Often, when we think of climate change, we don’t get past the changes in global temperatures. Those effects certainly contain enough potential for disaster. But there are chemical changes taking place beyond just adding 40 billion tons of carbon to the atmosphere each year. Those high levels of CO2 in the air are leading to increased uptake of CO2 in water, which in turn forms carbonic acid, causing ocean acidification. That acidification contributes to coral bleaching, to changes in ecosystems, and to reducing the ocean’s role as a buffer for the atmosphere.
And there’s still another effect. Hot water simply can’t contain as much dissolved oxygen as cooler water. So as the ocean levels warm, oxygen levels decline.
A drop in the amount of oxygen dissolved in the oceans due to climate change is already discernible in some parts of the world and should be evident across large parts of the ocean between 2030 and 2040, according to a new study.
Scientists know that a warming climate can be expected to gradually sap oceans of oxygen, leaving fish, crabs, squid, sea stars, and other marine life struggling to breathe.
About 251 million years ago, the world got warm. An increase in CO2 from volcanoes led to rising temperatures, an acidified ocean, and a crash in oxygen levels both in the sea and in the atmosphere. As a result, 96 percent of all marine species disappeared. The oceans became a sour, empty place. It took 10 million years for the planet to recover.
Things don’t have to get that bad to be bad.
...unusually hot weather could lead to natural “dead zones” in the ocean, where fish and other marine life cannot survive.