Mitigation

Based on current knowledge of marine impacts, Turley et al. (2010) recommend that 500 ppm atmospheric CO2 should be avoided and that a threshold of 450 ppm CO2 be adopted to ensure no largescale risk to marine organisms and ecosystems. Most scientists agree that the smaller the CO2 buildup the less the likelihood of dire impacts (Broecker 1997; Raven et al. 2005). But the demand for cheap fossil energy continues to grow. Unfortunately, no viable and acceptable option to fossil fuels has yet been devised (Broecker 1997). To curtail CO2 emissions, it is proposed to plant forests, use alternative energy sources-such as wind, solar, and nuclear-or a combination of national and multinational cap-and-trade systems (Stavins 2009). Companies around the world would be issued rights by their governments to produce carbon, which they could buy and sell on an open market. If they wanted to produce more carbon, they could buy another company=s rights. If they produced less carbon than they needed, they could buy and sell on an open market. For example, the U.S. and China-two major emitters of CO2 (Table 8.1)—are currently involved in negotiations about climate policy. If the two nations enter into a bilateral agreement, other major nations may join. From there, developing nations could join giving them targets to reduce emissions without stifl ing growth. With the right incentives, developing countries will adopt less carbon-intensive growth paths (Stavins 2009). If the risk of irreversible damage arising from ocean acidifi cation is to be avoided, particularly in the Southern Ocean, the cumulative future human derived emissions to the atmosphere must be considerably less than 900 Gt C by the

et al. 2005), but this need to be verifi ed.