Venus is sometimes called Earth’s sister planet. It sounds strange since the two seem nothing alike. One is a lifeless rock, while the other is teeming with organisms who are sustained by enormous quantities of water. 

However, recent scientific modelling suggests that at one point in history, Earth was the lifeless planet of the two, while Venus had surface temperatures similar to present-day Earth.

As climate change becomes an increasingly common concern in the global subconscious, researchers at Carleton University have published an article with new evidence to support the theory that Venus was once an Earth-like planet, until climate change turned it into the desolate planet it is today. 

Carleton earth sciences professor Richard Ernst along with graduate student and lead author Sara Khawja published the theory in Nature Communications about how the surface of Venus may have been shaped by water—something that disappeared as the planet’s CO2 levels drastically increased.

https://twitter.com/NASA_Marshall/status/1364984505577201665

How Venus’s climate changed 

Ernst and Khawja’s research built on recent evidence that shows Venus may have had an Earth-like temperature and surface conditions. According to Ernst, this means the planet likely had water and rain, as well as possible continents with shifting plates beneath the surface. 

There’s even a chance it might have once held life. 

“At one point, if Venus had Earth-like conditions, that means something catastrophic happened to cause the temperatures to skyrocket, and it went from a habitable planet to… well, it’s 450 degrees on the surface of Venus. There’s no way for something to live on that,” Khawja said. 

There are several theories about why Venus’s temperature might have skyrocketed. Ernst, who researches extreme volcanism, said he favours the theory that volcanic eruptions on the planet’s surface spewed CO2 into the atmosphere. The high CO2 content would have trapped all the heat released from the planet’s core or its surface, causing the temperature to drastically increase. 

Scientists are certain CO2 is at fault. Mercury is closer to the sun than Venus, but the surface of Venus is hotter than Mercury because its CO2 rich atmosphere—which Mercury does not have—traps heat on the planet. 

Ernst and Khawja’s research supports the theory of climate change on Venus by examining tesserae—the oldest type of rock visible on Venus—and finding evidence that they could have been eroded by water. The tesserae are so old that they would have existed during the time Venus had Earth-like conditions. 

[Graphic by Sara Mizannojehdehi]

A window into the research process

The published research paper went through several rounds of revisions before it was accepted by Nature, and both scientists expressed exhaustion about the process of rewriting, adding and revising their work, but felt it was ultimately for the best. 

“One of the most interesting things about this paper is that it challenges the science we already assume about Venus, which I think is its greatest accomplishment so far,” Khawja said.

Theories which challenge things that scientists think they already understand can be hard to get off the ground, Khawja explained, so she and Ernst were determined to have their paper accepted. 

“As a young scientist, it’s very important to me that we don’t stick to one way of thinking,” she said.

To understand the theory more clearly and gather evidence which further supports their hypothesis, Khawja and Ernst need better technology to go to Venus and gather data. 

Ernst is involved with a Russian mission named Venera-D aiming to do just that, reaching Venus with a lander and potentially even drilling into the planet. If there was once life on Venus’s surface, there is even more reason to believe that life might still exist in its atmosphere. Venera-D aims to find it. 

Ernst said multiple organizations are interested in investigating that possibility, but Venera-D is the only confirmed mission. 

“Potential life in the Venusian clouds is really exciting,” he said, “and it’s relevant to what we’re doing, because we’re trying to understand the conditions on Venus when it was Earth-like, what the transition looked like, and whether life could have migrated—as the climate changed—from the surface up into the clouds.”

Researching for a better future

Khawja, whose interest is primarily in climate change research, said she came away from the research project with a sense of urgency.

“One thing that people don’t understand is that if we don’t understand what happened to Venus, it might happen to Earth—or something similar,” she said.

Brian Cousens, the earth sciences department head at Carleton, said geological and human influences are the two forces now pushing climate change. 

“In Earth’s history, we’ve had rapid CO2 changes in the atmosphere when there were no people around at the time,” Cousens said. “Now we have that second force: what we are doing. There’s no doubt that people are pushing and adding to those geological processes that control climate change.” 

Ernst cited research by David Kidder and Thomas Worsley at Ohio University, who investigated how long humanity could keep pushing our current levels of CO2 into the atmosphere until there was a mass extinction event. The findings showed that it was only a matter of a few hundred years before CO2 would get to the level of wiping humanity off the map.

Cousens said we know humans are having an impact on atmospheric CO2 levels, but the remaining question is how much of the current CO2 input is caused by geological versus human factors.

“I think we’ve reached the point that it doesn’t matter anymore,” he said. “This is just a personal opinion, but I think we need to move forward on any process that lowers our CO2 production or helps to extract CO2 out of the atmosphere.”

Climate change denial 

Khawja said despite scientific evidence, there are many people who don’t believe human behaviour is affecting climate change. 

Some say climate change deniers are a result of misinformation. According to global survey results reported by Reuters, 57 per cent of those surveyed believe government leaders, business chiefs and journalists are spreading falsehoods or exaggerations to citizens. 

Khawja said this public distrust of institutions can be frustrating for scientists. 

“If you categorize everything you read as ‘fake news,’ then it’s difficult to recognize scientists who have the world’s best interests at heart,” she said. “I love science, and all I really want to do is educate the people around me in the best possible way.”

Ultimately, Khawja said she thinks the people pioneering modern climate change research are pressing on for the betterment of science, without taking too much stock of deniers’ claims.

In her own research, she said she is sure understanding what happened to Venus is crucial to understanding what might happen to Earth.

The Carleton University earth sciences department is located in Herzberg Laboratories.

From one grad student to another

Though every graduate student in the earth sciences department must complete a thesis project to earn their degree, not all of them have been published in Nature.

“I know that Nature is kind of like winning the Oscars for scientists. It is a very reputable journal and it’s highly recognized,” Khawja said. “I know a lot of people whose goal is, in 15 years … to be able to publish in Nature. The fact that I’ve accomplished this at such an early stage in my career is crazy to me.”

Khawja said for many graduate students in her field, coming up with ideas is the easy part, and writing them down is another story entirely. 

“If you get really stressed or if you are demotivated, turn off for a few seconds the logistics of your paper, turn off the anxiety that comes with writing, and focus on what you love—the science behind your work,” she said. 

Khawja said focusing on science will reinvigorate students’ passion.

“When things take time, you get really demotivated. Giving up seems like the easier option. Moving on to something else always sounds way better than continuing to push a topic that keeps being shut down,” she said. 

“But at the end of the day, if you truly believe in what you’re doing and the science behind it, then just keep trying.”

Featured graphic by Jillian Piper.

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