3.6 billion years ago, Mars underwent an abrupt transformation from a dry climate to a wet climate with intense water activity: water currents dramatically carved rivers and lakes across the Red Planet’s surface. Scientists have long been trying to understand the cause. A new study by Peter Buhler of the Institute of Planetary Sciences puts forward the paradoxical idea that climate cooling due to the collapse of Mars’ atmosphere may have caused the ice caps to melt and cause a global flood.
The Martian atmosphere, which was composed mostly of carbon dioxide, began to liquefy billions of years ago, and about 3.6 billion years ago, its layer became so thin that the gas froze and fell to the surface as dry ice.
A large ice sheet of water ice existed over the south pole of Mars by then. According to Buhler’s model, this layer of dry ice, like a thermal blanket, retained the heat rising from the planet’s interior. This caused some of the water ice under the dry layer to melt. This could have melted between 4% and 40% of the water ice supply, a volume corresponding to between 20% and 200% of the current amount of water near the surface of Mars.
The model suggests that such meltwater could have filled a huge crater known as the Argyre Basin, forming a giant body of water the size of the Mediterranean Sea. The system of rivers and lakes that fed on this water could extend from the south pole to the northern plains for a distance of almost 10,000 kilometers. To date, this hypothesis is the only one that can explain the filling of the Argyre Basin 3.65-3.68 billion years ago.
The emergence of the Argyre Lake may have triggered a hydrologic cycle that lasted about 230 million years until the gradual dissipation of carbon dioxide into space weakened the thermal effect of the dry ice. The water from the lake evaporated, condensed at the poles, and returned again, maintaining this cycle.
If scientists successfully conduct additional tests, our understanding of Mars will take a big leap forward, which could solve the mystery of whether life had time to form on the planet during this period.
We previously reported on how the Hubble telescope solved the mystery of the disappearing Martian water.
Provided by universetoday.com
