Aliens to attack earth?

US-based scientists have predicted aliens could be set to invade Earth if people do not cut down on their carbon emissions.

US-based scientists have claimed an alien invasion could be on its way if people do not cut carbon emissions.

The experts, from Nasa and Pennsylvania State University, believe extraterrestrials could attack earth in order to defend their planets from a perceived threat that comes from the changes in Earth's temperature.

Shawn Domagal-Goldman, from Nasa's Planetary Science Division, and other colleagues listed possible outcomes that could occur if aliens landed in an report entitled 'Would Contact with Extraterrestrials Benefit or Harm Humanity? A Scenario Analysis'.

The researchers explained: "These scenarios give us reason to limit our growth and reduce our impact on global ecosystems. It would be particularly important for us to limit our emissions of greenhouse gases, since atmospheric composition can be observed from other planets."