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

After listening to the Herders under pressure episode, Roberta sat Sam down to dive into some questions she had. For instance: to what extent can recycling help supply critical materials for the energy transition (like lithium, cobalt, nickel and graphite)? Join us as we consider this, reflect on the core justice issues for Sámi reindeer herders and consider what different pathways to net zero might look like.

Oula-Antti Labba spent much of his childhood in Finnish Sámiland helping his family with the traditional reindeer herding work. But this traditional livelihood is under dual threat: from climate change and industrialisation of Sámi lands. After experiencing "the lack of respecting indigenous rights" that accompanied permits for mining being granted without the consent of local communities, he decided to pursue a career in law to stand up for Sámi people--and indigenous people worldwide. 

While mining is not new in northern Scandinavia, much of the new exploration work is oriented towards finding critical minerals for the energy transition. Which means that, paradoxically, Sámi reindeer herders find themselves under threat from both climate change and our solutions to that problem. 

Join us as we navigate between reindeer herds, underground mines and the international courts, and ask--with the help of two economic geologists--what a brighter future could look like for Sámi communities, and how we might get there in the context of immense pressures.

Guests on the show:
Oula-Antti Labba, Sámi Council (now Ministry of Justice, Finland)
Postdoctoral researchers Anna Bidgood and Phil Rieger, from iCRAG, the Science Foundation Ireland Research Centre in Applied Geosciences hosted by University College Dublin.
Charlotte Chamberlain, University of Oxford (and producer on this show)

Polar Pod team:
Sam Cornish (reporting, editing, mixing, original music)
Roberta Wilkinson (co-host)
Charlotte Chamberlain (producer)
Jihad Zgheib (sound design)

Recorded during the UK's July heatwave, Sam and Roberta turn their thoughts north to cooler regions...

We tend to think of Arctic regions as harsh, frozen, crisp, cold. But professor Marc Macias Fauria invites us to consider parts of the Arctic landscape differently. In summer, he suggests, it is like a landscape of butter.

In this dynamic environment, the carbon locked up in frozen ground, or permafrost, is vulnerable. In episode 2, we looked at how carbon gets into the ground, and how the freezing temperatures help protect it from being decomposed by microbes, much like how we put food in the freezer to preserve it. Now, we ask, what happens to the carbon when we open that freezer, when permafrost thaws? 

And we’ll be discovering that there are a few surprises hidden down there.

In this episode, we take a close look at permafrost and how it is responding to climate change. This matters because the permafrost is acting as a giant freezer for vast quantities of carbon-rich organic matter--if the freezer thaws, microbial decomposition can lead to this carbon ending up in the atmosphere, causing further warming. So, how resilient is permafrost to change? 
We also discover how, as the ground thaws, it changes shape, and what this means for people's homes and infrastructure. We then learn about the importance of including local and Indigenous communities in the process of science conducted on their land. 
Our brilliant guests on this episode were Professor Chris Burn and Dr Loeka Jongejans.
Your Polar Pod team is Sam Cornish, Roberta Wilkinson and Jihad Zgheib.

Carbon-rich organic matter is just like spaghetti bolognese: a tangle of carbon chains that's vulnerable to being eaten. In order to keep your spag bol safe, special conditions are required (tupperware, fridge), and it's just the same for organic matter in the ground.

Why does this matter? As the climate warms, so does the very ground beneath our feet. And where that ground is frozen (large parts of Canada, Alaska and Siberia) warming can lead to thawing, allowing carbon-rich soil to come out of the freezer and be attacked by hungry microbes. As microbes consume organic matter in the soil, they produce greenhouse gases, which have the potential to further warm the climate more, leading to a possible positive feedback effect. 

In this episode, the first of a 5-part series on carbon in the ground, we explore how carbon gets into the ground in the first place, and what conditions enable it to stay there, locked away--or not, as the case may be. 

Listen in for canine and culinary analogies as our guests serve up bitesized facts with lashings of context.

Our wonderful guests on this episode were Professor Chris Burn, Dr Loeka Jongejans and Dr Jeppe Kristensen. We'll be hearing more from them in other episodes in this mini-series.

Your Polar Pod team is Sam Cornish, Roberta Wilkinson and Jihad Zgheib.