Totally Cooked: Episode 21 – What is net zero, and what happens when we get there?

Join hosts Sarah Perkins-Kirkpatrick and Iain Strachan as they welcome Associate Professor Andrew King and PhD candidate Aditya Sengupta for a deep dive into the science, politics, and post-zero implications of net zero emissions. What does net zero actually mean, when did the concept enter our vocabulary, and why is reaching it so urgent? From the cumulative effect of atmospheric carbon to the role of natural sinks like forests and the Southern Ocean, the episode builds a grounded understanding of what we’re working towards — and how far away we remain.

The conversation then turns to what happens beyond net zero: a world that is in many ways still getting worse even after emissions balance out. The guests explain the concept of overshoot — why we’ll likely exceed 1.5°C of warming before potentially coming back down — and walk through what we know, and what we urgently don’t, about a post-net zero climate. Andrew’s research reveals that the Southern Hemisphere, and Australia in particular, faces a harder trajectory than the Northern Hemisphere due to ocean thermal inertia. Aditya’s PhD work on the El Niño–Southern Oscillation shows that whatever changes we’ve already driven in ENSO variability will be locked in once emissions stop — for centuries.

So turn on a fan and buckle up as Totally Cooked looks into a warming world and what Net Zero really looks like as we tangle with 1.5°C and beyond.

Iain records Totally Cooked on the lands of the Bunurong People of the Kulin Nation. Sarah records Totally Cooked on the lands of the Ngunnawal and Ngambri people. We pay our respects to Elders past, present and emerging and recognise their unique and continuing connection to the land, skies, waters, plants and animals.

Show Notes

In this episode, we look at:

• What net zero means — the balance between greenhouse gas emissions and their uptake — and how the term gained traction at the UN from around 2014 before becoming central to the Paris Agreement.
• The cumulative carbon effect: warming reflects the entire stack of emissions since the industrial revolution, not just today’s output — which is why reaching net zero sooner carries enormous consequences for how much damage is locked in.
• Natural carbon sinks — reforestation and the oceans — with the Southern Ocean playing a particularly critical role, estimated to absorb around 60–70% of human-caused CO₂ emissions.
• The risk that ocean sinks become less effective: acidification reduces uptake efficiency, and stored heat in deep-ocean layers can be re-released as circulation continues — with no reliable timeline yet on when this tipping begins.
• Carbon Dioxide Removal (CDR) technologies — including direct air capture, BECCS, and geological carbon storage — are still energy-intensive, early-stage, and nowhere near viable at the scale required; durability of storage remains the central unsolved problem.
• Overshoot: we are on track to exceed 1.5°C of warming, and bringing temperatures back down will require net negative emissions — removing more carbon than we emit — a far more demanding target than net zero itself.
• Locked-in consequences: even under net zero, sea level rise continues, driven by ocean thermal expansion and ongoing ice melt — a consequence the guests describe as essentially irreversible on meaningful human timescales.
• Hemispheric asymmetry post-net zero: Northern land areas are expected to gradually cool once emissions stop; the Southern Hemisphere, dominated by ocean, will continue warming — leaving Australia particularly exposed.
• Arctic vs Antarctic sea ice: Arctic sea ice is projected to stabilise at whatever level it reaches when emissions stop; Antarctic sea ice is expected to keep declining due to sustained Southern Ocean warming, even under net zero scenarios.
• Aditya Sengupta’s PhD research shows that ENSO variability increases under continued emissions — and the greater swings between El Niño and La Niña events will persist for centuries once emissions stop, locked in at whatever level of warming was reached.
• Australia’s claimed emissions reductions are primarily the result of reduced land clearing from the mid-2000s, not cuts to energy or industrial emissions — a distinction the guests flag as a significant credibility problem for Australia’s net zero accounting.
• Net zero as a potential loophole: existing carbon offset markets already demonstrate how impermanent or low-quality sequestration can be presented as genuine emissions reduction — a dynamic that could scale as CDR technologies are deployed under political pressure.

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This episode will be released and available to stream and download on Friday 15th May, 2026.

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Because it’s time to feel empowered, not overwhelmed. Totally Cooked is a science-backed, straight-talking podcast about weather, climate change, and what it all means for life on Earth – especially here in Australia.

Hosted by climate scientist Sarah Perkins-Kirkpatrick and science communicator Iain Strachan, Totally Cooked breaks down how human activity is changing the Earth’s systems—from our skies to our seas—and what we can do about it.

From greenhouse gases to fire weather, supercomputers to Antarctic ice cores, this is climate science without the jargon, and where no subject is too complex or controversial.

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