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

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Presentation on theme: "{ Geo-Engineering Challenges to Marine Biodiversity Richard Norris; SIO-UCSD."— Presentation transcript:

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

2 Major challenges to Marine Biodiversity 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

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

4 Keeping Perspective 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

5 Three types of Geo-engineering Albedo enhancement Reflectors, Cloud production and Ground-based albedo enhancement Land-based Carbon Sequestration CO 2 into oil wells, saline aquifers, Enhanced weathering Ocean-based Carbon Sequestration Ocean dumping of CO 2, Biochar, Nutrient fertilization, Enhanced weathering

6 Can also think about just two categories 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

7 Albedo-enhancing Geo- engineering Consequences Common themes—no reduction of: CO 2 absorption in ocean acidification environmental loading of other waste products of fossil fuel burning—NO x, SO x, trace metals (many of them heavy metals) NO x already a problem in coastal water ways Carbon-particulates (ash)

8 Reflectors in space 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

9 Reflectors in space 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.

10 Cloud Seeding with Salt Spray 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

11 Some other impacts of cloud ‘whitening’ 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

12 SO 2 addition to atmosphere 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…

13 SO 2 addition to atmosphere 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…)

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.

15 Ocean-based C-Sequestration 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’

16 Trace metals are the problem 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? US Forest Service

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

18 Ocean-based Carbon Sequestration 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.

19 Nutrient Fertilization O 2 consumption Impacts of doubling c-flux to the sea floor on benthic communities Ocean O 2 (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?

20 Ocean-based Carbon Sequestration 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)

21 Geo-engineering-final thoughts CO 2 removal either by political will or technology deals with most problems CO 2 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

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