Concerned about the plankton decline, but not so sure how consistent this decline is

Out of the three articles I read, I found Richard Black's BBC News Article, "Plankton decline across oceans as waters warm" to be the the most accurate and unbiased story. The story that is being told for the 2010 article I read is about how plankton are declining across multiple oceans due to warmer waters. The next story I read, which was from 2013, was about how the algorithm found missing phytoplankton in the Southern Ocean. My biggest concern about phytoplankton populations after reading all of the articles was the decline in the amounts of phytoplankton. This is because of warmer waters and less absorption of carbon dioxide. Less absorption of carbon dioxide makes the air less safe, and with less plankton in the water, photosynthesis will occur less. Phytoplankton populations are measured by using an algorithm and using satellite measurements. The conflict in these articles is the disappearance of plankton, and the disappearance causes the decline of oxygen in the air for humans to breathe. After reading the three articles I chose, I am concerned with the plankton decline, but the studies shared in the articles did not seem too sure about how consistent the decline is.

http://en.wikipedia.org/wiki/Phytoplankton