It's a disaster. Like always when humans intervene in key larts of the ecosystem and totally screw up the network effects.
Another story showing the vast effects of such interventions is the story of the wolf in Yellowstone.
"Nature" is nothing but the fragile status quo of a system in constant flux.
Natures status quo tends to be quite robust absent discontinuous changes. If one season there was a bit less rain, population sizes adjust and everything keeps working. A bit warmer, a bit windier, etc, continuous effects are dealt with in some robust manner.
Only when there are discontinuous changes then dramatic things happening. A meteor impact is such an event, some island gets reachable and suddenly flooded by some species, this kind of thing. But in nature such events are rare. Humans introduce such event all the time. Instead of an island getting reachable, we drive between them with boats or bring animals as pets or plant some nice flower from a different continent that gets invasive. Or modify genes or burn up millions of tons of coal.
We humans introduce those events at a massive scale, which is an entirely different quality than random changes in nature.
The selfish human decision to eradicate nuisances is just as random as the selfish decision of a predator to find new lands and drive local animals to extinction.
Most of our our eradication is not intentional, usually just hunting or eating a species out of existence. We are just dumb predators doing what successful predators do.
> We humans introduce those events at a massive scale, which is an entirely different quality than random changes in nature.
In the face of ice ages, our eradication attempts are no more impressive than a child killing ants in their backyard. The only thing in this regard that is truly impressive is our delusions of grandeur.
Granted, we gain little from messing with nature, but our attempts to maintain the status quo is guaranteed to fail. Nature is the furthest from a constant as one could possibly get, and species and ecosystem are ephemeral at best.
We don't just do this the way other predators do, by killing them to eat them. No, most of them are "mistakes" because we don't care.
[citation needed] - and for that matter, an estimate for eradication caused by other species for comparison.
(A good counter here would ask me the same for ice age extinction counts.)
> We don't just do this the way other predators do, by killing them to eat them.
Predators kill for food, fun and frustration.
Any outdoor cat owner would be able to tell you that predators don't kill to eat, as they clean up the daily lot of dismembered birds and rodents in their garden.
> No, most of them are "mistakes" because we don't care.
You think not caring about what we kill is a unique property to us?
We were randomly created though, right?