Developing world 'baring the brunt' of climate change -PM Johnson

"...it's the developed world that over 200 years has put the carbon in the atmosphere that is causing this acceleration of climate change. And so it really is up to us to help them," Johnson said.

Johnson has called on wealthy countries to meet a pledge to spend $100 billion a year to tackle climate change as he prepares to host a United Nations summit starting at the end of October.