THREAD (of my #enova2020 presentation)
If 2.5°C is easy, why is 2°C hard?
The future is uncertain & scenarios are used to explore those uncertainties. But which scenarios are more likely & why is this important to know?
enova.no/enovakonferans…
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If 2.5°C is easy, why is 2°C hard?
The future is uncertain & scenarios are used to explore those uncertainties. But which scenarios are more likely & why is this important to know?
enova.no/enovakonferans…
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Baseline scenarios assume no climate policy through to 2100, nor climate impacts on society.
They show a wide range, with some baseline scenarios decreasing emissions while others showing rapid growth (& acceleration).
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They show a wide range, with some baseline scenarios decreasing emissions while others showing rapid growth (& acceleration).
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RCP8.5 (SSP5-8.5) is a particular baseline scenario, assuming both a fossil fuel intensive world, no climate policy, & no climate impacts to 2100.
RCP8.5 was selected as an outlier scenario 10 years ago, & it is even more of an outlier now given current developments.
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RCP8.5 was selected as an outlier scenario 10 years ago, & it is even more of an outlier now given current developments.
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With weak to moderate climate policy emissions may peak before mid-century & then decline.
Current & stated policies are consistent with ~3°C warming in 2100, between RCP4.5 & RCP6.0.
Why is this good news? It means <2°C may be easier than many assume...
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Current & stated policies are consistent with ~3°C warming in 2100, between RCP4.5 & RCP6.0.
Why is this good news? It means <2°C may be easier than many assume...
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3°C & rising in 2100 is not desirable, we want better!
To be consistent with the Paris agreement requires deep mitigation
• 1.5°C: 50% reduction by 2030, net-zero by 2050, net-negative thereafter
• 2.0°C: 75% reduction by 2030, net-zero by 2070, net-negative thereafter
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To be consistent with the Paris agreement requires deep mitigation
• 1.5°C: 50% reduction by 2030, net-zero by 2050, net-negative thereafter
• 2.0°C: 75% reduction by 2030, net-zero by 2070, net-negative thereafter
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Why are 1.5°C & 5°C outliers? The carbon budget helps explain!
The more CO₂ that is emitted the more the temperature rises, & the effect of CO₂ is essentially permanent.
The carbon budget can be defined at the point CO₂ emissions go to zero, & temperature stabilises.
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The more CO₂ that is emitted the more the temperature rises, & the effect of CO₂ is essentially permanent.
The carbon budget can be defined at the point CO₂ emissions go to zero, & temperature stabilises.
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We have already emitted a lot of carbon, so the remaining carbon budget for:
• 1.5°C is tiny (it is as good as gone)
• 2°C is tight (2.5x larger than 1.5°C)
• >4°C is huge, 2x more than the CO₂ emitted historically
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• 1.5°C is tiny (it is as good as gone)
• 2°C is tight (2.5x larger than 1.5°C)
• >4°C is huge, 2x more than the CO₂ emitted historically
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Using carbon budget thinking...
• 1.5°C is near impossible (budget is almost gone)
• 2.5°C is not so hard with raised ambition (& net-zero)
• 3°C may already be locked in with current ambition
• 4°C is hard, as it is a lot of carbon to burn
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• 1.5°C is near impossible (budget is almost gone)
• 2.5°C is not so hard with raised ambition (& net-zero)
• 3°C may already be locked in with current ambition
• 4°C is hard, as it is a lot of carbon to burn
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This opens itself to a risk framing:
• Likely pathway ~3°C
• Physical risks: assess higher outcomes (>3°C)
• Transition risks: assess more rapid mitigation (<3°C)
• Desired outcome is <2°C
cicero.oslo.no/en/posts/news/…
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• Likely pathway ~3°C
• Physical risks: assess higher outcomes (>3°C)
• Transition risks: assess more rapid mitigation (<3°C)
• Desired outcome is <2°C
cicero.oslo.no/en/posts/news/…
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Can illustrate the risk perspective using pathways:
• Black line is approximately a current policy pathway
• Transition risk (left): More rapid transition (tech, policy, social)
• Physical risk (right): Worsening climate impacts
cicero.oslo.no/en/posts/news/…
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• Black line is approximately a current policy pathway
• Transition risk (left): More rapid transition (tech, policy, social)
• Physical risk (right): Worsening climate impacts
cicero.oslo.no/en/posts/news/…
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Note that 2C should be 25% by 2030, not 75%...
And get some more info here...
