The Meaning of Net Zero — Myles Allen

What is net zero?

Easy right? Surely, even LLMs can’t mess this up: “Net zero in terms of climate change refers to achieving a balance between the amount of greenhouse gases (GHGs) emitted into the atmosphere and the amount removed from it.” (Bard) WRONG. ❌

On Multiverses this week Professor Myles Allen of Environmental Change Institute (ECI), University of Oxford and Oxford Martin School tells us what he and other scientists really meant by net zero when they introduced it in COP 21 (Paris 2015).

Listen to get the full account. But here’s the short version:

🌍 Net zero does not mean holding GHGs constant in the atmosphere by balancing sources and sinks to it

🌍 … That would lock in (a lot) more warming

🌍 Net zero means balancing the flow of carbon to/from the Earth’s crust

🌍 … And letting natural sinks gradually reduce atmospheric levels

🌍 … Preventing warming beyond 2050.

Myles also makes a strong case that, if we want to hit the 2050 goals we need to invest more heavily in large-scale geological carbon capture and storage. Many climate activists worry that such a policy would detract from the progress of renewables and give the fossil fuel industry carte blanche to continue emitting. But Myles points out that our reliance on fossil fuels is not falling as quickly as we need, and CCAS is technologically viable, economically feasible, and essential to reaching true geological net zero.

(00:00) Intro

(2:29) What is net zero?

(4:12) Net zero is not a stable state but dynamical

(6:20) If we stabilise concentrations of CO2 we would see half as much warming again

(9:10) The meaning of net zero is often confused

(12:20) The danger of carbon accounting double counting

(16:56) The difficulty of establishing additionality

(19:52) Geological net zero is what was originally meant by net zero

(21:30) There are no significant natural sources or sinks of carbon between the biosphere and geosphere

(27:25) COP 28: the fossil fuel industry has got to be part of the solution

(30:50) “It is almost dangerous to claim it’s possible to solve the climate crisis without getting rid of CO2 on a very large scale … injecting it back into the Earth’s crust”

(32:30) Phasing out fossil fuels altogether is effectively letting the industry off the hook

(32:45) To what extent can we trust the fossil fuel industry? The potential dangers of CCAS

(35:30) “The cost with today’s technology of recapturing CO2 from the atmosphere and storing under the North Sea … “ is such that the natural gas industry could recapture all emissions and still be profitable at current prices

(40:10) Carbon pricing has failed: people do the cheapest thing first and the costly, slow-to-develop things (e.g. CCAS) are not coming fast enough

(42:20) The difficulty of getting a carbon capture flywheel going

(45:05) Intermittent energy supply is not a problem for carbon capture

(45:45) Is biochar a viable alternative to geological carbon capture?

(47:08) Biochar can’t hit the scale we need

(48:55) Extended producer responsibility

(50:10) eFuels (synthetic fuels)

(50:44) Final comments: we have the technology but we need to be realistic, we need to start taking carbon back

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