The Most Powerful Evidence Climate Scientists Have of Global Warming
The oceans hold the story of a planet warming as fossil fuels are burned. Here is what scientists have discovered
Insideclimatenews.com, Oct. 3, 2017
Earth's temperature is rising, and it isn't just in the air around us. More than 90 percent of the excess heat trapped by greenhouse gas emissions has been absorbed into the oceans that cover two-thirds of the planet's surface. Their temperature is rising, too, and it tells a story of how humans are changing the planet.
This accrued heat is "really the memory of past climate change," said Kevin Trenberth, the head of climate analysis at the National Center for Atmospheric Research and co-author of a new paper on ocean warming.
It's not just the amount of warming that is significant—it's also the pace.
The rate at which the oceans are heating up has nearly doubled since 1992, and that heat is reaching ever deeper waters, according to a recent study. At the same time, concentrations of carbon dioxide in the atmosphere have been rising.
Scientists say the accumulation of heat in the oceans is the strongest evidence of how fast Earth is warming due to heat-trapping gases released by the burning of fossil fuels.
Oceans have enormous capacity to hold heat. So ocean temperatures, unlike temperatures on land, are slow to fluctuate from natural forces, such as El Niño/La Niña patterns or volcanic eruptions. Think night and day, said Trenberth. As night falls on land, so do air temperatures. But in the oceans, temperatures vary little.
This makes it easier to tease out the influence of human-caused climate change from other possible causes of surging ocean heat.