Naturalist Sir David Attenborough has warned MPs that climate change will bring about "great social unrest" unless tackled.
The 93-year-old naturalist was giving evidence to Parliament's Business, Energy and Industrial Strategy Committee today as part of its inquiry into clean growth and international climate change targets.
When asked what the most vivid example of climate change he had witnessed was, the veteran broadcaster recounted revisiting the Great Barrier Reef and seeing how it had been bleached because of rising temperatures.
He first visited the Australian landmark in the 1950s, describing it as a "multitude of fantastic, beautiful forms of life".
But upon his return 10 years ago, he said: "Instead of multitudes of wonderful forms of life, I was struck by how it was bleached white because of the rising temperatures and increasing acidity of the seas."
Sir David also warned of "huge problems with immigration" as countries become less inhabitable due to increasing temperatures.
Sir David presented evidence to a panel of MPs
"The problem you're opening now is a very serious one. If the world climate change goes on, it is going to be facing huge problems with immigration.
"Large parts of Africa are going to be even less inhabitable than they are now, and there will be major upsets in the balance between our national boundaries."
He said it was important for people to begin changing their lifestyles in order to reach the UK's new legal net zero emissions target for 2050.
Announcing the target, Prime Minister Theresa May said there was a "moral duty to leave this world in a better condition than what we inherited".
Sir David said the issue of climate change was unlikely to affect him, but predicted "major problems" over the next 20 to 30 years.
"The problems of the next 20 to 30 years are major problems that are going to cause great social unrest and great changes in what we eat and how we live," he added.