Steve Backshall: if I don't tackle climate change, what kind of world will my son grow up in?

The son he speaks of is seven-month-old Logan, and becoming a parent for the first time with his wife, Olympic gold medal-winning rower Helen Glover, has changed Backshall in more ways than he expected.

“I hate clichés or anything mawkish, but the second I became a father it was a lightning bolt and my entire perception switched, from a mainly selfish one to thinking about Logan and his future. I keep saying, ‘I want Logan to be able to see or do this.’ His generation will look back at mine with intense negativity as we’ve stood by and allowed a catastrophic decline in the world’s ecosystems and climate change to happen. I want to be proud of my legacy and I’m not.”

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Of course, Backshall is being unduly modest. His body of work has done much to educate and inform, from his debut in the 1980s, on the BBC’s Really Wild Show, through the Deadly 60 series of programmes and on to major TV expeditions.

He’s back on our screens this week and next as part of Blue Planet Live, a four-night outside broadcast from three locations around the world. Chris Packham will be filming in the Sea of Cortez off the coast of Mexico, looking into the health of whales; Liz Bonnin will be reporting from Australia’s Great Barrier Reef on attempts to re-grow the ravaged coral; and Backshall is in the Bahamas to raise awareness of the extinction threat facing sharks. (There is also a daytime spin-off focusing on the UK’s coastal waters.)

“If I go to sites now where I went diving with sharks just five years ago, they’ve gone completely. Other than vultures and frogs, sharks are the most threatened animal on the planet – largely from fishing – and it’s possible we could lose them in my lifetime. People would never tolerate this happening to dolphins. If we can convince viewers that sharks are amazing, or even to check their medicine for shark cartilage so they don’t buy it again, it all contributes.”

Having a son relatively late in life – he’s now 45 – has given Backshall cause to consider his own future in television. He’s spent at least eight of the past 12 months travelling across the globe to film an “old-fashioned exploration” documentary series called Undiscovered World, to be shown on BBC2 this spring.

“Five weeks after Logan was born, I went away on a six-week trip in the jungle and I had enough satellite phone reception to speak to Helen for a few minutes every few days. Babies develop so fast every day, so if I’m away for a few weeks, he’s completely different when I get back. Now he recognises me and is connected to me, going away is torture. It’s ten times tougher for Helen. She’s spent a lot of time in Cornwall with her family, but it’s still hard without your partner around.

“But this has been my pet project since the late 1990s. The first expedition was in Mexico’s Yucatán Peninsula, just five miles from Cancún, where there are huge caves as high as cathedrals, where no human’s ever been. In Surinam we spent weeks on rivers not even marked on maps.”

It was while climbing a treacherous rock face that Backshall realised his career needed to change direction. “Most of the time, the danger in my job is more perception than reality. But these expeditions are in environments you can’t possibly control. People have been close to being killed by rockfalls and if a boulder misses you by less than a metre you have a long hard word with yourself about what you’re doing. I’ve had enough of that now. I have a baby, so putting myself in danger doesn’t make sense any more. I’d like to go back to doing more wildlife and conservation programmes.”

Though parenthood is very evidently a joy to both Backshall and wife Helen, they have been through some desperately testing times. Twenty weeks into her pregnancy, Helen lost Logan’s twin; and while it’s something they’ll never get over, they’re grateful for the gift of their boy.

“We very much count our blessings,” he reflects. “The fact it was a struggle makes you much more appreciative of the miracle that he is. It’s absolute joy every time I come home and see Logan’s smiley face. He’s so utterly precious because you’ve felt a bit of the loss.” It’s not put them off wanting to expand their family – quite the opposite. And while Glover has put her Olympic career on hold, she hopes to be back for the Games in Paris in 2024.

“Helen wanted to start a family and be back in time for Tokyo in 2020, but it took us longer to have Logan than we expected – and we’re not done there. Helen’s from a family of five kids, so given a chance she’d have an army! She’s a phenomenal athlete – she had a six-pack only weeks after Logan was born, it’s ridiculous. Katherine Grainger took a silver at Rio at the age of 40 – by 2024, Helen will be 37 and should be looking for another medal.”

On top of everything else, the couple have moved from their houseboat in Berkshire – “I loved it and would quite happily have stayed on it for the rest of my life, but it’s not big enough to be raising a family on” – to a riverside eco-house that they’ve built and are hoping to take completely off-grid. It’s the perfect place to plan their next move.

“If Helen decides she wants to go back to competing, I like the idea of taking a bit of time out to be a dad,” says Backshall. “Five years ago I was a confirmed bachelor, obsessed with work, and now I’m married with a baby trying to figure out what the next stage of life is. I study biology for a living – I think there are certain things that, like it or not, are so ingrained within us that if we don’t realise them we’re going to end up unhappy. It wasn’t until I met Helen and we had Logan that I really recognised that.

“I’m at a big crux point in my life where there are going to be big changes over the next few years, and I’m really looking forward to finding out what they are.”

Blue Planet Live begins Sunday 24th March on BBC1 at 8pm