Solar geoengineering: Implications for the ocean, marine ecosystems and dependent human communities

William W. L. Cheung Professor and Director The University of British Columbia

@ubcoceans @coru_ubc

Email: [email protected] INSTITUTE FOR THE OCEANS AND FISHERIES

• Interdisciplinary research to support healthy Oceanography and sustainable ocean and aquatic systems , ecology and biology • Oceans and Fisheries graduate program (OCF)

• Home of a diverse group of postdoctoral To lead the way to fellows and research associates healthy and sustainable marine and freshwater Data Human, social systems through science, • Collaborations and partnerships across and economic excellent research, scenarios & academic, governmental, public and private dimensions inspirational education, modelling sectors and stake-/knowledge- holders from and innovative societal local to global engagement.

Policy and sustainability

2 Acknowledgement

Committee members Chris Field, Stanford University [Chair] William Cheung, the University of British Columbia, Canada Lisa Dilling, University of Colorado Peter Frumhoff, Union of Concerned Scientists Hank Greely, Stanford Law School Marion Hourdequin, Colorado College Jim Hurrell, Colorado State University Andrew Light, George Mason University [until Jan. 2021] Albert Lin, Univ. California, Davis School of Law Douglas MacMartin, Cornell University Robert McHenry, Palo Alto Research Center Juan Moreno-Cruz, University of Waterloo Katharine Ricke, University of California, San Diego Lynn Russell, Scripps Institution of Oceanography Ambuj Sagar, Indian Institute of Technology, Delhi Paul Wennberg, CA Institute of Technology Outlines

1. Changing climate and ocean – reasons for concerns;

1. Solar geoengineering and marine ecosystems – risks and knowledge gap;

1. Research agenda. Changing climate and ocean – reasons for concerns effects and its impacts are wide-spread in the world’s oceans

Figure 2 SPM; IPCC SROCC (2019) Climate change effects and its impacts are wide-spread in the world’s oceans

Figure 2 SPM; IPCC SROCC (2019) Climate change effects and its impacts are wide-spread in the world’s oceans

Figure 2 SPM; IPCC SROCC (2019) Ocean changes with carbon emissions

Sea surface • Ocean warming has more than temperature doubled;

Ocean acidification • Marine heatwaves have doubled in frequency; Marine heatwaves • is intensifying as more CO , is Oxygen content 2 absorbed;

Summer sea ice • Oxygen minimum zones Ocean heat content expanded by 3-8%;

• Arctic sea ice will disappear once every three years under 2 oC global warming. Sea level rise (by 2300)

IPCC (2019) SROCC SPM Projected global and regional impacts on marine ecosystems and fisheries

Net primary production Provide carbon and energy for foodweb Total animal biomass Biomass of organisms in the upper part of the foodweb

Maximum fisheries catch Changing ocean conditions potential Proxy of maximum sustainable yield

IPCC (2019) SROCC SPM Sensitive ecosystems are already at risk now

IPCC (2019) SROCC SPM Heatwaves are already impacting ecosystems, fish stocks, fisheries and fishers Solar geoengineering (SG) and marine ecosystems – risks and knowledge gap Large knowledge gap in SG: ecosystem and ecology

General observations from the literature review:

• Lack of specificity on the details of how an intervention is implemented—that is, the specific approach used, how that approach is deployed, and how much cooling is pursued;

• Many of these details will be highly contingent on the socioeconomic and geopolitical background conditions and decision-making framework in implementations;

• Lack of robust research scenarios for exploring the complex dynamics of social-ecological systems;

• The above is important in understanding the magnitude and spatial/temporal patterns of many impacts.

