Why is Climate Engineering on the Agenda and What Does It Offer?

Masa SugiyamaAssociate Professor Institute for Future Initiatives The University of Tokyo

IPCC WG3 AR6 Ch12 lead author

masahiro_sugiyama@alum.mit.edu 1

Nov. 1, 2019

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https://news.yahoo.com/paris-hits-record-42-4c-temperature-weather-151001981.html

https://www.nikkei.com/article/DGXMZO50952990T11C19A0MM8000/

Paris Agreement and climate engineering

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Climate engineering: deliberate large-scale intervention in the Earth’s climate system

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Climate engineering or geoengineering or climate intervention

Solar radiation modification (SRM) or solar geoengineering

Carbon dioxide removal (CDR) or negative emissions technology (NET)

Source: The Keith Group, Harvard University

Source: Swissinfo.ch

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The Paris climate targets require “far-reaching and unprecedented changes in all aspects of society”

https://www.ipcc.ch/site/assets/uploads/2018/11/pr_181008_P48_spm_en.pdf6

To achieve the 1.5-degree target, the world must embark on immediate, unprecedented cuts

7IPCC (2018)

To achieve the 1.5-degree target, the world must embark on immediate, unprecedented cuts• Or the world must remove CO2 from the atmosphere on a very large scale

8IPCC (2018)

If emissions cuts / CDR fails, or if temperature overshoots, solar geoengineering could be used to reduce climate risks

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IPCC (2018) SR15 Ch4

Why do we have to discuss CDR and SRM? They are (potentially) very useful but come with significant side effects

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Multi-dimensional evaluation of various climate engineering options

(Oschlies &Klepper 2017)(Update of Royal Society 2009)

Risks of large-scale CDR

India land area

~ 3M km^2 = 300 Mha

Current global primary energy = ~ 500EJ/yr

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Smith et al. (2016) https://doi.org/10.1038/nclimate2870

Risks of large-scale SRMTermination shock, precipitation, ozone, etc.Brovkin et al. (2008, Climatic Change)

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Impacts of CDR & SRM are highly context-dependent

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Significant side effects

Global warming

100% cancelled by climate engineering

Global warming

50% cancelled byclimate engineering

Less side effects

Irvine et al. (2019)See also Keith and MacMartin (2015)Sugiyama et al. (2018),

Unilateral deployment is possible (at least theoretically)

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Moriyama, Sugiyama et al. (2016)

Asia-Pacific should engageA significant contribution on the modeling side (presentations by Dr. Lenton and Prof. Moore) , but more is required on the social science side and governance (Dr. Gosh)

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Why is Climate Engineering on the Agenda and �What Does It Offer?スライド番号 2Paris Agreement and climate engineeringClimate engineering: �deliberate large-scale intervention in the Earth’s climate system スライド番号 5The Paris climate targets require �“far-reaching and unprecedented changes in all aspects of society”To achieve the 1.5-degree target, �the world must embark on immediate, unprecedented cutsTo achieve the 1.5-degree target, �the world must embark on immediate, unprecedented cutsIf emissions cuts / CDR fails, or if temperature overshoots, �solar geoengineering could be used to reduce climate risksWhy do we have to discuss CDR and SRM? Multi-dimensional evaluation of various climate engineering options��(Oschlies & Klepper 2017)�(Update of �Royal Society 2009)Risks of �large-scale CDRRisks of large-scale SRM�Termination shock, precipitation, ozone, etc.Impacts of CDR & SRM are highly context-dependent Unilateral deployment is possible �(at least theoretically)Asia-Pacific should engageスライド番号 17