If it’s (still) too good to be on us Terre, it is the result of a subtle balance. enter here Warmth that our planet receives soleil. And the one that emits towards space. To qualify the difference between the two, between the amount ofenergy absorbed in radiationAtmosphere and the amount of radiation on the earth’s surface infrared The thermal emitted towards space, the researchers speak of the radiation balance. and they consider this to be much more important than ordinary surface temperature, intended to judge the extent of Global warming.

Historically, it radiation balance Very little positive. Till now Researchers from NASA and the US Agency for Ocean and Atmospheric Observations (NOAAToday let us tell you that between 2005 and 2019, the imbalance of the Earth’s radiation balance doubled. it remains low – about 0.3% – but “The magnitude of the increase is unprecedented”, emphasizes study lead author Norman Loeb, a NASA Press Release.

To reach these conclusions, the researchers worked on independent datasets. of sensor Ceres program satellites – for clouds and earth radiant power system – which on the one hand measure the energy entering and leaving the Earth system. Argo’s global network of ocean floats that provide accurate Speed by whichthe ocean is warming On the other hand. It absorbs 90% of the excess heat, its temperature really seems to be an indicator of choice. And all this data is consistent.

anthropogenic and natural causes

The main factors causing this imbalance in the Earth’s radiation balance remain to be determined. After investigation, researchers believe this is partly the result of increased concentrations in the atmosphere. green house gas due to human activities. What they call anthropogenic forcing. But this imbalance will also be caused by warming and other effects of natural climate change.

It is now known that greenhouse gases trap heat in the atmosphere. Hence his name, in addition. how? ‘ or ‘ what? By capturing outgoing radiation that would escape into space without them. The resulting warming leads to an increase in water vapor in the atmosphere. However, it also traps part of the outgoing radiation. decline of clouds and sea ice are the cause of more and more absorption solar energy.

The second phenomenon that the researchers point to is the transition of the Pacific Decadal Oscillation (PDO) from a cold phase to a warm phase. Because this natural variability of the Earth system can have a great impact on climate. Between 2014 and 2020, a hot phase of the PDO caused a cloud cover reduction Over the ocean and hence the absorption of solar radiation increased.

While it is difficult to predict what Earth’s radiation balance will look like in the coming decades, the work presented here suggests that changes are to be expected until the rate of heat absorption decreases. more important than the changes already taking place.