Source: National Academies of Sciences, Engineering, Medicine (2021) Ocean systems in particular …

Source: NASEM (2021) Solar-geoengineering and implications for the ocean

Example of related risks • Coral bleaching • Changes in ocean productivity • Biodiversity and related ecological functions • Loss of fisheries and aquaculture production potential • Cascade of societal/economic impacts resulting from the changes above

Source: National Academies of Sciences, Engineering, Medicine (2021) Coral bleaching Severity of coral bleaching relates to warming and cloud cover (light intensity) Degree Heating Weeks Heating Degree Cloud cover anomalies Cloud cover

Source: Gonzalez-Espinosa and Donner (2021) Global Change Biology Projected effects of SG on coral reefs

Low risk • Effects of different SG interventions on cloud cover, ozone, UV and their impacts on coral bleaching are unclear; High risk • Impacts from ocean acidification largely not mitigated. Reduction in by SG by forcing in radiative Reduction

Source: NASEM (2021) adapted from Irvine et al. (2018) Ocean productivity Effects of solar geoengineering on temperature

• SG (mainly Stratospheric Aerosol Injection) may alter the magnitude of warming, and seasonal cycle and amplitude, and reduce the risk of temperature extremes with large regional differences;

• Termination of intervention may lead to rapid warming, with possibility of non- linear ecological responses such as shifts in biogeography and trophodynamics of marine ecosystem.

Source: Tilmes et al. (2020) Effects on net primary production (NPP)

• Global ocean modeling experiments suggest that SG interventions could lead to a global decrease in ocean NPP relative to scenarios without SG interventions;

• Driven by ocean circulation, incoming radiation, temperature, availability of nutrients, and phytoplankton biomass;

• Spatial variations differ between types of interventions;

Source: Tilmes et al. (2020) • In general, CMIP6 Earth system models have low agreement in NPP projections. Projected global and regional impacts on marine ecosystems and fisheries

Net primary production Provide carbon and energy for foodweb Total animal biomass Biomass of organisms in the upper part of the foodweb

SG Intervention Maximum fisheries catch potential Proxy of maximum sustainable yield

IPCC (2019) SROCC SPM Expert-based assessment on effectiveness of SG interventions as climate solutions for the ocean

• Potentially high effectiveness to moderate ocean warming, moderate for sea level rise and low for ocean acidification and reduce their impacts;

• High potential negative consequences, and low co-benefits;

• Low global governability and cost effectiveness;

• High uncertainty (lack of information). Suggested areas for research: ocean responses

• Use Earth system models to establish better estimates of the uncertainties in regional climate responses to SG • Model processes should be investigated individually and tracked so that specific deficiencies and inter-model differences can be identified and improved.

• Develop more realistic Earth system model scenarios that explore the range of possible SG strategies and explore how SG forcing differs from other anthropogenic climate forcing. • Utility of large ensembles to quantitatively document the irreducible uncertainty in climate and ocean response arising from unforced natural (or internal) variability and to frame projected responses in terms of probabilities.

• Improving and validating Earth system models. • Observations for validating aerosol/cloud distribution in key regions and to better characterizing stratospheric composition, and CPTs to help address modeling needs specific to SG strategies. • Replace problematic subgrid-scale parameterizations with explicit processes.

Source: National Academies of Sciences, Engineering, Medicine (2021) Suggested areas for research: Hazards and risks

• Advance methodologies for how to assess the human/ecosystem impacts that can cascade from primary climate impacts;

• Explore impacts at sufficient model resolution to inform regional/local-scale decisions;

• Assess impacts on a broad range of natural and human-managed ecosystems, social and economic outcomes; assess distribution of benefits and risks;

• Track changes in direct and diffuse radiation, for assessing photosynthesis changes in crops, natural ecosystems, phytoplankton;

• Support long-term observations including co-located monitoring of multiple variables;

• Study dose/response effects of proposed SG aerosol chemical components on ecosystem/human health.

Source: National Academies of Sciences, Engineering, Medicine (2021) Suggested areas for research: Monitoring and attribution

• Attributing SG impacts in the ocean will be very challenging, because many impacts will evolve over long timescales; difficult to separate from natural variability and other confounding human drivers;

Some critical steps forward: ● Assess what variables would provide the earliest/highest signal-to-noise signals to aid attribution; explore approaches to improve the signal-to-noise in such observables; ● Advance long-term monitoring. Some concluding thoughts

The research agenda should be The recommended research governance pursued as an integrated whole. and engagement efforts will enable the Pursuing individual elements in isolation program to proceed in a societally will undermine program goals and responsive and acceptable manner. outcomes. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance

Thank you