Ancient Earth was hit by extreme ‘hothouse’ periods of intense dryness, followed by massive rainstorms, a new study reveals. 

Harvard University researchers report that these storms could pour more than a foot rain within hours and were hundreds of kilometres wide.

Earth today is witnessing the devastating effects of even a slight increase in global temperature, such as flooding and droughts. 

But for multiple periods in Earth’s history, our planet experienced hothouse’ periods’ that were around 20°F to 30°F hotter than it is today.  

These periods were likely to have occurred multiple times on Earth in the distant past. They will again occur hundreds of million of years later as the sun continues its brightening, according to their team.

Extreme heat led to episodic deluges on hothouse Earth, report Harvard University scientists (concept image)

Extreme heat led to episodic deluges on hothouse Earth, report Harvard University scientists (concept image)

Jacob Seeley, a Harvard study author, said that if you look at large areas of deep tropics, there’s almost always something raining. 

“But in extreme warm climates, it could be several days without any rain at all over a large part of the sea. 

Then, the rainstorm would suddenly erupt across almost all of the domain and dump a huge amount of water. 

“Then, it would be still for several days before you can repeat the process.”   

Using their model, researchers cranked up Earth’s sea surface temperature to a scalding 130°F, either by adding more carbon dioxide (CO2) – about 64-times the amount currently in the atmosphere – or by increasing the brightness of the sun by about 10 per cent.

According to the team, unexpected things begin happening at these temperatures. 

When the air is extremely hot, such as near the surface, the absorption of sunlight from atmospheric water vapour heats it and creates what’s called an “inhibition layer”.

This barrier prevents convective clouds – which look like stacks of cotton balls – from rising into the upper atmosphere and forming rain clouds. All that evaporated water gets trapped in the atmosphere near the surface.

Convection is the process by which warmer air rises because it’s less dense than surrounding atmosphere. This creates convective clouds.


Convective clouds are like cotton balls stacked up. Convection is the process by which warmer air rises because it’s less dense than surrounding atmosphere. 

Warm air causes strong updrafts due to buoyancy. 

Because condensation emits heat, buoyancy increases even more as the water vapour from the air becomes cloud droplets. 

Source: University of British Columbia 

Clouds can form above the inhibition layer as heat from space is lost. 

All the rain that falls from those high-altitude clouds eventually evaporates, and all of it returns to the atmosphere.

Seeley stated that it’s similar to charging a huge battery. You have both a lot of cooling in the atmosphere, and lots of heating at the surface. This barrier is what separates them. 

“If it can breach that barrier and let the temperature and humidity rise to the cooler upper atmosphere, it is going to bring on a massive rainstorm.”

The barrier is eroded by the heat from the rainstorms in the upper atmosphere over several days. This causes an hour-long deluge as has been seen several times throughout Earth’s past history.

One simulation showed that researchers saw more rain in six hours than what some of the US’s tropical cyclones dropped over several days.

The storm passes and clouds recede. After that, precipitation ceases for several days while the atmosphere recharges.

Seeley stated that “our research shows there are still many surprises in the climate system.” 

‘Although a 30°F 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.’ 

This research sheds light not only on Earth’s past, but also the future. It may help us understand how exoplanets orbit distant stars.

Robin Wordsworth (senior study author) said, “This study has shown rich new physics within a climate which is only a bit different than present-day Earth in a planetary perspective.” 

“It raises huge new questions about Earth’s climate evolution and that of other planets. This is something we will continue to work on for many more years.” 

Nature has published the paper by the team. 


Current research is being done to determine when the different phases of life first appeared on Earth. This date, over 4.5 billion years ago, will be more accurate.

The first human life was thought to have begun in simple cells 3.8 billion year ago

Multicellular life evolved 2.1 billion years ago.

800-600 million years ago, the first mammals appeared. This includes the first arthropods.

It was approximately 475 millions years ago that plants were first introduced to the land.

It was 400 years before insects and seeds were invented.

350 million years ago, amphibians evolved, and reptiles developed 300 million years later. Dinosaurs followed soon after.

200 million years ago, the first mammal appeared.

150 million years ago, birds first developed.

130 million years ago, flowers were born.

Primate species arrived on Earth sixty million years ago.

2.5 million years ago, the genus Homo (including human and pre-human species) was discovered. This led to anatomically modern humans being created 200,000 years later.