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Rising Temperatures And Ocean Acidification: The Effects Of Climate Change On Our Oceans


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Posted by on December 12, 2006 at 05:01:20:

Gone is the uncertainty of whether climate change will happen. The past few months have resulted in a large influx of international reports assessing the current and potential effects of climate change on our planet and oceans. The reports utilize past and current data to model predictions for the future.

While each report is structured differently and uses slightly different data, general themes keep emerging in relation to climate change effects on marine ecosystems and oceanic functioning: rising sea surface temperatures and ocean acidification. But what does that all really mean? How will it affect our corner of the ocean?

The Earth’s climate is changing. Over the past few centuries the average ocean temperature has risen roughly 3.5° F. While the increase in global temperatures is hard to dispute, the consequences of these rising temperatures are often difficult to specify. Research continues to demonstrate that rising sea surface temperatures significantly effects weather patterns and marine organismal distribution. Global weather patterns determine storm frequency and intensity. Rising temperatures correlate with recent increases in severe storms. But storms are not the only problem related to rising temperatures. The increase in water temperatures also effects where specific marine organisms can survive. As sea temperatures rise, the distribution of warm water organisms expands to include more northern regions, further stressing cold water organisms with increased competition. Planktonic organisms and larval stages of other marine organisms are most affected by rising temperatures. Plankton make up the base of oceanic food webs and are often highly sensitive to environmental variables. Major changes to planktonic distribution can result in drastic alterations to marine ecosystems at all levels of the food chain.

Another consequence consistently presented by climate change reports is ocean acidification. Rapid increases in CO2 emissions are a result of various man-made processes in the industrial age. Carbonic acid results when carbon dioxide interacts with surface water and dissolves. As rising surface temperatures lead to a decline in the number of phytoplankton, which are the small plants in the oceans that absorb carbon dioxide to provide more than 50% of the oxygen that we breath, more carbon dioxide will dissolve to make carbonic acid. The more carbonic acid formed the lower the pH will drop towards more acidic conditions. Average oceanic pH has already dropped from 8.25 to 8.14 since 1751. As the oceans become more acidic due to carbonic acid, organisms that rely on sequestering carbon from seawater are unable to access the carbon. Calciferous organisms, such as plankton and corals, use carbon to form necessary bodily compartments for structure and protection. As these species strength and protection are altered, species will no longer be able to survive, which will also alter the marine food web. Again the organisms predicted to be affected the most are at the foundation of the marine food web.

The facts of increasing temperatures, dropping ocean pH, increasing ranges of warm water plankton, and increasing storm intensity are now irrefutable. Yet it is difficult for scientists to look at all of the data and determine cause and effect relationships between these factors to predict future realities. Regardless, multiple studies and climate models now predict large alterations to marine ecosystems and oceanic functioning from the bottom up due to cascading responses to climate change.

A recent report from the Marine Climate Change Impact Partnership (MCCIP), based in the United Kingdom, attempts to bring many ocean stakeholders and experts together to assess the current data and make predictions for the future. The organization publishes an “Annual Report Card” summarizing the data, predictions, and degree of certainty of the scientists about each issue. The MCCIP recognizes that predicting the future of a delicate ecosystem requires a delicate balance between research and modeling. The top two outcomes that the committee of scientists were most certain about were rising sea surface temperatures and ocean acidification. For more information about the MCCIP report visit www.mccip.org.uk/arc/section1.html. Additionally, the National Public Radio recently highlighted the issues surrounding rising surface temperatures and ocean acidification during Morning Edition on 7 December 2006, available at: www.npr.org/templates/story/story.php?storyId=6591611.



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