Scientists have discovered the type of circulation that oceans may experience, which could help them pinpoint which planets are more likely to harbor life.
Most computer simulations of habitable climates focus on the atmosphere of the planet. However, understanding the ocean is also crucial for understanding whether or not a climate is stable enough to host life.
"The number of planets being discovered outside our solar system is rapidly increasing," said David Stevens from the University of East Anglia's School of Mathematics and one of the researchers. "Our research helps to answer whether or not these planets could sustain alien life. We think that many planets may be uninhabitable because they are either too close or too far from the sun. A planet's habitable zone is based on its distance from the sun and temperatures at which it is possible for the planet to have liquid water."
In this case, the researchers wanted to find out what might be happening on other planets that are, at a glance, similar to Earth. These planets, however, may have different salinity levels. This could drastically impact the climates on these particular planets.
In this latest study, the researchers used computer models in order to determine the ocean circulation on distant planets. They then looked at what the simulation did when the ocean had different levels of salinity in comparison to Earth. More specifically, they looked at oceans with very low salinity and salinity that was similar to the average value of Earth's oceans.
"On Earth, we have a circulation where warm water moves towards the poles at the surface, before being cooled, then sinking at high latitudes and traveling towards the equator at depth," said Manoj Joshi, one of the researchers. "Our research shows that oceans on other planets with a much higher salinity could circulate in the opposite direction - with polar water flowing towards the equator at the surface, sinking in the tropics and traveling back towards the poles at depth. We also found a similar pattern emerging for freshwater oceans. These circulation patterns are the opposite of what happens on Earth, and would result in a dramatic warming in the polar regions. Such a circulation scenario might extend the planet's range of habitability."
The findings reveal a bit more about exoplanets. This is particularly important when considering how many planets are being discovered every day. By narrowing them down, researchers can focus on which ones are most likely to support life.
The findings were published in the Proceedings of the National Academy of Sciences' April journal.
