As a new warning is released by scientists that trying to offset our carbon emissions by planting trees alone won’t work, we investigate the role the Earth’s forests are playing in the fight against climate change.

Marnie Chesterton is joined by Mark Maslin, Professor of Earth System Science at University College London, to help answer our top five questions about trees and CO2.

We also speak to science writer and New York Times columnist Carl Zimmer about his new book ‘Air-Borne: The Hidden History of the Life We Breathe’, and what it tells us about what we’re breathing into our lungs each day.

After we reported on the plight of some of our UK wild bird species earlier this year, many listeners got in touch wanting to know more about one species in particular: house sparrows. To look at why their numbers have been declining so sharply, and what we might be able to do about it, we hear from Imperial College London’s Dr Julia Schroeder, who has been studying the birds for 15 years.

And Marnie is joined in the studio by Lizzie Gibney, Senior Reporter at Nature, to explore some of the fascinating research from around the world in this week’s science journals.

Presenter: Marnie Chesterton Producers: Clare Salisbury, Dan Welsh and Jonathan Blackwell Editor: Martin Smith Production Co-ordinator: Jana Bennett-Holesworth