Washington: In its latest research, NASA has revealed that the amount of heat trapped by Earth's land, ocean and atmosphere has doubled over the course of only 14 years raising an alarm over human-caused climate change.
Scientists at NASA and the National Oceanic and Atmospheric Administration (NOAA) in the US found that Earth's energy imbalance approximately doubled during the 14 years from 2005 to 2019.
The scientists concluded after comparing data from two independent measurements -- NASA's Clouds and the Earth's Radiant Energy System (CERES) and data from a global array of ocean floats called Argo that enables an accurate estimate of the rate at which the world's oceans are heating up.
Norman Loeb, lead author and principal investigator for CERES at NASA said that the two very independent ways of looking at changes in Earth's energy imbalance were in good agreement, showing a very large trend, thereby inspiring confidence in the researchers that what they were seeing are a real phenomenon and not just an instrumental artefact.
"The trends we found were quite alarming in a sense," he said in a study published in the journal Geophysical Research Letters.
Increases in emissions of greenhouse gases such as carbon dioxide and methane due to human activity trap heat in the atmosphere, capturing outgoing radiation that would otherwise escape into space.
The warming drives other changes, such as snow and ice melt, and increased water vapour and cloud changes that can further enhance the warming.
The findings showed that the Earth's energy imbalance is the net effect of all these factors.
The study found that the doubling of the imbalance is partially the result of an increase in greenhouse gases due to human activity, also known as anthropogenic forcing, along with increases in water vapour, are trapping more outgoing longwave radiation, further contributing to Earth's energy imbalance.
Additionally, the related decrease in clouds and sea ice leads to more absorption of solar energy.
"It's likely a mix of anthropogenic forcing and internal variability, 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," Loeb warned.
Unless the rate of heat uptake subsides, greater changes in climate that are already occurring should be expected.
"Observing the magnitude and variations of this energy imbalance are vital to understanding Earth's changing climate," said Gregory Johnson, a physical oceanographer at NOAA.