Early Earth was battered by ‘tremendous’ rainstorms — and scientists warn it may happen again

CAMBRIDGE, Mass. — In its infancy, Earth did not have rain showers like today, but instead endured massive storms capable of dumping more than a foot of water in just a few hours, according to new research.

The massive deluges occurred because the planet was around 20 degrees Fahrenheit (11 Celsius) hotter than today. Researchers believe the planet will experience the same kind of climate in the future as the sun continues to brighten.

“This study has revealed rich new physics in a climate that is only a little bit different from present-day Earth from a planetary perspective,” says study senior author Robin Wordsworth, a professor of environmental science and engineering at Harvard University, in a statement. “It raises big new questions about the climate evolution of Earth and other planets that we’re going to be working through for many years to come.”

Wordsworth and co-author Jacob Seeley created models that studied how Earth reacted to the extremely hostile atmosphere. The sea-surface temperature was increased to a scalding 130 degrees Fahrenheit (54 Celsius) either by adding more carbon dioxide – about 64 times the amount currently in the atmosphere – or by increasing the brightness of the sun by 10 percent.

At these temperatures, the air near the surface becomes extremely warm, absorption of sunlight by atmospheric water vapor heats the air above the surface and forms what’s known as an “inhibition layer.” This is a barrier that prevents convective clouds from rising into the upper atmosphere and forming rain clouds.

Instead, all that evaporation gets stuck in the near-surface atmosphere.

At the same time, clouds form in the upper atmosphere, above the inhibition layer, as heat is lost to space. The rain produced in those upper-level clouds evaporates before reaching the surface, returning all that water to the system.

Researchers compare it to a “massive battery.” If something can break through that barrier and allow the surface heat and humidity to break into the cool upper atmosphere, an enormous rainstorm will happen.

“If you were to look at a large patch of the deep tropics today, it’s always raining somewhere,” says Seeley. “But we found that in extremely warm climates, there could be multiple days with no rain anywhere over a huge part of the ocean. Then, suddenly, a massive rainstorm would erupt over almost the entire domain, dumping a tremendous amount of rain. Then it would be quiet for a couple of days and repeat. Our research goes to show that there are still a lot of surprises in the climate system.”

He adds: “Although a 30-degree increase in sea surface temperatures is way more than is being predicted for human-caused climate change, pushing atmospheric models into unfamiliar territory can reveal glimpses of what the Earth is capable of.”

The findings are published in the journal Nature.

South West News Service Joe Morgan contributed to this report.

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