Scientists say the effects of climate change are no longer subtle, as the death toll from extreme weather events mounts.

Wildfires and heatwaves have killed more than 200 people in the northern hemisphere, in recent weeks.

Pennsylvania State University climatologist Michael Mann told Mike Hosking says extreme weather events are becoming increasingly common.

"The cost of climate inaction is now already apparent. We are starting to see impacts that really challenge our adaptive capacity."

He says it is the global nature of the record weather events that makes this summer so significant.

"I think we'll look back on this summer as the summer where the impacts of climate change we're no longer subtle."

LISTEN ABOVE AS MICHAEL MANN TALKS TO MIKE HOSKING