[ 85 ] Earth and Space Science GED ® TEST SCIENCE FLASH REVIEW • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Refer to the following passage to answer the next five questions. Gas exchange between the air and oceans is primarily controlled by the air-sea difference in gas concentrations. It is not unusual for there to be differences in the carbon dioxide (CO 2 ) levels between air and ocean because it takes about a year for surface ocean CO 2 to equilibrate with the atmospheric CO 2 . Oceans hold large reservoirs of carbon that can be exchanged with the air because CO 2 reacts with water to form carbonic acid. Ocean acidification is a result of increasing atmospheric carbon dioxide levels interacting with the surface oceans. When increasing CO 2 levels change the global climate, the temperature changes impact ocean circulation; in turn, ocean circulation impacts ocean CO 2 uptake. Ocean acidification impacts marine ecosystems, which can also result in changes in the air-sea CO 2 exchange. What is the main topic of this passage? A. mechanisms of ocean circulation and its effects B. ocean acidification and its consequences C. ocean CO 2 absorption and its consequences D. oceans and global climate change When carbon dioxide is absorbed by the ocean, it becomes ____________.