huh, i agree in principle that we're not ALWAYS the SOLE cause, but humans really have achieved an unprecedented level of power and ability to positively or negatively affect species and the world. i mean, with the 100-megaton nukes we have now, we could theoretically crack the earth's crust and pretty much turn the planet into a moonscape.
so maybe we're not more powerful than an iridium-heavy asteroid. but we're probably AS powerful.