Scientists have long theorized that Venus formed out of ingredients similar to Earth’s but followed a different evolutionary path. Previously, a computer model of Venus’ ancient climate suggested that Venus may have had a shallow liquid-water ocean. Plus, it had habitable surface temperatures for up to 2 billion years of its early history.
Although massive volcanism that lasted for hundreds to thousands of centuries may have helped transform Venus from a temperate and wet world to the acidic hothouse it is today, suggests a new study by NASA. These “large igneous provinces” in Earth’s past, which led to several major extinctions on our planet millions of years ago, are also discussed in the paper.
Large-scale volcanism that lasted for tens of thousands or possibly hundreds of thousands of years produced large igneous provinces. They can deposit more than 100,000 cubic miles of volcanic rock on the surface. This amount of molten rock could, at its maximum, bury the entire state of Texas a half-mile beneath the surface.
Dr. Michael J. Way of NASA’s Goddard Institute for Space Studies in New York said, “By understanding the record of large igneous provinces on Earth and Venus, we can determine if these events may have caused Venus’ present condition.”
Currently, Venus has an atmosphere with a surface pressure 90 times greater than that of Earth and average surface temperatures of roughly 864 F. The study suggests that these extreme volcanic eruptions may have caused these conditions at some point in Venus’ distant past. In particular, multiple such eruptions within a short geologic time (within a million years) may have caused a runaway greenhouse effect that sparked the planet’s change from a temperate and wet climate to a scorching and dry one.
Way said, “Large fields of solidified volcanic rock cover 80% of Venus’ surface. While we’re not yet sure how often the events which created these fields occurred, we should be able to narrow it down by studying Earth’s history.”
Since the beginning of multicellular life approximately 540 million years ago, at least five significant mass extinction events have each wiped out more than 50% of the animal life on Earth. The majority of these extinction events, according to this study and those that came before it, were brought on by or made worse by the kinds of eruptions that result in massive igneous provinces. For reasons that Way and other scientists are currently investigating, the temperature changes brought on by these events did not have the same impact on Earth’s climate as they did on Venus.