More rapid heating of Earth caused by changes in cloud over the ocean

What is it about?

The amount of sunlight absorbed by Earth is more than the energy emitted back to space which means more energy is arriving than leaving, and this is making our planet heat up. This heating is also becoming stronger, meaning that climate change is accelerating. We show the growth in Earth's rate of heating is linked to greater amounts of sunlight absorbed and this is strongest over the cloudy parts of the oceans. An additional finding was that western China is reflecting less sunlight than expected, probably due to measures to reduce air pollution. The rise in global temperatures is consistent with the extra energy that is being absorbed by the uppermost layers of the ocean. However, the rapid warming from 2022 to 2023 can only be explained if this heating is being focused on a shallower layer of ocean water or that there is extra heating coming from deeper layers of the sea. More heating from below the sea surface is consistent with a known natural ocean fluctuation called El Niño that developed in 2023. There still needs to be more research to find out why the planet is reflecting less sunlight back to space, like a dirty mirror. Possible reasons are that clouds are becoming fewer and less bright as the planet warms but it also may be explained by cleaner air that can cause more sunlight to reach the ground.

Featured Image

Photo by Joseph Barrientos on Unsplash

Photo by Joseph Barrientos on Unsplash

Why is it important?

Incomplete understanding of increases in Earth's energy imbalance and ocean warming reduces the capability to accurately prepare for near term climate change and associated impacts. We found in observatios that cloudy ocean regions are reflecting less sunlight back to space and this was the main cause of the ever growing rates at which the Earth is heating up and warming. Another puzzle was the jump in warming in 2023. We found that the rapid ocean warming in 2023 can only be explained if heating from rising greenhouse gases and cleaner air is focused on a narrower layer of the ocean or if it is added to heat returning from the ocean depths. This new interpretation of the drivers of Earth's energy budget changes and their links to ocean warming can improve confidence in near term warming and climate projections.

Perspectives

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This was work done over the summer of 2024 after finding some interesting results from satellite observations of energy arriving and leaving at the top of Earth's atmosphere. Following some coffee room discussions with a colleague we wrote two papers, one on the acceleration of ocean warming and this one trying to understand what regions were copntributing most to the increase in sunlight absorbed by the planet.

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