Humans with spears can take on elephants. You'd probably have to go back to the invention of fire for elephants to drive humans out. Intelligence is a huge advantage, humans can make walls, have pike formations, farm fields, burn down forests, etc.
A bull elephant is the true king of the jungle. But a lot of humans with zero self-regard could take down maybe one or two elephants at a time.
Perhaps an ancient Roman legion with a ballista - and balls of steel - could do some damage.
But you can only stop a herd of elephants that work together with modern technology.
The only early walls that can stop elephants would would be castle walls and thicker, and those are major projects that you'd have to undertake while getting tusked and stomped. Maybe ditches would work better, or caltrops.
We don't need to speculate. Roman legions frequently encountered elephantry and absolutely trounced them. The Romans then adopted war elephants briefly, before dropping them as totally impractical.
IIRC they saw initial success but saw diminishing returns as it was figured out that they scare quite easily by fire, loud noises, pike formations, etc. If you manage to panic an elephant still in the enemy lines it can do quite some damage to their troops.
Hannibal did terrify Rome with them for a while, but Scipio Africanus figured out a very simple strategy to defeat them, which won the second Punic war for Rome at the battle of Zama. He just made corridors in his formation and channeled the elephants down them, which then ran away scared from the battle all together.
Those were Indian elephants, not the much larger and more aggressive African, and they were used in small numbers - 20 or so. The main defence was to scare them or to lure them into a bad position.
I'm envisioning all elephants working together with discipline and coordination which would make it nearly impossible to stop them.
African elephants contribute greatly to deforestation. They enjoy knocking trees down for some reason[1]. And there's no doubt that deforestation can effect local climate change.
You sure about that? Most likely they are having an extremely measurable effect, it's just the effect is maintaining the status quo. Do you really think that the climate in Africa wouldn't change if forests were permitted to grow? Remember that climate is a complex dynamical process full of feedback loops. If anything, given the size of the landmass, allowing the savannahs to become dense forest would be a huge source of carbon capture.
Also I deny the premise that all climate change is bad prima facie, although again because complex dynamical system it can be impossible to predict the eventual outcomes. Nevertheless, a climate change like greening the Sahara could at least potentially be a net positive for humanity.
The point is that a sudden change in climate can't be blamed on them continuing to do what they've been doing for millions of years.
Now I highly doubt that an elephant occasionally knocking over a tree is the only thing holding back the continent from being forested, especially given that many elephants live in densely forested areas, but if for the sake of argument we assume that their behavior is a major factor, you still need to explain why their behavior, and thus that forcing function acting on the environment, would suddenly change.
> Now I highly doubt that an elephant occasionally knocking over a tree is the only thing holding back the continent from being forested, especially given that many elephants live in densely forested areas
Indian and African elephants are quite different ecologically speaking.
> but if for the sake of argument we assume that their behavior is a major factor, you still need to explain why their behavior, and thus that forcing function acting on the environment, would suddenly change
I never claimed it would suddenly change, I claimed that it's been consistent and has maintained a status quo.
