they’re onto us!

Watching from afar, extraterrestrial beings might view changes in Earth’s atmosphere as symptomatic of a civilisation growing out of control – and take drastic action to keep us from becoming a more serious threat, the researchers explain.

Shawn Domagal-Goldman of Nasa’s Planetary Science Division and his colleagues compiled a list of plausible outcomes that could unfold in the aftermath of a close encounter, to help humanity “prepare for actual contact”.
The Guardian, 19 Aug 2011

see also – Say what?