Carbon dioxide has become the major concern in the world of science in the past 50 years. We have become more concerned with how our carelessness of not being environmentally friendly will impact our children in years to come. This may seem initially like an atmospheric problem, but many of the changes yet to come start in the ocean especially with our emissions on constant rise, just in 2010 our emissions rose 5.9%.
Before I introduce El Niño and its impact, let’s first have a glimpse of Walker Circulation. (Figure 1).
Figure 1. Walker Circulation (http://www.youtube.com/watch?v=f-r82_HRfNw)
When an El Niño (the boy in Spanish) event happens, the normal location of Indonesian Low continuously moves eastward, which eventually reverses the high-low pressure relation. The eastward moving Indonesian Low weakens the strength of the southeastern trade wind and the upwelling at southeastern Pacific.
Since 1751 to 2004 the ocean’s pH has been estimated to decrease from approximately 8.25 to 8.14. With the combustion of fossil fuels it leads to a great increase of CO2 in the atmosphere, where the oceans have absorbed some of the CO2. The effects that acidification of the ocean has on the ecosystem are evident in the slower growth of coral, oyster larvae suffering, and plankton with calcareous skeletons losing mass.
It may be hard to believe that melting of ice sheets and glaciers hundreds if not thousands of miles north/south of your home would have any effect on you, but it has been shown that the polar ice sheets are crucial controllers of the global climate (here is a link to a recently observed climate impact as well as another discussing observations on the accelerating ice melt) and the drivers of oceanographic circulation (shown in fig.
A coral reef is a diverse ecosystem that consists of a collection of biological communities of calcifying organisms. These ecosystems are currently being threatened by the rising acidification of earth’s oceans. Ocean acidification is caused by pH reductions and changes in fundamental chemical balances (Kleypas, 2009). The corals have a hard calcium carbonate skeleton that is most directly affected by ocean acidification.