Extreme Heat Followed by Downpours Once Characterized ‘Hothouse Earth’

New research has found that the so-called hothouse Earth periods in our planet’s remote past were actually periods of extreme hot dry temperatures, hotter than today by 20-30 degrees Fahrenheit (17 degrees Celsius), followed by rain deluges hundreds of miles wide that could offload as much as a foot (30 centimeters) of rain in just a few hours. In hothouse Earth periods burning heat would have been cyclically followed by massive precipitation, a new study published by Harvard University suggests.

Undertaken by scientists from Harvard , the study has been published in the journal Nature. The scientists have modeled epochs of extreme heat on our planet using computer simulations and think their findings may not only help understand the Earth’s remote past but also its hundreds of millions of years distant future as the Sun continues to brighten. Furthermore, the study’s findings may also help us to understand the climates of exo-planets outside of our solar system.

Mail Online quotes Jacob Seeley, the lead author of the study as saying:

"If you were to look at a large patch of the deep tropics today, it's always raining somewhere. 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."

If this landscape is in a hothouse Earth period then the massive rainfall and storms are a “natural” consequence of extreme heat, says the latest study from Harvard University. (John / Adobe Stock)

Hothouse Earth Cycles: An “Unexpected Atmospheric State”

This cycle is a "new and completely unexpected atmospheric state" said the study’s co-author Robin Wordsworth according to a Harvard John A Paulson School of Engineering and Applied Sciences release. The researchers produced a series of simulations, in some cases increasing the surface temperatures by a whopping 130 degrees Fahrenheit (54 degrees Celsius), either by adding more carbon dioxide, about 64 times the current levels, or by increasing the sun’s brightness by about 10 per cent.

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These temperature jumps produced unexpected results. When the air near the surface becomes extremely warm, absorption of sunlight by atmospheric water vapor heats the air above the surface and forms an “inhibition layer” that prevents convective clouds from rising into the upper atmosphere and forming rain clouds. Instead, all that water vapor 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. According to Science Alert, Seeley explained, "It's like charging a massive battery. You have a ton of cooling high in the atmosphere and a ton of evaporation and heating near the surface, separated by this barrier. If something can break through that barrier and allow the surface heat and humidity to break into the cool upper atmosphere, it's going to cause an enormous rainstorm."

And this is just what happens with several days of evaporative cooling from the upper atmosphere’s rainstorms eroding the barrier and triggering a gigantic rainstorm. And hothouse Earth experienced these savage storms regularly, or rather cyclically after days of scorching dry heat. In one simulation, the rain clouds released more rainfall in six hours than tropical cyclones cause in the US across several days. Once all that water has been released, the rain stops for several days while the atmospheric battery recharges and the cycle repeats.

Clearly hothouse Earth cycles have implications for life on our planet in the coming decades or centuries because too hot somewhere means too wet somewhere else. (piyaset / Adobe Stock)

What Can We Learn From The Harvard Study For The Future?

Current predictions of global warming don’t expect the earth to achieve the study temperatures anywhere in the near future, in fact not for hundreds of millions of years. However, says Seeley, "Our research goes to show that there are still a lot of surprises in the climate system. 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."

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It’s certainly something climate scientists need to take note of and, as Wordsworth puts it, "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."

Top image: Hothouse Earth cycles, as proven by Harvard University's latest study, are extreme in heat and in rain with one following the other. Our near future will not be so extreme, but similarities are already apparent in droughts and deluges in many regions of planet Earth. Source: Günter Albers / Adobe Stock

By Sahir Pandey