Global climate change Topic 7 Part 2

The oceans and the carbon cycle

Carbon and marine organisms Carbonate is used by MANY marine organisms to build themselves: –Corals –Shelled molluscs –Coccolithophores –Diatoms

Ocean acidification Since the Industrial Revolution, the ocean's have absorbed approx. 50% of the CO 2 from fossil fuel burning. Overall, ocean acidity has increased by 30%. When CO 2 dissolves in seawater, it forms carbonic acid. CO 2 + H 2 O ↔ H 2 CO 3 (carbonic acid) Some of the carbonic acid dissociates in water, releasing hydrogen ions and bicarbonate. H 2 CO 3 ↔ H + + HCO 3 - Two effects: Some H + stay in the ocean water decreasing the overall pH of the ocean. Some H + combine with carbonate ions to create bicarbonate. H + + CO 3 2- ↔ HCO 3 -

Effects of ocean acidification Decrease in hard coral skeleton growth –Reduced resiliency of corals to disease and temperature changes Plankton and other animals lose ability to make protective shells Reduction in plankton = reduction in rest of food chain. © Stephanie Talmage

Coral reefs: another canary Optimal conditions occur in a narrow range: –20-30° C –Salinity ppt –Moderate UV levels –Low turbidity Lethal conditions: –Above 30° C –Very high or very low salinity –Heavy siltation

Bleaching

Global change: the Big Picture impacts and consequences Impacts: –Sea level rise –Melting of permafrost –Extreme weather (floods and droughts) –Warmer sea surface temperatures –Ocean acidification Consequences: –Biodiversity loss –Potential changes in ocean currents –Population displacement –Spread of tropical diseases –Some places will benefit, others will suffer

Solutions Mitigation –Reduction in greenhouse gas emissions to slow global change Adaptation –Come up with ways to deal with the negative impacts and reduce their harmful effects Both are ongoing, to a point Two schools of thought: –"wait and see": economists, last US administration, very few scientists –"act now": many scientists, economists, political leaders (prominently European Union and island nations) –Precautionary principle

Solutions Mitigation will have to occur on many levels to be effective: –Personal –Local –National –International

Possibilities Carbon sequestration –Capturing and storing CO 2 emissions Pumping deep into the ocean or filling empty oil reservoirs/coal seams Problems: expensive and currently inefficient Putting in the ocean may further alter the carbon cycle and ocean chemistry –Soil sequestration and no-till cultivation Problem: soils may give up carbon dioxide as temps warm up and decomposition increases –Planting forests Generally a good idea! But must be paired with lower deforestation rates.

International actions IPCC (Intergovernmental Panel on Climate Change) 1988, has put out many reports Kyoto Protocol –1997 (to be implemented in 2005) –38 developed countries signed on, not including US and Australia –By countries signed on –Requires the participants to reduce greenhouse gas emissions (CO 2, methane, N 2 O) to 5.2% below their 1990 levels by 2012 –Allows for emissions trading between countries and banking of credits

How Would You Vote? Should the United States participate in the Kyoto Protocol? 1.No. Americans spend enough on environmental cleanup and should not take on the burden of this treaty. 2.Yes. We should participate, but only if India, China, and all other nations fairly participate. 3.Yes. As a leading emitter of greenhouse gases, the U.S. should set an example for other nations.

Math practice 1.Determine the net change in atmospheric CO 2 concentration between 150,000 years ago and 130,000 years ago. 2.Calculate the ratio of the change in mean global temperature to the change in atmospheric CO 2 concentration between 150,000 years ago and 130,000 years ago.