Last Night's Viewing: Supersized Earth, BBC1 Bradley Wiggins: a Year in Yellow, Sky Atlantic

I always took it as proof of a benevolent God when you'd sit down for geography and find out you had to do nothing more than watch a documentary made in the mid-Eighties about a local slagheap. Dallas Campbell's Supersized Earth is precisely the sort of viewing you'd go mad for, if the alternative was a geography lesson. And even though there isn't much else on telly tonight, there are probably more things you can think of to do than watch it.

Don't get me wrong, there's a keen audience (myself included) for the sort of geeky anthropo-nerdiness that this programme promises, with its focus on urban planning and latter-day infrastructure. The mainstreamification of academic authors such as Jane Jacobs and Edward Glaeser on the subject means that the airing of a series such as this one was about as likely as flooding in Venice.

"We're redesigning our world," Campbell intones like a commercial-radio tour guide, as the cameras pans around the globe and onto his fashionably slim-cut jeans and boots. (At various points he is clearly flagged up as the Brian Cox of the urban science circuit, to a soundtrack of middling electro and a wardrobe that mixes sports-casual with performancewear rather winningly.) "Our generation is changing the face of the planet as never before."

"It's testament to what we can do now," he continues, hanging by what looks like some dental floss off the top of the Burj Khalifa. It's testament to him, I'd say instead, that he hasn't yet soiled himself. What shapes Supersized Earth are the supersized segments of Campbell's derring-do: he cleans the windows of an 800-metre-high tower block; he removes a horse's skull that has been clogging up a Mexican sewage pipe; he eats a potentially poisonous raw mushroom in a small flat in Hong Kong – this last is a mistake rather than any profound comment on the housing crisis there.

But Campbell's breakneck tour of the world's urban hotspots doesn't give the viewer enough credit: there is too much time devoted to the hypothetical, the not quite factually statistical. Infographics collate how far all the cities in the world would spread if laid end to end – but they haven't been. Their tallest buildings are presented as next-door neighbours, when they're not. It's a frustrating and pointless five minutes that could have been spent investigating some of the most fascinating environments on the planet.

When they come, these snippets are well worth seeing – from Julio, South America's Jacques Cousteau of crap, who plunges into "las aguas negras" so that his hometown doesn't drown in its own effluent, to the Chinese engineer who can throw up an 18-storey flatpack tower block in a week.

This may be a programme about cities, but it is fundamentally about the humans who people and personify them – and there should have been more focus on them.

Meanwhile, the man we all wish we knew wants nothing to do with us. Bradley Wiggins: a Year in Yellow paints everybody's favourite Paul Weller lookalike as a veritable Heathcliff on two wheels. "He's a bit of a twat, yeah," says Wiggins's wife of his cycling persona. "He's not cruel or selfish, it's because he can't see anything apart from where he's going."

You get the impression from interviews with coaches Dave Brailsford and Shane Sutton that these earthy pedallers don't much talk about their feelings. But Wiggins's crunchy demeanour – even more brittle after talking about his late father – softens eventually. This man who so hates the limelight has to sit through an entire school assembly about his life. He laughs, he looks stricken, he cries a bit on to a novelty card the children have made for him. And suddenly, I see what all the fuss is about.

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