"We cannot be radical enough with dealing with these issues," he told politicians on Wednesday.
"If the world climate change goes on as it is we are going to be facing huge problems with immigration. Large parts of Africa will become even less inhabitable than they are now and there is going to be major upsets in the balance between our national boundaries."
Mr Attenborough, who has been making nature documentaries for almost 70 years, named Australia in his damning speech as one of the countries worst affected by climate change.
"I will never forget diving on the [Great Barrier] reef about 10 years ago and suddenly seeing that instead of this multitude of wonderful forms of life, that it was stark white, it had bleached white because of the rising temperatures and the increasing acidity of the sea," he said of his return since first diving there in the 1950s.
And in response to a question about climate change sceptics, he said the "voice of disbelief" should not be stamped out but that he hoped leaders in Australia and the US would come on board.
"Australia is already facing, having to deal with some of the most extreme manifestations of climate change," he said.
"But both Australia and America those voices are clearly heard."
Known for his nature documentaries, Mr Attenborough said he was hopeful that the world was on the cusp of great social change due to young people speaking out about the climate crisis, comparing the forthcoming attitude shift to how views changed regarding slavery.
"There was a time in the 19th century when it was perfectly acceptable for civilised human beings to think that it was morally acceptable to actually own another human being for a slave. And somehow or other, in the space of 20 or 30 years, the public perception of that totally transformed," he said.
"I suspect that we are right now at the beginning of a big change. Young people, in particular, are the stimulus that’s bringing it about."
Speaking about his shift from entertainer to climate advocate, Mr Attenborough said he didn't have a choice.
"If you become aware of what is happening, you don't have any alternative," he said.
"I feel an obligation. The only way you can get up in the morning is to believe that, actually, we can do something about it. And I suppose I think we can."