Venus may be our planet’s closest neighbor in the solar system, but its atmosphere seems world away from Earth’s oceans, ice caps and greenery. Where our world hosts an ecosystem that supports all kinds of life, Venus is a gaseous wasteland, its oceans long gone and its surface hotter than an open fire.
However, as this week’s COSMOS: A Spacetime Odyssey explores, Earth and Venus may not be as different as they seem. CO2, or carbon dioxide gas, smothers Venus in heat, creating a dense atmosphere that blocks the small amount of sunlight that reaches the planet’s surface from getting back out. The CO2 creates an inferno, a dramatic greenhouse effect that makes life on the planet impossible.
Luckily for us, Earth’s chances of survival are worlds apart from Venus. The runaway greenhouse effect that rendered Venus uninhabitable is more extreme than anything Earth can ever encounter – our planet’s makeup of oceans prevents that fate. However, when looking at the measured increase in CO2 in our atmosphere, it’s hard not to associate the greenhouse gases that consumed Venus with those that are warming our planet today. After all, Venus and Earth started out with about the same amount of carbon.
As COSMOS explains, climate scientists are able to study ancient air trapped in ice to gauge past centuries’ levels of CO2. Over the last 800,000 years of measurements, the carbon dioxide in the air never rose above three-hundredths of one percent. This changed at the turn of the 20th century, where CO2 levels began to rise. And this increase hasn’t stopped, with levels currently 40% higher than before the Industrial Revolution as our coal, oil and gas consumption releases carbon dioxide faster than Earth can absorb it.
As a result, CO2 builds up in the atmosphere and our Earth heats up. And while Venus is an extreme example of a planet overtaken by greenhouse gases, our planet is moving in that direction. Venus never had a chance to sustain human life, but Earth’s climate change is far from unstoppable. The decisions made by future generations will dictate if – or when – Earth will meet that fate.
Don’t miss an all-new COSMOS tonight at 9P.