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Cumulative CO₂ emissions explain most future global warming, assuming sufficient action on non-CO₂.
Distributing a remaining carbon budget of 500GtCO₂ with a linear decline (black) leads to net-zero ~2045.
Depending on short-term action, many net-zero years are possible.
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Distributing a remaining carbon budget of 500GtCO₂ with a linear decline (black) leads to net-zero ~2045.
Depending on short-term action, many net-zero years are possible.
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If emissions decline exponentially, also in the 'Raupach curve', net-zero emissions never occur & the remaining carbon budget is never exceeded. Net-zero is not a necessity, but a modelling outcome.
The 'Raupach curve' is explained here: https://iopscience.iop.org/article/10.1088/1748-9326/10/10/105004
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The 'Raupach curve' is explained here: https://iopscience.iop.org/article/10.1088/1748-9326/10/10/105004
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Most scenarios are based on cost-optimisation to a 2100 target, which means the temperature can peak & decline, overshooting the 2100 target before returning to it by 2100.
These scenarios are where the net-zero ~2050 come from (2059 in this figure).
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These scenarios are where the net-zero ~2050 come from (2059 in this figure).
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This all means that net-zero emissions are needed, but the net-zero year depends on how the remaining carbon budget is distributed over time.
https://www.carbonbrief.org/explainer-will-global-warming-stop-as-soon-as-net-zero-emissions-are-reached
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https://www.carbonbrief.org/explainer-will-global-warming-stop-as-soon-as-net-zero-emissions-are-reached
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Scenarios have been performative & force us to think about net-zero in a particular way.
There are scenarios that don't reach net-zero CO₂ emissions until after 2100, but we only hear about the medians, which are scenarios based on 2100 targets & allowing overshoot.
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There are scenarios that don't reach net-zero CO₂ emissions until after 2100, but we only hear about the medians, which are scenarios based on 2100 targets & allowing overshoot.
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