The amount of heat trapped by Earth’s land, ocean, and atmosphere doubled over the course of just 14 years, a new study shows.

To figure out how much heat the earth was trapping, researchers looked at NASA satellite measurements that tracked how much of the Sun’s energy was entering Earth’s atmosphere and how much was being bounced back into space. They compared this with data from NOAA buoys that tracked ocean temperatures — which gives them an idea of how much heat is getting absorbed into the ocean.

The difference between the amount of heat absorbed by Earth, and the amount reflected back into space is called an energy imbalance. In this case, they found that from 2005 to 2019, the amount of heat absorbed by Earth was going up. Their results were published in Geophysical Research Letters this week.

“The two very independent ways of looking at changes in Earth’s energy imbalance are in really, really good agreement, and they’re both showing this very large trend, which gives us a lot of confidence that what we’re seeing is a real phenomenon and not just an instrumental artifact,” said Norman Loeb, a NASA researcher and the lead author for the study in a press release. “The trends we found were quite alarming in a sense.”

NASA/Tim Marvel

The researchers think that the reason the Earth is holding on to more heat comes down to a few different factors. One is human-caused climate change. Among other problems, the more greenhouse gases we emit, the more heat they trap. It gets worse when you take into account that increasing heat also melts ice and snow. Ice and snow can help the planet reflect heat back into space — as they disappear, more heat can be absorbed by the land and oceans underneath.

There’s another factor at play too — natural changes to a climate pattern called the Pacific Decadal Oscillation. Between 2014 and 2019, the pattern was in a ‘warm phase’ which caused fewer clouds to form. That also meant more heat could be absorbed by the oceans.

More than likely, it’s the combination of climate change with those natural shifts that made such a big difference to Earth’s energy balance, Loeb says. “And over this period they’re both causing warming, which leads to a fairly large change in Earth’s energy imbalance. The magnitude of the increase is unprecedented.”

Fourteen years isn’t a long time compared to Earth’s long climate history — researchers will have to keep gathering data to get more information about how this fits into the complete picture of the planet’s energy imbalance.

“My hope is the rate that we’re seeing this energy imbalance subsides in the coming decades,” Loeb told CNN. “Otherwise, we’re going to see more alarming climate changes.”