Geo-Engineering Challenges to Marine Biodiversity

1. Geo-Engineering Challenges to Marine Biodiversity Richard Norris; SIO-UCSD

2. Direct human impacts(immediate effects) • Reduce biodiveristy & resilience • Both top-down and bottom-up impacts • Reduce mobility in face of climate change • Human environments typically: • species poor • short food-chains homogeneous • disturbed • have imported energy and nutrients Major challenges to Marine Biodiversity

3. Indirect human impacts(long-range impacts) due to Global change • Acidification • Stratification • Altered PPT patterns • Storm and sea-level impacts on coasts Major challenges to Marine Biodiversity

4. Consider the nature of impacts that would exist under a business-as-usual scenario Partial solutions may be preferable to no solution …But there are worries that partial solutions will sap political will to act Keeping Perspective

5. Albedo enhancement • Reflectors, Cloud production and Ground-based albedo enhancement • Land-based Carbon Sequestration • CO2 into oil wells, saline aquifers, Enhanced weathering • Ocean-based Carbon Sequestration • Ocean dumping of CO2, Biochar, Nutrient fertilization, Enhanced weathering Three types of Geo-engineering

6. Methods that change the chemistry of systems • These typically address the acidification issue as well as climate change • Those that do not…. • Usually only deal with temperature Can also think about just two categories

7. Common themes—no reduction of: • CO2absorption in ocean • acidification • environmental loading of other waste products of fossil fuel burning—NOx, SOx, trace metals (many of them heavy metals) • NOx already a problem in coastal water ways • Carbon-particulates (ash) Albedo-enhancing Geo-engineering Consequences

8. Changes albedo at the top of the atmosphere • Because these are in space, the main impacts on ecosystems come from potential changes in weather systems, ppt, land-sea contrasts, and continued acidification • Diminished UV may also affect composition of surface ocean phytoplankton Reflectors in space

9. Impacts from changes in weather • Severity related to shifting ‘natural’ processes into new frequency, geographic position, or stable states. • Mucking around with the PDO, NAO and other multi-decadal cycles • e.g. Mantua et al. 1997, Bull Am, Met. Soc • Of course, all these happen anyway with global change. Reflectors in space

10. Increasing cloudiness: • Changes community structure toward low-light intensity communities with potential impacts on export production; • Clouds may affect air-sea temperature contrast • Storm intensity& evaporation weakened (Mahmud 2009 Singapore J Trop. Geography) • Implications for nutrient exchange between thermocline and surface. • Create a permanent, local el-Niño? Shepard et al. 2009 after Latham et al, 2008 Cloud Seeding with Salt Spray

11. Water removal could affect: • Larval abundance and viability (like desalination plants) • Permanent installations • Act as giant open-ocean habitats (Fish Aggregation Devices) for highly-migratory fishes and marine mammals Some other impacts of cloud ‘whitening’

12. Acid rain • Sure, but the ocean is big and relatively well mixed • More of a problem for poorly buffered terrestrial systems • BUT, deposition on snow or ice could create a runoff acid pulse to coastal waters—problematic for Arctic, Antarctic… SO2 addition to atmosphere www.swisseduc.ch/glaciers

13. Ozone destruction • increases UV influence in surface ocean • but ocean absorbs UV efficiently • Experiments show some diatoms (Pseudo-nitzschia) do well in high UV waters (Mengelt & Prezelin (2005) Mar-Ecol. Prog Series) • UV also reduced overall phytoplankton production (Llabres & Agusti 2010 Aquatic Microb. Bio; Finkel et al. 2010; J. Plank. Res) • Could be a problem for seabirds, seal colonies (walrus, fir seals, elephant seals…) SO2 addition to atmosphere

14. These seem unlikely to have a major impact on marine communities • Unless they alter weather • Water runoff • Sediment and nutrient transport by wind, streams or dissolved ground water flows. Ground-based albedo enhancement

15. Major impacts from land-based enhanced weathering: • Could change the flows of dissolved compounds (like bicarbonate ion) and cations into ocean water. • Waste streams are likely to be concentrated • Have many of the same impacts as saline outfall from desalination plants • Could offset ocean acidification • But this depends upon where outfall is delivered • Local alkalinity spikes might contribute to ‘whitings’ Ocean-based C-Sequestration

16. Peridotite is not a completely benign substance • due to imbalances in Mg/Ca ratios • High concentrations of Ni, Co, Cr; low Mo • A “serpentine barrens” of the sea? Trace metals are the problem US Forest Service

17. Dumping effluent from enhanced weathering like other waste streams • Tend to produce reduced biodiversity & short food chains Enhanced Weathering

18. Consumption of other bio-limiting nutrients • Causes Fe-fertilization to ‘rob’ downstream communities of nutrients • Shortening food chains • Changes in marine community structure depending upon type of phytoplankton production • increased primary production would likely shorten food chains and reduce biodiversity. Ocean-based Carbon Sequestration

19. O2consumption • Impacts of doubling c-flux to the sea floor on benthic communities • Ocean O2(Keeling et al. 2010, Ann Rev Mar. Sci; Shaffer et al. 2009 Nature Geosci) • Models already predict up to ~60% volume of ocean affected by ocean hypoxia in coming millennia • A return to the Cretaceous? Nutrient Fertilization

20. Biochar storage in the ocean • Potential habitat for wood-loving taxa; • if stored as wood or biomass has short lifecycle owing to ship worms (>> Century) Ocean-based Carbon Sequestration askNature.org

21. CO2 removal either by political will or technology deals with most problems • CO2 dumping in ocean could be problematic if not neutralized by carbonate or buried. • From a biodiversity perspective, solutions that leave acidification in place are the most dangerous (e.g. albedo enhancement) • But, in short-term, direct human impacts are the major threat Geo-engineering-final thoughts