Sir David Attenborough has warned that humanity is doing its "damnedest" to stop the world recovering from the effects of climate change.
People "can't afford to be fatigued" about the threat of global warming, the 89-year-old broadcaster said, and the situation can, at best, get "less worse".
His comments come shortly after world leaders agreed a deal to cut global greenhouse emissions following climate talks in Paris.
The lifelong naturalist had been very vocal in the build-up to the summit, saying the world faced a "hideous problem".
Speaking to the Daily Telegraph magazine, Sir David said improvement can only be achieved through "very, very" hard work.
Referring to the problems facing the environment, he said: "Wouldn't it be nice if you didn't have to worry about it? But you can't afford to be fatigued.
"If we're lucky and we work very, very hard, they're going to get less worse."
Sir David, while confident that nature has the ability to recover, added: "We're doing our damnedest to prevent that now."
His latest documentary series, The Great Barrier Reef, will start on BBC One on December 30.