A simple example;
4.5 billion years of natural evolution of the earth, which sequestered trillions of gallons of CO2 (oil) deep underground where it could not do any damage to the chemistry of our atmosphere.
Along comes man and we extract all that sequestered CO2 back into the atmosphere and, in addition, cutting down the trees which eat CO2 and release oxygen, doubling the adverse affect on our atmosphere and creating an imbalance in global temperatures. Over the past ten years we have been witnessing the slow but increasing instability of weather patterns as we speak.
I am not saying that the weather on earth was ever in perfect balance, but we know the current patterns indicate strongly that human industry and "development" are in great part responsible for the current AGW and the intensification of natural events.
There are no indications of other natural causes, other than human overpopulation and overuse of resources to the detriment of all other life, except the insect. Their very simplicity makes them adaptable to almost every possible environment, including building immunity to every insecticide we can throw at them, such as DDT.
But then, insects have been practicing agriculture, farming, husbandry (herding) for millions of years before man came along. The difference is that the insects practiced these forms of domestication by completely natural means, without artificial fertilizers or releasing deadly toxins into the atmosphere.
IOW, the insect lives in perfect balance with its environment. Humans do not.