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Projected changes to the tropical Pacific Ocean

Projected changes to the tropical Pacific Ocean. Based on. Outline. Projected temperatures and currents: surface and vertical structure Implications for oceanic nutrients Ocean acidification Sea-level rise. Sea surface temperature. Change in SST °C (2000-2100). 2000: 27.4°C

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Projected changes to the tropical Pacific Ocean

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  1. Projected changes to the tropical Pacific Ocean

  2. Based on.....

  3. Outline • Projected temperatures and currents: surface and vertical structure • Implications for oceanic nutrients • Ocean acidification • Sea-level rise

  4. Sea surface temperature Change in SST °C (2000-2100) • 2000: 27.4°C • 2035: 28.1°C (+0.7°C) • 2100: 29.9°C (+2.5°C) The ocean is a heat sink!

  5. Vertical structure and stratification } Warm, mixed-layer } Thermocline depth } Cold, deepocean

  6. Vertical structure and stratification } Warm, mixed-layer } Thermocline depth } Cold, deepocean

  7. Vertical structure and stratification • Most warmingoccurs at surface • Leads to increase in stratification

  8. Projected changes in vertical currents Less downwelling Less downwelling Less UPWELLING Less downwelling

  9. Implications for nutrients Warm, mixed-layer • Thermocline acts as a barrier • Limits the supply of nutrients Cold, deepocean Lownutrient High nutrient

  10. Implications for nutrients Warm, mixed-layer Cold, deepocean Lownutrient • Increased stratification makes it harder to bring nutrients upwards High nutrient

  11. Why is this important? • Nutrients support the food web for tuna

  12. Projected changes in major currents

  13. Eddies

  14. Nutrient supply by eddies • Eddies can temporarily lift nutrient-rich waters • Eddy activity is related to current strength

  15. Eddies and nutrients

  16. Convergence zone

  17. Importance of ENSO for fisheries • Skipjack tuna catch Source: Lehodey et al. (1997)

  18. Ocean acidification

  19. Projected acidification Saturation >4 = healthy conditions Saturation fallsbelow 3.3, causingproblems for corals Saturation decreases to 2.4

  20. Sea-level rise

  21. Summary • Increases in sea surface temperature • Stronger stratification • Nutrient reduced due to increase in stratification • Slowdown of equatorial currents and upwelling • Aragonite drops below critical levels • Sea level rise, > 1 m cannot be ruled out

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