The land and oceans make up about 29 percent of the planet. That mix is important for habitability. It tells us about exoplanet habitability.
There are a lot of places on the planet where life is present. Abundance of liquid water, plate tectonics, bulk composition and proximity to the Sun are some of the factors that contribute to our planet's habitability.
The ratio of oceans to land is a topic of discussion.
At this point, our understanding of habitability is not very good. We rely on the zone around the stars to find planets. It is based on the potential for liquid water on planets and is easy to determine from a long way away.
We know that factors that play a role in habitability include plate tectonics, bulk composition, a magnetosphere, atmospheric composition and pressure.
What about the ratio of oceans to land?
There is a new study looking at that ratio. A paper titled "Land Fraction Diversity on Earth-like Planets and Implications for their Habitability" has been submitted to the journal Astrobiology. Peer-reviewed hasn't been done yet.
Dennis Hning is one of the authors. The interface between planetary physics and Earth System sciences is the focus of Hning's research.
The International Space Science Institute is located in Bern. The heat flow and physical properties package was the principal investigator.
The root of the problem is plate tectonics. The plates on the surface of the Earth move along the mantle.
There is still a lot that scientists don't know about plate tectonics.
The conveyor belt principle is an important factor in plate tectonics. Sea-floor spreading is when plates are subducted into the mantle at convergent plate boundaries. Earth's land-to-ocean ratio is not different.
Other factors are also consistent with that ratio. Habitability is good for those factors. Nutrition is one of those things.
The land is exposed to weathering, which causes it to lose some of its structural integrity. The continental shelves are rich in flora and fauna. The run-off from the continents ends up on the shelf. Most of Earth's energy is contained in the continents and their shelves.
Habitability and plate tectonics are affected by heat. Earth has a blanket over it's mantle that helps keep it warm. The blanket effect is affected by the radioactive elements in the mantle.
The continents' blanket effect traps heat created by the decay of elements in the mantle.
The elements are brought to the crust where their heat is less efficient.
Life is dependent on the carbon cycle. The land-to-ocean ratio is one of the factors affecting that cycle. The weathering of continents removes carbon from the atmosphere in a way similar to the carbon emissions from the mantle by volcanoes.
Water is found in the mantle. The mantle's resistance to flow is lowered by the amount of water in the mantle. There is a feedback loop with mantle temperature. The more water enters the mantle, the easier it is to flow. More heat is released from the mantle.
The paper says that all of these factors are related in some way.
Habitability is created by the combination of these factors and others. If the Earth's ratio of land to water were skewed towards more land, the climate would be dryer, the continents would be cold, and the biosphere would not be large enough to produce an oxygen-rich atmosphere.
If there was more water, there could be less continental weathering. The oxygen-rich atmosphere needed for complex life and a richer biosphere can't be produced because of the lack of nutrients.
It's not possible to model all of Earth's tectonics. Many of the details have not been reached by scientists. Researchers don't know much about it. There's not enough evidence to make a solid conclusion.
Scientific modeling was used to understand how planets have different land to ocean ratios.
The three main processes that create the land-to-ocean ratio are growth of continental crust, exchange of water between the reservoirs on and above the surface and cooling.
The paper came from.
The processes are linked through the mantle and plates.
The spread of continental coverage on Earth-like planets is determined by the strengths of positive and negative feedback in continental growth and the relationship between thermal blanketing and radioactive isotopes upon the growth of the continental crust.
The main uncertainty in the model is in the parameters.
There will be feedback loops on every planet. It's difficult to quantify the relative strength of these loops. There are a lot of factors that affect the population of exoplanets.
This research is based on the feedback loops between all the factors and whether they're positive or negative.
A single stable present-day value of the continental surface area is implied by strong negative feedback.
Positive feedback loops can make a difference. The outcome of the evolution may be different depending on starting conditions and the early history.
Do the same feedback loops affect exoplanets? Is there an equilibrium between land and ocean coverage? Will a planet roughly Earth-sized and with a similar heat budget end up like Earth?
The research shows that both land and ocean planets are possible. Mixed planets like Earth are1-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-6556
Land planets are the most likely outcome according to a previous paper. Ocean planets are the most probable outcome.
There are uncertainties and a lack of data in this work, according to the authors. Their work sheds light on how different ratios of land to ocean are created.
They admitted to lacking data for a detailed understanding of quantitative differences in their discussion.
Other researchers have dealt with this issue as well. The study looked at planets around M-dwarfs, the most common type of star in the Milky Way, and where we are likely to find the most exoplanets.
The study found a similar distribution of emerged land area with the most planets either having their surface completely covered with water or with less surface water than Earth.
The study looked at more than continental growth.
What is the meaning of this study? What's the best mix of oceans to land for a Habitable Planet?
We could be living on the answer as it sounds.
This article was published in the past. The original article is worth a read.
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