A. Ocean acidification is a significant and harmful consequence of excess carbon dioxide (CO2) in the atmosphere, often referred to as "the other CO2 problem" alongside global warming. When CO2 is absorbed by seawater, a series of chemical reactions occur that increase the concentration of hydrogen ions, making the seawater more acidic and reducing the concentration of carbonate ions. This change in ocean chemistry has profound implications for marine life and ecosystems.
B. The primary impact of ocean acidification is on marine organisms that build shells or skeletons out of calcium carbonate, a process called calcification. This includes corals, shellfish like oysters and clams, and many species of plankton that form the base of the marine food web. As the water becomes more acidic, carbonate ions become less available, making it more difficult and energetically costly for these organisms to build and maintain their shells. In highly acidic conditions, existing shells can even begin to dissolve.
C. The consequences of this are far-reaching. The decline of coral reefs, which are particularly vulnerable, would lead to a catastrophic loss of biodiversity, as reefs provide essential habitat for about 25% of all marine species. The impact on plankton could have a ripple effect up the entire marine food chain, affecting the fish, birds, and marine mammals that depend on them for food. The shellfish industry, a vital source of food and income for many coastal communities, is also under direct threat.
D. While the chemistry of ocean acidification is well understood, its full ecological impacts are still an area of active research. The only long-term solution to halt ocean acidification is to significantly reduce global CO2 emissions by transitioning away from fossil fuels. In the shorter term, strategies such as protecting marine ecosystems from other stressors like pollution and overfishing can help to build their resilience. Addressing this silent crisis is essential for the health of our oceans and the planet as a whole.
IELTS Practice Tests Practice Test / Part 1 #155
IELTS Practice Tests Practice Test / Part 1 #208
