Sir David Attenborough has said “you can’t be radical enough” in dealing with the pressing climate crisis, as he outlined the “great problems” that the planet is facing in 30 years time.

Speaking to the government’s committee on climate change, Sir David was quizzed on whether the UK’s new legal “net zero” target for 2050 was sufficient or whether calls from campaigners for a 2025 goal was realistic.

The Blue Planet presenter said: “You can’t be radical enough in deal with issues at the moment.”

“The question is what is practically possible, and how can we take the electorate with us in dealing with these problems.

He added: “Dealing with problems means we’ve got to change our lifestyle.”

“I’m OK for the next decade, all of us are OK, we won’t face the problems that are coming.

“The problems of the next 20 to 30 years are great problems that are going to cause great social unrest and cause great changes in what we eat and how we live.”

Recalling the most vivid example he has seen of the changing climate, Sir David spoke of revisiting the Great Barrier Reef and seeing how it had bleached because of rising temperatures.

He told that when visiting the Australian landmark in the 1950s he had “the extraordinary experience of diving on the reef and suddenly seeing this multitude of fantastic beautiful forms of life.”

But of returning 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”.

Asked if he was optimistic climate change could be tackled, he said: “I’ve no idea as to what the future holds, I see no future in being pessimistic.

“I feel an obligation, the only way you can get up in the morning is to believe we can do something about it, and I believe we can.”

He said the UK’s record on tackling climate change “is pretty good”, adding that the coal-reliant industrial revolution which triggered the level of destruction to the climate we are witnessing.

“As it was us who started the problems, and if we are now taking a lead in solving the problem that only the right  and responsible thing to do,” he told the audience, which included MPs and young people.

He earlier said that public attitudes towards the environment had been “transformed” – drawing a parallel to changing attitudes to slavery in the 19th century.

When he started out in natural history, Sir David did not talk about climate change, because “we didn’t know, I didn’t believe we could change the climate, or worse the changes we were going to inflict were irreversible, which they are if we go on as we are.”

And he said: “I’m not by nature a propagandist”, but added “if you become aware of what is happening you don’t have any alternative”.

The naturalist also said the voices of “disbelief” on climate change should not be stamped out and it was important that they should be heard in public.

But he said: “I’m sorry there are people who are in power internationally, notably of course the US, but also Australia, which is extraordinary because Australia is having to deal with some of the most extreme manifestations of climate change, and these voices are already heard.

“One hopes the electorate will respond to that.”

On the issue of plastic, Sir David said: “I’ve been going on about plastics for 20 years. Anybody who swims know that, or anyone who travels can see, the horrors of what plastic pollution can do.

“I’ve been putting it in programmes for years, and nobody took any notice”.

Then a two-minute clip in his programme Blue Planet II “rang a bell with people”, he added.