It’s just another example of human arrogance to think we will have any lasting impact on the planet
Even if you unleashed every nuke on the planet, burned every bit of carbon available.
it wouldn’t be a fraction of the impact that the tectonic plate shift had, asteroids, heating and cooling periods , the magnetic pole reversals.
The planet will eventually shrug us off like a case of the sniffles.
On this, I disagree (except the last sentence, anyway).
There's a couple of things to unpick in the 'can humans actually have lasting impact' topic.
Firstly, can ANY biological organism have a lasting impact on the planet? This one is very easy to answer, and it's a resounding yes. To prove it, one can just look at our atmosphere and the geological record.
3.5bn years ago, an insignificant little microbe evolved an insignificant metabolic pathway, and fundamentally changed the course of the planet. That pathway? Photosynthesis.
Photosynthesis, for the first time in 2bn years, placed substantial amounts of oxygen into the atmosphere. The impact was, and is, profound. Earth is the ONLY planet in the solar system with much free oxygen. Biological processes are the only known mechanism by which that can occur. Oxygen is highly reactive with basically everything and so without a constant, high level source of production, it rapidly gets removed into oxides. See Mars or Venus as examples.
The impact of this Great Oxidation Event has persisted for billions of years, more than half the time the Earth has existed. It is significant and it is long lasting. It massively changed climate, and geological processes, life, and everything else. It resulted in a drop in atmospheric CO2 from 97%, to levels not
that different from today and subsequently caused a global mass extinction of anaerobic bacteria (ie basically all life forms at the time) more wide ranging and comprehensive than the Permian Great Dying, or the Cretaceous asteroid impact.
The sequestration of CO2 by plant life in the Carboniferous is another, although far less impactful, example of this.
Secondly. Are humans able to have a lasting impact? The answer here is also a yes. In 1907, humanity developed synthetic plastics. They've since spread to every corner of the planet, from Everest, to the atmosphere, to the deep ocean, to every living organism. Plastics will be a key marker of humanity in the geological record, measurably changing the composition of sedimentary rocks from this period in a way detectable for
at least millions of years. Probably an impact detectable long after the demise of our own species.
Humans have also significantly changed the fossil record, in a way that will be detectable for a very long time. Not only by dumping a load of our own organic matter into it, but also by significantly changing the range of other organisms. The mega faunal extinctions of 50-000-13,000 years ago will be observable in the fossil record of this planet for all time (or at least until the Sun goes full red giant and vaporizes everything). So will some of the impacts of our agriculture in terms of ranges for species, relative prevalence of those species, etc. Maize in Europe, Potatoes in Europe, 2 row Barley in the Americas as examples. So will the elimination of diseases like smallpox, rinderpest and probably more in the years to come. That is a profound and long lasting impact.
CO2 in the atmosphere is also a
potential impact here. We know that life can change atmospheric composition (photosynthesis). We know that life has in the past impacted (reduced) CO2 levels (carboniferous, photosynthesis). We know that these changes in the past have lead to major changes in biological diversity and the ragne of other organisms (mass extinctions). We know we are releasing CO2 into the atmosphere that has stayed out of it for hundreds of millions of years. Will that have an impact? Up for debate, but it doesn't seem outside the realm of possibility, and it also doesn't seem impossible that this impact may persist for a long time.
Finally, nuclear holocaust. If we as a species go down that road, it will have immense impacts on this planet that will again persist for a very long time in the fossil record, and in geology. We might not be around to care, but the impact to all ecosystems will be profound, and persistent, and measurable, for billions of years, just as every other mass extinction (some of which can also be laid at the feet of living organisms) has been.
Going back to your suggestion that this is arrogance. I'd simply ask: Is it arrogance to think that humans may have a measurable and long lasting impact on the planet when so many other organisms have already done so?
I don't think so, even if personally I think we're rather overstating our current impact versus the wider geological context, mostly due to proximity.
The only point up for debate is if this impact is profound enough to 'matter' and if it is, do we plan to do anything about it. That's a political question, not a scientific one in my mind, and not one we have many good, evidence based, answers for.
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