Over the past century, the Earth’s average temperature has increased by around 1°C, seas have risen, and news reports of extreme weather conditions have become worryingly commonplace.

Amid mounting concern, many scientists and engineers are looking at ways of going beyond the mere reduction of emissions and taking more active measures to tackle this threat to the planet. Potential solutions put forward include planting vast numbers of trees, employing technological means to remove carbon dioxide from the air, and geoengineering the atmosphere to reflect sunlight. NOVA documentary Can We Cool The Planet? (Thursday 4^th March, 8.40pm) joins both scientists and sceptics for a sober examination of the technologies that could help us defuse this ticking time bomb by seeking to restore ecological balance.