An artist’s impression of the surface of Venus. Image via Shutterstock / The Conversation.
By Richard Ernst, Carleton University
We can learn a lot about climate change from Venus, our sister planet. Venus currently has a surface temperature of 840 degrees F (450 degrees C) – the temperature of an oven self-cleaning cycle – and an atmosphere containing carbon dioxide (96%) with a density 90 times the temperature of the Earth.
Venus is a very strange place, completely uninhabited, but perhaps in the clouds about 40 miles (60 km) up where a recent discovery of phosphine may reveal the life of floating microbes. But the surface is completely unstable.
However, Venus seemed to have a Earth-like climate. According to recent climate modeling, for much of Venus the surface temperature of Venus was similar to that of Earth today. There also seems to have been oceans, water, perhaps snow, perhaps continents and tectonic plates, and even more speculative, perhaps even surface life.
Less than a billion years ago, the weather changed dramatically as a result of the runaway greenhouse effect. It can be argued that an intense period of volcanism sent enough carbon dioxide into the atmosphere to cause this climate change event that eroded the oceans and caused the end of the water cycle.
Evidence of change
This idea was inspired by climate moderators Sara Khawja, a master’s student in my group (co-led by geologist Claire Samson), to find evidence in Venusian rocks for this past climate change event. recommend.
Since the early 1990s, my research team at Carleton University – and most recently my Siberian team at Tomsk State University – have been mapping and explaining the geological and tectonic history of Earth’s amazing planet sister.
The Soviet missions of Venera and Vega in the 1970s and 1980s landed on Venus and took photographs and assessed the composition of the rocks, before the rulers failed due to the high temperature and pressure. However, our most complete view of the Venus surface was provided by NASA ‘s Magellan spacecraft in the early 1990s, which used radar to see through the dense cloud stage and to take detailed images of more than 98% of the surface. Venus.
A photograph of the surface of Venus produced by radar aboard the Magellan spacecraft.
Old rocks
As a result of our research for geological evidence of the major climate change event, we focused on the oldest type of rock on Venus, called tesserae, which has a complex appearance resembling a long, complex geological history. . We believed that these older rocks had the best chance of evidencing water erosion, a process that is as important on Earth as it should have been on Venus before the major climate change event.
Because there were high resolution data, we used an indirect method to try to identify old river valleys. We showed younger lava flowing from the volcanic fields around filled valleys on the edges of tesserae.
To our surprise these tesserae valley patterns are very similar to river flow patterns on Earth, leading to our suggestion that these tesserae valleys were formed by river erosion at a time with an Earth-like climate. My Venus research groups at Carleton and Tomsk State universities are studying post-tesserae lava flows for any geological evidence of the transition to extreme hot conditions.
The first feature on Venus identified from Earth-based radar was a compilation of Alpha Regio, a topographic plateau on the surface of Venus. Image via NASA-JPL.
Ground analyzes
To understand how volcanism on Venus could bring about such a change, we can look at the history of the Earth for analogs. We can find analogies in large explosions such as the last Yellowstone eruption 630,000 years ago.
But such volcanism is small compared to large igneous areas (LIPs) that occur about every 20-30 million years. These explosive events can release enough carbon dioxide to cause climate change on Earth, including major depletion. To give you a sense of scale, imagine that the smallest LIPs produce enough magma to cover the whole of Canada to a depth of about 30 feet (10 meters). The best-known LIP produced enough magma that would have covered an area the size of Canada to a depth of nearly 5 miles (8 km).
The LIP analogues on Venus include individual volcanoes that are up to 300 miles (500 km) across, wide lava channels that reach up to 4,300 miles (7,000 km) in length, and co-propulsion systems. also associated with them – where the bark separates – up to 6,000 miles (10,000 km) long.
If LIP-style volcanism was to blame for the major climate change event on Venus, then could climate change occur on Earth? We can imagine the situation of millions of years in the future when several LIPs could occur randomly at the same time causing such climate change on Earth leading to situations like Venus the today.
Richard Ernst, Scientist in Residence, Earth Sciences, Carleton University (also a professor at Tomsk State University, Russia), Carleton University
This article is republished from The Conversation licensed under Creative Commons. Read the original article.
Baseline: Venus has a surface temperature of 840 degrees F (450 degrees C) and an atmosphere containing carbon dioxide, with a density 90 times higher than Earth. However, for much of history, Venus seems to have had an Earth – like climate, with oceans, water, perhaps snow, perhaps continents and tectonic plates, and even more speculative, perhaps even life. cream. Then, less than a billion years ago, Venus ’climate changed dramatically as a result of the runaway greenhouse effect.
