Buckle up for a trip back in time to the last ice age. We touch down in the mammoth steppe, and discover that this was a surprisingly productive ecosystem--it supported a high density and diversity of animals, including mammoths and other big hairy herbivores. So productive, it has been called the 'Serengeti of the North'.  And it turns out that the very nature of this ecosystem--the interactions between herbivores, plants, microbes in the guts of animals, microbes in the soil, little digging animals and even mineral grains--can help explain why so much carbon ended up stored in the permafrost ground of the Arctic. 

Tune in to explore the Pleistocene grasslands, and discover how large herbivores acted as 'bioreactors', enabling nutrient cycling to occur even in the frigidly cold conditions of the last ice age. Discover how plants swap carbon with microbes in return for nutrients in an elaborate trading scheme. Find out how decomposition can chop that spaghetti bolognese of organic matter we learned about in episode one into small pieces, which can then bind with minerals in the soil, becoming a very stable form of carbon in the ground.

Our experts on this show are Prof. Marc Macias-Fauria and Dr Jeppe Kristensen.

Co-hosts: Roberta Wilkinson and Sam Cornish
Reporting, editing, mixing and original music: Sam Cornish
Sound design: Jihad Zgheib