Out Of This World
UEA research on fundamental oceanic properties such as salinity brings us closer to understanding the climates of distant planets.
The number of planets being discovered outside our solar system is rapidly increasing but many might not sustain life because they are either too close or too far from their sun. Scientists determine a planet’s habitable zone based on its distance from the sun and temperatures at which it is possible for the planet to have liquid water.
Oceans have an immense capacity to control climate and help the surface temperature of a planet to respond slowly to seasonal changes. This helps to ensure that temperature variations across a planet are tolerable.
Traditional research into habitability of planets has simplified the role oceans have to play, but UEA research is showing just how vital they are to climate stability and habitability of these distant worlds.
Prof David Stevens, Dr. Manoj Joshi, and postgraduate student Jodie Cullum created computer simulation patterns of ocean circulations on hypothetical ocean-covered Earth-like planets with different rotation periods. The simulations showed that a greater number of planets could potentially be habitable than was previously thought.
Since this, the team have discovered more about distant planets. In 2016, they found that salt levels of oceans on distant Earth-like planets could potentially have a big effect on their climates. This research was led by the Centre for Ocean and Atmospheric Sciences at UEA.
The research found that circulation in very salty or fresh water extra-terrestrial seas would influence their temperatures, increasing the potential for habitability for alien life.
This was a ground-breaking discovery because until this, researchers had not considered that the seas on distant Earth-like planets might be significantly more or less salty than the oceans on Earth.
Prof Stevens from UEA Mathematics said: “The number of planets being discovered outside our solar system is rapidly increasing. Our research helps to answer whether or not these planets could sustain alien life.”
“We wanted to find out what might be happening on other planets which might appear superficially similar to earth, but where conditions such as salinity are radically different to our own planet.”
Dr Manoj Joshi, from UEA’s School of Environmental Sciences, said: “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 travelling towards the equator at depth.
“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 travelling 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."
Jodie Cullum, from UEA’s School of Mathematics, said: “Of course, on any given exoplanet, many other properties are likely to differ from their Earth-like values, some of which may also have a significant influence on ocean circulation - such as ocean depth or the location of continents.
“But this is important work which will help us better-understand the habitability of distant planets in more accurate detail than ever before.”