So many people are so anxious to dismiss the idea that humans could have an effect on the climate.

Most of them have a vested monetary interest in maintaining a lifestyle that continues to exacerbate the problem. The real problem is related to the ease with which most people are happy to embrace the idea of the negligible.

Because a single individual has a "negligible" effect on the environment, they assume that the collective effect is also negligible. This is erroneous. Negligible does not mean none.

Negligible refers to the fact that human perception is too limited to be able to discern an effect, not that there is no effect.

The reality is that if you exist, you affect the environment.

Every breath you take alters the specific molecular composition of the world, both yourself and your surroundings. Human limitations of perception are irrelevant to the fact that living necessitates an environmental effect.

No one knows the overall impact of human activity on the environment, if for no other reason than the simple fact that more than six billion people have never existed in previous ages. However, to choose to look at that ignorance and equate "we don't know the effect" with "we have no effect" is egregiously wrong.

If you exist, you affect the world.