While some of the stories were a bit weak, the strand where a politician (Lyndsey Marshal) and a scientist (Peter McDonald) went to a climate summit in Copenhagen was beautifully written and performed. I think the amazing ambling polar bear might well be the best thing I’ll see on stage this year.

After the play you can join the climate change debate in the theatre foyer and discuss your views of the play and the issues it raises.

Book your tickets to Greenland now.

Greenland plays at the National Theatre until 2 Apri. Tickets from £12. Visit www.nationaltheatre.org.uk for more information.

There’s a secret world of fitness happening in London each morning. While the rest of us are creaking awake with coffee and trying to convince ourselves to have muesli and yoghurt instead of toast with honey (or even the full English), plenty of people are out peddling, paddling, pumping iron or pounding the pavement.

This morning I joined them.

Impressing even myself by rolling out of bed at 6.30am, I fronted up to the Parliament Hill lido (or Hampstead Heath lido, as it’s also known) just as it was opening at 7am. It’s an outdoor pool but fear of the cold did not deter me, and nor should it have, with water a balmy 22 degrees – exactly the same temperature as the morning air.

Between 7 and 7.30 you swim widths (27m) across the pool, which seemed odd at first but was actually quite pleasant, especially in my “flabulous” state of body. Swimmers switch to lengths (60m) from 7.30-9am, when the morning session ends.

The pool was full but not crowded with the usual assortment of young and old, fit and not-so – all sharing the joy of warm weather and wonderful water. They rely on a system of politeness rather than using lane markers and it all went swimmingly, if you’ll excuse the pun.

On my way out, I heard two regulars grumbling good-naturedly about how the recent heatwave meant the pool was far busier than usual and that they hoped a thunderstorm might drive some of us Jane-come-latelys away. I can see how they’d want to keep something so good all to themselves. But I’ll be back.

Check out Visit London’s list of places to swim outdoors in London. What’s your favourite pool?

This year, for its summer exhibition Radical Nature: Art and Architecture for a Changing Planet 1969 – 2009, the Barbican has cast its net wide in every sense of the word. The main action takes place in the Barbican Gallery with offsite installations on the Barbican’s Lakeside Terrace and in Dalston.

We liked Radical Nature, not just for its exhibits but for its earthy smells, surprises, apocalyptic sense of humour and space.

It’s all about the way, in recent years, nature and the environment has inspired artists and architects. The exhibition looks at the way these modern artists engage with the environment as they attempt to create some kind of harmony between man and planet.

Using both levels of the Barbican’s gallery space, the exhibition features 25 artists and architects. Described by the curator as “Frankenstein’s garden”, Radical Nature kicks off with a sad and eerie looking lone pine wolf on a trailer. One of Mark Dion’s Mobile Wilderness Units – the wolf demonstrates how man continually tries to turn nature into a palatable commodity.

Particular highlights for me included Anya Gallaccio’s Birch Tree. To create the installation the artist worked with a tree surgeon to source a tree which was destined to be felled. Once cut down, the tree was reassembled in the gallery space using metal bolts and wires. It’s very gentle and yet it screams “I shouldn’t be in here!”

Great stuff for children includes Henrick Hakansson’s Fallen Forest. It’s a tropical jungle flipped on its side and you can explore behind, around and above it. Green Room, 2009 is a simple wooden structure that you walk into. Once inside, a beautiful miniature garden is revealed and the mirrored interior walls create an illusion of infinite space, when in fact only once person can comfortably fit inside the structure.

Radical Nature is good stuff – serious, surprising and fun. The exhibition is on until 18 October. If you see it, let us know what you think.

Photograph by Lyndon Douglas, courtesy of the Barbican.