Mark Lynas is the author of numerous books on the environment. His latest is Our Final Warning: Six Degrees of Climate Emergency. He also advises former Maldives president Mohamed Nasheed on climate, and works with the 48-member Climate Vulnerable Forum.

'I started off doing grass roots activism... sometimes it felt like few people were listening,' says @mark_lynas. 'Fast forward 20 years & we're on the cusp of a global transformation.' That transformation could well happen in the next 20 years – something previously unthinkable.

We can't solve climate change while keeping the developing world poor, says @mark_lynas. Climate change and fighting severe economic inequality are inseparable. The 'developed' north must pay for the south. 'There is no carbon budget left'.

There's still time to book your place & join @mark_lynas, @sarahbridle, @jurassicg1rl, @Ben_garrod, & @theAliceRoberts as they discuss the latest scientific insights on the ecological crisis. Tickets sold until 20:00. Live tweets to follow. #OneLifeOnePlanet