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The amount of energy stored in the earth has almost doubled in just 14 years, report experts from the American space and ocean agencies Nasa and NOAA in a study in the specialist journal »Geophysical Research Letters«.
That amplifies the global temperature increase.
The cause is likely a mixture of man-made factors and natural variability, said Nasa researcher Norman Loeb, who led the study.
Both factors would have favored warming and thus contributed to the imbalance in the energy balance.
The extent of the increase is "unprecedented".
Most of the heat is stored in the oceans
The climate on earth depends, among other things, on how much heat radiation from the sun is absorbed by the atmosphere, soils and oceans and how much is emitted back into space as thermal infrared radiation.
"A positive energy imbalance means that the earth system is absorbing energy, which causes the planet to heat up," writes NASA.
For the study, the experts evaluated satellite data on the earth's thermal radiation and information from the Argo program from 2005 to 2019.
As part of Argo, a fleet of robots has been used to record temperature, salinity and currents in the world's oceans since 2000.
Since the oceans absorb almost the entire amount of energy from the imbalance on earth, the amounts of heat captured by the satellites are reflected in temperature changes in the oceans.
"The two independent perspectives agree very well," says Loeb.
This makes it clear that this is a real phenomenon.
Snapshot of long-term climate change
Higher amounts of greenhouse gases in the atmosphere increasingly reduce the thermal radiation that the earth can give back into space.
The resulting warming of the earth in turn favors the melting of the ice and influences the formation of clouds, which also has an impact on the climate.
Since 2005, the amount of greenhouse gases such as carbon dioxide (CO₂) and methane in the atmosphere has increased further.
At the same time, a natural weather phenomenon in the Pacific, the so-called Pacific Decade Oscillation (PDO), has shifted from a cooler phase to a warmer one and the energy imbalance has continued to develop in the direction of an excess, the researchers report.
Since around 2014, the PDO has led to a reduction in cloud cover over the ocean, so that it absorbs more solar radiation.
In this respect, the work is a snapshot, explained Loeb.
It is not possible to predict with certainty how the earth's energy balance will develop in the coming decades.
If the amount of energy absorbed by the earth does not decrease, however, much greater climate changes are to be expected than have already occurred.