Billionaire Elon Musk - co-founder of electric car company Tesla Motors - says climate change will bring about a refugee crisis of catastrophic proportion.

At a speech in Berlin, Musk said Europe's current wave of asylum-seekers would pale into insignificance compared to the masses displaced when fresh water becomes scarce, food supplies break down and weather systems changes in coming years.

“Today's refugee problem is perhaps a small indication of what the future will be like if we do not take action with respect to climate change,” Musk said in his speech at Germany's Federal Ministry for Economic Affairs and Energy.

“Today, the challenge is in terms of millions of people, but in the future, based on what the scientific consensus is, the problem will be in the hundreds of millions and much more severe.

“I think it's very important that we take action today to recognize that we are making a very significant change to the chemical constituency of the atmosphere and oceans.

“One that is almost impossible to reverse.”

But in the US, where Musk is based, climate change remains a contentious topic.

Powerful lobby groups acting on behalf of companies that benefit from large-scale carbon emitting industries, are paid to create doubt about the scientific consensus of mankind’s role in warming the planet.

In Germany, a nation Musk called “the best in the world when it comes to solar power”, the scientific facts of the climate are more accepted.

Even so, Musk said Germany has a long way to go.

The country has aggressively transitioned to renewable energy, but remains dependent on vehicles running on gasoline and diesel.

“If you go 20, 30, 50 years in the future, what do you say to your kids or your grandkids? It's almost, like, scientists have all said that these bad things are going to happen, it's, like 97 percent,” Musk said.

“So, to say to your kids or grandkids, like; ‘Did nobody tell you?’ No, everyone was telling us.

“So why didn't you do anything?’ ‘What's the answer?’ I think it's very important that we do something.”