Harvard Researchers Find Ancient Earth Faced Severe Rainstorms Amid High Temperatures

Earth was once inundated by episodic cycles of heavy rainstorms followed by severe droughts, according to a study published by Harvard Environmental Science and Engineering researchers in the journal Nature earlier this month.

Robin D. Wordsworth, an Environmental Science and Engineering professor at the School of Engineering and Applied Sciences, and Jacob T. Seeley, a postdoctoral fellow in Environmental Science and Engineering, co-authored the study.

Wordsworth and Seeley created an atmospheric model designed to mimic conditions when Earth was 20 to 30 degrees Fahrenheit hotter. In their simulations, the researchers increased Earth’s sea surface temperature to 130 degrees Fahrenheit, either by adding more carbon dioxide to the atmosphere or by upping the sun’s brightness by roughly 10 percent.

Under those conditions, the sunlight absorbed by atmospheric water vapor forms an “inhibition layer” that traps evaporation in the surface atmosphere. At the same time, clouds form above the inhibition layer, but their rain evaporates into the lower atmosphere before reaching the Earth. After several days, the inhibition layer evaporates, prompting severe rainfall.

After these storms, the Earth would experience several days of dry weather before the cycle repeats, according to the study.

The study has significant implications for understanding the conditions of Earth’s past as well as the conditions on exoplanets, according to Wordsworth. The conditions in the simulations help researchers understand the conditions under which a planet can produce water and sustain life.

“We were looking to go to a world that was up to 310 or 340 Kelvin,” Wordsworth said. “These conditions that are relevant to understanding Earth’s paleo climate — how climate would have behaved in the distant past — but also to exoplanets, or planets around other stars that could have a diverse range of earthlike planets.”

Wordsworth also said these simulations are beneficial towards understanding the impact of climate change in the modern era. He stressed, however, that the severe conditions of the model are far more extreme than current predictions for the impact of climate change in the coming century. Though climate change is a pressing issue, the highest estimates of temperature increases on Earth by 2100 are about 8.6 degrees Fahrenheit.

Nevertheless, Woodsworth said his study can enhance modern conceptions of the impact of climate change.

“This is also a practical motivation of doing a stress test on existing models of climate on Earth — to make our understanding of it more robust,” Woodsworth said.

Woodsworth said he believes the world must take more prompt action to curb harmful emissions and to limit the consequences of climate change.

“The political leadership is not taking the problem seriously enough, so my concern is that we’re going to go slower than we need to be going,” Woodsworth said.