Direct observations now also show that we are shaking our earth’s energy budget.

We really can no longer ignore it.

The earth has a delicate balance. Our planet is constantly trying to balance the flow of energy in and out of the earth system. Unfortunately, human activities are turning this balance upside down, warming our planet. This phenomenon has already been discussed several times using climate models. But now, for the first time, researchers have confirmed this using direct observations.

Energy budget
The fragile energy balance of the earth is also called the energy balance. How does it work exactly? The exchange of energy between Earth and space takes place exclusively by radiation. Radiant energy enters the Earth system through the sunlight that shines on our planet. Some of this energy bounces off the surface of the Earth or the atmosphere in space. The rest is absorbed, heats the planet, and then is radiated as radiant thermal energy. It can be compared to how black asphalt heats up and radiates heat on a sunny day. Ultimately, thermal radiant energy also goes into space, although some of it is absorbed by clouds and greenhouse gases in the atmosphere. The absorbed energy can also be sent back to Earth, further warming the surface.

Animation of the energy balance of the Earth. Normally, the energy balance is in equilibrium between incoming (yellow) and outgoing (red) radiation. However, on Earth, natural and man-made processes affect the amount of energy received and the amount of energy returned to space, creating an imbalance. Image: Conceptual Imagery Lab at NASA’s Goddard Space Flight Center

Out of balance
Unfortunately, we know that the Earth’s energy budget is out of balance. We also know why. Adding more radiation-absorbing components – think greenhouse gases – or when radiation-absorbing components are removed – like aerosols – it upsets the Earth’s energy balance. In this case, more energy is absorbed by the earth than escapes into space. Also called radiative forcing, it is the primary way in which human activities affect the climate.

Direct observations
Climate models had previously predicted that greenhouse gases and aerosols emitted by humans will affect the Earth’s energy budget. But now, for the first time, researchers have confirmed these predictions with direct observations. This means that there is now evidence that radiative forcing resulting from human actions is increasing, which in turn affects the planet’s energy balance and ultimately causes climate change. “This is the first calculation of Earth’s total radiative forcing using global observations, taking into account the effects of aerosols and greenhouse gases,” said researcher Ryan Kramer. “This is direct evidence that human activities are causing changes in the Earth’s energy budget.”

technical
How do researchers come to this conclusion? Scientists have been monitoring the flow of radiation at the top of Earth’s atmosphere using satellites for some time. This gives us a good understanding of the amount of energy flowing in and out of the earth system. These data, combined with other data – such as ocean heat measurements – show an imbalance in Earth’s energy balance. “However, that doesn’t tell us what factors are causing the observed changes in energy balance,” Kramer says. To find out how much influence humans have on the energy budget, the researchers first calculated how much of the observed imbalance was caused by natural fluctuations, such as water vapor, clouds, temperature, and albedo (the power reflection). Then they subtracted these values ​​from the total. The part that remains is the radiative forcing.

Radiation forcing
The team found that human activities resulted in an increase in Earth’s radiative forcing of about 0.5 watts per square meter between 2003 and 2018. This increase is mainly due to greenhouse gas emissions from, for example example, energy production, transport and industrial production. The reduction in reflective aerosols also contributes to the imbalance.

The new technique applied is a promising method for closely monitoring radiative forcing. Because the technique is faster than previous model-based methods, researchers are able to measure radiative forcing in nearly real time to follow. The technique could therefore be used to track how human emissions affect the climate and to monitor the effectiveness of different mitigation strategies. “This allows us to make better predictions of how the climate will change in the future,” concludes researcher Gavin Schmidt.

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