Impacts of Global Warming on the Ocean and Coral Reefs

1. Impacts of Global Warming on the Ocean and Coral Reefs Emily Underriner ChE 359 November 24, 2008

2. Agenda • Global Warming and Climate Change • The Ocean and Coral Reefs • Impacts • Temperature • Acidity • The Future Challenges

3. Global Warming • Prior to industrial revolution: 280 ppm • Current day: 387 ppm • “Greenhouse” effect • By 2100, CO2 levels to double pre-industrial revolution • Loss of environmental biodiversity, disrupt ecosystem processes, and reduce ecological goods and services

4. Importance of the Ocean • Yearly global economic value of $21 trillion • The largest sink/reservoir of atmospheric CO2 emissions • Contains 50 times the amount of carbon in the atmosphere and 10 times more carbon than is held by soil and plants • CO2 uptake has not been without negative consequences

5. CoralReefs • Coral reefs: corals, coralline algae, fish, others • Corals: small animals • Begin as larva, attach to hard surface • Build coral skeleton via reaction of Ca and CO2 to make CaCO3, or limestone • Symbiotic relationship with yellow-brown algae, zooxanthellae • Provide coral with nutrients • Coral provides protection and access to light http://oceanworld.tamu.edu/students/coral/coral5.htm

6. Coral Reefs Source: wwf.org Source: myclimatechange.net

7. Importance of CoralReefs • Among the most diverse and productive ecosystems on earth (tropical rainforests of the sea) • Support 25% of all known aquatic wildlife species, over 4,000 species of fish, 700 species of coral, and thousands of others • Provide: food, supply economic income via fishing and tourism, shoreline protection, integral ocean sink for atmospheric carbon dioxide • Supply $375 billion in ecosystem goods and services to the global economy each year

8. Impacts on the Ocean • Temperature Rise • Air has higher thermal heat capacity than water • Since the 1950s, average temperature increase of 0.31 °C in top 300 meters of water • Acidification • Since the 1900s, 30% increase in H+ in ocean

9. Temperature Impact on CoralReefs • Coral reefs very sensitive to changes in the ocean’s temperature • Generally require T between 25°C and 29°C • T change of only a few degrees above the long-term average can cause coral to die • “Bleaching” – loss of zooxanthellae • Over 60% of the earth’s coral reefs will be lost by the next 25 years

10. Coral Reef Bleaching • Between 1979 and 1990, out of 105 mass coral moralities, 60 coral reef bleaching events were reported, compared with only three bleaching events among 63 mass coral moralities for the preceding 103 years Source: http://www.marinebiology.org/coralbleaching.htm Source: Texas A&M University, Coral Reefs

11. Acidification • Increasing ocean CO2 concentration • Historically: pH of 8.2 • Since early 1900s, pH drop by 0.1 units, estimate a drop in seawater pH by 0.5 units by 2100 • CO2 reacts with water to form carbonic acid (H2CO3) • Increases carbonate (HCO3−) and H+ in the ocean surface water (reducing pH), decreases bicarbonate (CO32−) • Coral reef organisms rely on the concentration of bicarbonate to form hard skeletons • Predict threshold to be met around 2050

12. The Future • More research on coral reef impacts • Increasing carbon concentration is dangerous • GHG and carbon mitigation • Reduce emissions • Sequestration • Impacts on entire ocean ecosystem difficult to predict

13. Thank you!