They come in (green)peace

Reducing greenhouse gas emissions might just save humanity from an alien invasion, according to researchers from Penn State University.

Humanity may be entering a period in which our rapid expansion could be detected by alien life forms because we are changing the composition of the Earth’s atmosphere - through greenhouse gas emissions - and this changes the spectral signature of the planet.

The study, published in “Acta Astronautica”, suggests that a preemptive strike would be likely because as a civilisation expands it becomes increasingly difficult to destroy.

Read more at Acta Astronautica