to be under the impressions that (a) those cycles are perfectly understood and the model is perfect for explaining past events, as well as (b) Milankovic cycles are the only "cycles" of interest. In fact, the solar system itself wobbles as it orbits the Milky Way, and the other celestial objects in the solar system and its extended neighborhood are also engaged in a complex dance wherein relative positions, alignments, orientations and encounters fluctuate rhythmically if not spasmodically.
All this to say: the state of Earth prior to humans large scale burning of fossil fuels and the growth of human populations (and our animal herds) beyond 1 billion is one that is best regarded as CHANGE. This applies to climate, physiography, biology, ecology, effectively the whole of the Earth system. There are literally innumerable "factors" at play, some of which are obvious as constant cyclic patterns, others which lurk at the boundaries of our detection capabilities may also be in constant cyclic patterns but with such long periodicities that may as well be "random" as far as any "models" we humans might come up with. And then of course there are factors which which effectively ARE random, like the joining of the Isthmus of Panama.
If we imagine the pattern of Earth's "climate change" over the past 23 million years or so as a "trajectory" that trajectory is not a unilinear one. It is arguably not even a spline pattern for the simple reason that: periods of regular cyclicity (which might be well-described by a single spline) are also punctuated for various reasons by periods of irregular cyclicity (which would require the introduction of one or more additional splines that are effectively INDEPENDENT of the pre-existing maths, and which may or may not exhibit recurrence). These matters are further complicated by the fact that, climate appears to be highly subject to feedback effects: a topic of sufficient scope that it is really best left for at least a separate post if not a separate thread.
Thus the pre-existing trajectory of Earth's climate from 23 million years ago to say 200 years ago is in fact, only very partly "explained" by existing models and existing observations, all of which leads to the point that: no one can say with any certainty whether a sudden dramatic rise in temperature (and assuming the observations we have do indeed support that clearly, which I remain somewhat skeptical about, though it seems many whose views I respect have come to acknowledge that it is probably there has been clear increase) is or is not an artifact of pre-existing climatic process.
Of course humans are having an impact on climate! We spew smoke, toxins, particulate matter, water vapor, various gases and myriad waste products into the environment. We cover enormous tracts of land in concrete and bitumen. We build billions of wooden, metal and concrete boxes and run machines to maintain constant environmental conditions inside those boxes. We cut down forests, drain wetlands, extend landmasses into the ocean and tamper with the ocean floor and coastal shelves. We run hundreds of millions of machines which expel various exhaust round the planet. We breed and multiply (both ourselves and our animals). We transform ecosystems, etc. etc.
The question is: how big an impact are we having, and especially how big an impact relative to pre-existing patterns, and what can we "do" to mitigate our impact (assuming that a rational analysis suggests clearly that we NEED to mitigate our impact).
Using you as an exemplar of "climate concernists" (a more polite way for me to say "hysterics"): I see virtually no consideration of ANY of the factors I have outlined above.