In his 222-page encyclical, Pope Francis warned about (1) the polar plight, (2) sea level rise, (3) ocean-bound water pollution, (4) ocean acidification, (5) overfishing and (6) loss of marine biodiversity. It's Not Just Climate — Pope Francis Is Also Warning About The Health Of Our Oceans
by Elise Shulman
With the release of his encyclical "Laudato Si" on Thursday, Pope Francis made headlines for recognizing the threat of human-caused climate change.
But the encyclical also called attention to the world's oceans, affirming just how vital they are to "our common home." In Laudato Si, Francis talked about the unique threats marine environments face in a planet changed by humanity.
Below are six warnings from the Pope about the health of our oceans. Quotes from the encyclical are shown in italics, along with their corresponding passage number.
The polar plight
"The melting in the polar ice caps and in high altitude plains can lead to the dangerous release of methane gas, while the decomposition of frozen organic material can further increase the emission of carbon dioxide." 
Global warming is happening at a greater degree at Earth's poles in a dangerous positive feedback cycle advanced by the high reflectivity of ice. As white, energy-reflecting snow and ice melts, it becomes darker, energy-absorbing water and land. If left uncurbed, warming will melt polar permafrost, unlocking frozen, ancient carbon and accelerating climate change.
Sea level rise
"A rise in the sea level... can create extremely serious situations, if we consider that a quarter of the world's population lives on the coast or nearby, and that the majority of our megacities are situated in coastal areas." 
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