The massive amounts of carbon dioxide and other greenhouse gases that have entered our atmosphere since the Industrial Era began in the 18th century have had significant effects on the world’s oceans.
Solar energy striking Earth is either reflected back into space or absorbed and then radiated back as heat. Greenhouse gases trap some of that heat. Because they are accumulating in the atmosphere, excess heat is accumulating too, and the Earth is warming.
“Greenhouse gases like carbon amplify the amount of excess heat left over because they prevent heat energy from releasing from Earth’s system,” says oceanographer Tim Boyer of the National Oceanographic and Atmospheric Administration.
Excess heat trapped in the atmosphere by our greenhouse gases spreads into the oceans. They've absorbed about 90 percent of that heat. As a result, they've been warming steadily for a long time.
Sea surface temperatures over the last several decades reflect such warming, but are also sensitive to weather events like hurricanes and El Nino. That explains why temperatures fluctuated from one year to the next as far back as the mid-1800s....