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Thursday
Apr062017

Venus: How Not To  Earth

As Carbon Dioxide levels increase in our own atmosphere, climate scientists have been looking outward to study the Greenhouse Effect on one of our closest neighbours and how it can provide valuable insight into what lies ahead of us.

Safe to say we’re all familiar with the Greenhouse Effect; the warming of the atmosphere via gases that absorb heat. In moderate abundance “greenhouse gases” such as water vapour, methane, ozone, carbon dioxide and nitrous oxide, pose no threat and are essential for life, but like anything too much of a good thing can be harmful. This is what makes Venus such a bad omen.   

Venusian history

Scientists believe that Venus was once like Earth, with an atmospheric temperature cool enough to harbour liquid water on its surface. Venus even has the same geological composition and internal activity, but its proximity to the sun caused it to begin heating up.

By NASA [Public domain], via Wikimedia CommonsVenus’s atmosphere consists of Carbon Dioxide and water vapour, two of the most effective greenhouse gases. The heat trapped over time by these reached temperatures capable of vaporising carbonates out of the rocky surface into CO2. This Greenhouse Effect exponentially facilitated the release of more Carbon Dioxide, exacerbating the Greenhouse Effect further, releasing even more CO2 from the rocks, and so on…

This heat also meant that liquid water that was once on the surface of Venus would have been vaporised; perhaps entire oceans boiling off into water vapour, which not only added to the greenhouse warming, but also synthesised with sulphites into sulphuric acid. The sulphuric acid was raised into the atmosphere, resulting in thick clouds that trapped the heat between themselves and the surface.

This is what’s known as the Runaway Greenhouse Effect, and has made Venus into the hottest planet in the Solar System with an average temperature of 462°C. Despite being the second closest to the sun Venus exceeds the temperatures of Mercury, perfectly demonstrating the dangers of CO2.

What can we do?

As we all know CO2 is a problem here on Earth and if we don’t limit our emissions soon enough to stay below an atmospheric warming of 2°C, we could be headed down the same path as our neighbour. It may not sound like much, but a one or two degree global temperature difference is all it takes to catalyse the preliminary stages of Runaway Greenhouse Effect.

One thing that could alleviate this process for us is the albedo effect; the percentage of solar heat bounced back into space by reflective surfaces. However, the surface with the highest reflectivity on Earth is snow on ice, an asset we are quickly losing to climate change.

By NASA/Goddard Space Flight Center Scientific Visualization Studio The Blue Marble data is courtesy of Reto Stockli (NASA/GSFC) MerveillePédia [Public domain], via Wikimedia CommonsAs Runaway Greenhouse Effect is a net-positive feedback loop, so too is the climate action we need to take. To lower CO2 and other greenhouse gas emissions is to safeguard glaciers and ice caps necessary for deflecting heat. More snow and ice equals more heat reflected into space, leaving less heat available for absorption by greenhouse gases and the Earth’s surface, allowing the growth of more ice and snow and so on...

Ironically Venus’s dense sulphuric clouds have made it the second most reflective body in our solar system with an albedo of 65%, but the very thing that could have saved it is a direct product of its Runaway Greenhouse Effect. Luckily however, we’re here. We have the power to destroy, as seen through our current driving of climate change, but we also have the power to observe and undo the damage we’ve done.

"...Venus is an ominous reminder that in a world rather like the earth, things can go wrong. There is no guarantee that our planet will always be so hospitable.  To maintain this clement world, we must understand it and appreciate it. The runaway greenhouse effect on Venus is a valuable reminder that we should take the increasing greenhouse effect on earth seriously.” – Carl Sagan

By looking at Venus we know what could potentially happen if we do nothing. And know that if we do not protect our own albedo assets and limit our CO2 emissions through adequate climate action it could be too little too late for us as well.

By Thomas Phillips - Online Journalism Intern

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