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

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

Prior to industrial revolution: 280 ppm Current day: 387 ppm “Greenhouse” effect By 2100, CO 2 levels to double pre-industrial revolution Loss of environmental biodiversity, disrupt ecosystem processes, and reduce ecological goods and services Global Warming

Yearly global economic value of $21 trillion The largest sink/reservoir of atmospheric CO 2 emissions – Contains 50 times the amount of carbon in the atmosphere and 10 times more carbon than is held by soil and plants CO 2 uptake has not been without negative consequences Importance of the Ocean

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 CO 2 to make CaCO 3, or limestone Symbiotic relationship with yellow-brown algae, zooxanthellae – Provide coral with nutrients – Coral provides protection and access to light Coral Reefs

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

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 Importance of Coral Reefs

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 Impacts on the Ocean

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 Temperature Impact on Coral Reefs

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: Source: Texas A&M University, Coral Reefs Coral Reef Bleaching

Increasing ocean CO 2 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 CO 2 reacts with water to form carbonic acid (H 2 CO 3 ) – Increases carbonate (HCO 3 − ) and H + in the ocean surface water (reducing pH), decreases bicarbonate (CO 3 2− ) Coral reef organisms rely on the concentration of bicarbonate to form hard skeletons Predict threshold to be met around 2050 Acidification

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 The Future

Thank you!