Between 2005 and 2019, the Earth’s energy imbalance has roughly doubled, new research has found. Earth’s energy budget can be seen as the amount of solar radiated energy the planet receives from the Sun (absorbed in its atmosphere and surface) versus the amount of thermal infrared energy that Earth re-emits into space. Greenhouse gases have been altering this, trapping more energy and making the average temperature of the planet higher, putting the energy budget at odds.
The energy imbalance is currently at 0.3 percent, which means the Earth is taking on more heat than it is putting back out into space.
NASA and the National Oceanic and Atmospheric Administration (NOAA) measure this budget in different ways. NASA uses its Clouds and the Earth's Radiant Energy System (CERES) suite of satellite sensors, which provides a global picture of the energy budget. NOAA has Argo, a global array of ocean floats that estimate how quickly oceans are warming up. Ninety percent of the excess energy in the energy imbalance is absorbed by the oceans, so this is an important approach.
The new findings, published in Geophysical Research Letters, combines these two approaches, showing that not only do the two agencies' findings agree, but that the increase in carbon dioxide, methane, and other dangerous gas emission is trapping heat in our atmosphere and capturing radiation that would otherwise escape into space.
"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," lead author Norman Loeb, principal investigator for CERES at NASA's Langley Research Center, said in a statement. "The trends we found were quite alarming in a sense."
The effects of human activity on the energy budget is known as anthropogenic forcing and has been shown to be the dominant effect behind the dramatic changes we are witnessing to Earth's climate. But the researchers note that nature has not helped us out during the investigated period, as the Pacific Decadal Oscillation shifted from a cool phase to a warm phase, intensifying the energy imbalance.
"It's likely a mix of anthropogenic forcing and internal variability," said Loeb. "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."
To get your head around the amount of energy the Earth has absorbed in the last 14 years, co-author Gregory Johnson from NOAA’s Pacific Marine Environmental Laboratory told the Washington Post it was the equivalent of all 7.67 billion people on the planet using 20 electric kettles at once or four detonations per second of the atomic bomb dropped on Hiroshima.
There are many factors, both natural and human-made, that contribute to the energy imbalance so predictions for the coming decades remain with significant uncertainties. That said, if the trapping of energy is not reduced, the climate will change even more. "Observing the magnitude and variations of this energy imbalance are vital to understanding Earth’s changing climate," said Johnson.