Physicist Stephen Hawking said pollution coupled with human greed and stupidity were the biggest threats to humanity.

Near the time of his death, the late Stephen Hawking remained convinced that the human race would require a “Planet B” if the species hoped to continued its existence.

Hawking believed that climate change would be humanity's extinction event.

Via BBC:

"We are close to the tipping point where global warming becomes irreversible. Trump's action could push the Earth over the brink, to become like Venus, with a temperature of two hundred and fifty degrees, and raining sulphuric acid," he told BBC News. ... "Climate change is one of the great dangers we face, and it's one we can prevent if we act now."

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The astrophysicist argued that humans were diminishing the Earth’s resources far faster than nature or technology could possibly replace them.

Hawking blamed human greed and stupidity for the impending climate disaster.

“We certainly have not become less greedy or less stupid,” Hawking told Larry King last year. The population has grown by half a billion since our last meeting [six years prior], with no end in sight. At this rate, it will be eleven billion by 2100."

Hawking took the view that humans were inherently destructive and selfish. He was skeptical of any human efforts to rein in climate change due to these characteristics.

Via BBC:

"I fear evolution has inbuilt greed and aggression to the human genome. There is no sign of conflict lessening, and the development of militarised technology and weapons of mass destruction could make that disastrous.

Because of his views on human nature, Hawking saw interplanetary relocation as the only effective means for the species to survive.

"The best hope for the survival of the human race might be independent colonies in space."

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