climate change
/ˈklaɪmət tʃeɪndʒ/
noun
the phenomenon in which human overuse and processing of fossil fuels and other materials is releasing greenhouse gases into the atmosphere, contributing to rising temperatures and severe environmental repercussions in the ocean
ocean acidification
ocean acidification is the reduction in seawater pH due to an influx of hydrogen ions into the water through the introduction of excess carbonic acid into the ocean. the carbonate compensation depth—the lowest depth of the ocean at which calcium carbonate can be produced—is also being raised as the ocean continues to absorb more and more carbon dioxide. these problems pose a risk to countless marine species, such as oysters and coral, that need calcium carbonate to produce their protective shells and structures.
the ocean’s pH drop in the past two hundred years is equivalent to the changes experienced for the previous twenty million years.
rising sea levels
as climate change increases the temperature of the oceans, it causes seawater to expand and glaciers and ice sheets to melt, triggering a drastic rise in sea levels. this can lead to more severe, frequent storms and flooding, which threaten low-lying island nations and coastal regions of the world.
if the antarctic and greenland ice sheets were to entirely melt, sea levels would rise by approximately 66 meters.
climate regulation
the ocean’s process of thermohaline circulation—which is caused by water mass mixing due to salinity and temperature differences—plays a critical role in limiting global climate fluctuation. However, if water temperatures continue to rise, these changes could permanently shut down the ocean’s inherent ability to regulate temperatures around the world.
the slowdown of the gulf stream is already slowing down and causing more hurricanes and reducing marine organisms’ ability to survive in a wider range of temperatures.
estuarine damage
estuaries, the places where rivers feed into the sea, require a delicate balance in salinity and temperature to support their characteristically high levels of biodiversity. they serve as a crucial habitat for birds, fish, and other organisms. climate change, ocean acidification and irregular weather events have accelerated human destruction of estuarine environments, threatening countless animals and plants.
the st. lawrence river, the world’s largest estuary, connects the great lakes and the atlantic, but its ecological health is threatened by warming temperatures, lowered oxygen levels and unpredictable weather events.
marine biodiversity losses
more than a third of the ocean’s organisms are threatened by human activity, including anthropogenic climate change, overfishing and pollution. rising water temperatures reduce oxygen availability for organisms and destroy habitats, and this is projected to reduce ocean net primary productivity and biomass production.
coral reefs represent a mere 1% of the ocean, but they provide a habitat for over 25% of all marine organisms, but this biodiversity is threatened by deadly environmental stresses that cause coral to expel their symbiotic zooxanthellae (coral bleaching).
an ocean in crisis 