published on 24 June 2021 in air
A new study explains how the Earth’s energy balance is changing
The Earth’s climate is based on a delicate balance between the incoming energy, arriving from the Sun mainly in the form of light, and the outgoing energy, radiated from the Earth into space in the form of heat (infra-red thermal radiation). Their sum determines whether the Earth becomes warmer or cooler. Since human emissions of greenhouse gases trap more heat within the Earth’s atmosphere, this balance is changing. According to a study carried out by NASA and the U.S. Agency for Oceanic and Atmospheric Observation (NOAA), the amount of heat that arrives from the Sun and that is absorbed by the Earth has doubled in the last fifteen years. The analysis, published in the scientific journal, Geophysical Research Letters stresses that the difference between the energy coming from the Sun and re-emitted from our Planet, compared to that absorbed, has never been higher.
Most of this excess energy (about 90%) warms the oceans, while the rest warms the earth, melting snow and ice and heating the atmosphere. The study compares satellite observations of Earth’s net absorbed radiant energy with a global set of measurements used to determine warming within the oceans, land, and atmosphere and the melting of snow and ice. The researchers showed that these two independent approaches have produced an increase in the rate at which Earth absorbs energy from mid-2005 to mid-2019, which is attributed to a decrease in the reflection of energy back into space by clouds and sea ice (albedo) and an increase in greenhouse gases and water vapour. All this, according to the study, is also thought to be compounded by the transition of the Pacific Ocean from a “cold phase” to a “warm phase”, a natural phenomenon known as the Pacific Decadal Oscillation.
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