If there was a majority of land on earth (66 percent land), how would it affect the animals and plant? Lets say somehow earth has been created with 66 percent land and 34 percent water? Would our planet still have life? How would it affect our ancestors? The would be less sea life creatures I guess.

  • $\begingroup$ Cool question, but why would there be less life? $\endgroup$
    – HDE 226868
    Dec 12, 2014 at 2:21
  • $\begingroup$ @HDE226868 less water for plants and animals. $\endgroup$ Dec 12, 2014 at 2:22
  • $\begingroup$ Okay, I see now. $\endgroup$
    – HDE 226868
    Dec 12, 2014 at 2:23
  • $\begingroup$ Not necessarily, if the water is equally spread out it would give plenty of precipitations but that is unlikely to happen. $\endgroup$
    – Vincent
    Dec 12, 2014 at 2:30
  • $\begingroup$ Also there might be less diversity, because there would probably be less endemic land organisms as the continents will have a bigger chance to be connected. On the other hand you might have separated oceans which in turn would give you more endemic water organisms. $\endgroup$
    – drat
    Dec 12, 2014 at 6:09

7 Answers 7


A planet with less surface water would probably have less atmospheric water as well. The total volume of water on the planet isn't necessarily lower on such a planet because the oceans, though covering fewer square miles, might be deeper than those on Earth. Still, the amount of water which would evaporate from exposure to sunlight and wind, would be less because less surface water would be present to be exposed.

So, it would have a drier atmosphere, but might not be a desert. If major portions of the land's surface was made from porous sedimentary rock and dirt, and if the average water table was very near the surface, then plants might evolve with deeper root systems to get from the depths, what the sky could not provide.

Once you have abundant plants to bring the water to the surface, it is possible that land based animal life could florish. From there, things could possibly work out as they did here.

I don't think anybody knows enough in all the relevent sciences to definitively say what affect more land would have on the evolution of intelligent life. I don't think we truely know how it happened here, so the wise voice on that matter is silent. If however, you somehow got your planet populated with intelligent life, it would probably be even more dependent on coastlands and rivers than we were (simply because of their scarcity). In the end, you might end up with a lot more vacant land, but not necessarily more usable vacant land.


One major effect that the oceans have - as we have seen over the last twenty years or so - is that they are a powerful climatic stabiliser. They behave like a huge battery for thermal energy, both in terms of absorbing and holding it - as we're seeing now - and in terms of moving it around and releasing it, which is Western Europe is fairly warm for its latitude thanks to the North Atlantic Conveyer. Having a smaller amount of ocean would be likely to affect that stability so that other environmental changes from volcanism, meteor impact or human action might have a stronger and more rapid effect.

As other answers mention, conditions may be similar to the last ice age with frozen poles and an uninhabitable equatorial region pushing life into narrower temperate bands. If your land is bunched together you might expect to see something like the Pangean Megamonsoon where there was a seasonal reversal of prevailing winds resulting in clear seasonal differences in rainfall on different sides of the continent. Either way, you might anticipate that you would have very arid hinterlands where clouds tend to form over the ocean but they empty of rain before they reach the central areas, especially if you have mountain ranges between there and the coast. You might look at central Australia for the type of ecosystem this would result in for warmer climes.

  • $\begingroup$ This is probably the biggest noticeable change. $\endgroup$
    – Adam Davis
    Dec 12, 2014 at 15:15

It wouldn't really change that much as far as biology is concerned. The basic reason is that planets are really REALLY big in relation to most lifeforms. So even if say half the planet would be desert, the area of fertile coastal areas would still be very large in relation to what ground animals need to survive. And 34% ocean is actually not that different from 75% ocean from the viewpoint of a fish, huge is huge.

The issue here is that all square kilometers are not created equal. Most life would exist in coastal areas; ocean where coastal upwellings make algae bloom, land where the rains coming from the sea make plants thrive. So the ratio of open ocean to open central plains is not really that big a deal for biosphere.

There is actually large effect from continents on biosphere, but it is more a matter where the continents are and how they are shaped, than of the absolute amount. For example, while having less oceans in general makes the planet more arid, a planet with lots of small narrow oceans in the tropics could have more rain falling on land than Earth does. The percentage of ocean cover affects the amount of rain falling directly on ocean just as much as it affects evaporation.

I presume that having land dominated planet would increase the likelihood of certain types of extreme events, but Earth has undergone pretty extreme events as well, so it is not obvious how this would change things. This also suffers from the issue of scale, compared to the geological scale the evolutionary scale is much smaller, so the biosphere would adapt to the current situation fast enough and the historical effects of having more land has on different events would be obscured.


I watched this on discovery channel Neil Degrasse Tyson talking about the the comparison between Venus and Earth, the oceans, formation of limestone and how that was responsible for removing Carbon Dioxide ejected in large quantities by volcanic eruptions.


Venus and Earth started out with about the same amount of carbon, but the two worlds were propelled along radically different paths, and carbon was the decisive element in both stories.

On Venus, Carbon Dioxide all in the form of gas-- carbon dioxide-- in the atmosphere. Most of the carbon on Earth has been stored for eons in solid vaults of carbonate rock, like part of a chain that forms the celebrated White Cliffs of Dover, right on the English Channel.

Created over the eons by Trillions of one-celled algae

Volcanoes supply carbon dioxide to the atmosphere, and the oceans slowly absorb it. Working over the course of millions of years, the microscopic algae harvested the carbon dioxide and turned it into these tiny shells. They accumulated in thick deposits of chalk, or limestone, on the ocean floor.

...Later, the restless Earth pushed up the seafloor and carved out these massive cliffs. Other marine creatures took in carbon dioxide to build enormous coral reefs. And the oceans converted dissolved CO2 into limestone even without any help from life. As a result, only a trace amount was left as a gas in Earth's atmosphere. Not even three-hundredths of one percent.

Think of it-- fewer than three molecules out of every ten thousand. And yet, it makes the critical difference between a barren wasteland and a garden of life on Earth.

With no CO2 at all, the Earth would be frozen.

And with twice as many, we're still talking about only six molecules out of ten thousand. Things would get uncomfortably hot and cause us some serious problems but never as hot as Venus; not even close.

That planet lost its ocean to space billions of years ago.

Without an ocean, it had no way to capture CO2 from the atmosphere and store it as a mineral.

The CO2 from erupting volcanoes just continued to build up. Today, that atmosphere is 90 times heavier than ours.

If your planet is relatively benign Volcano-wise then possible. Too many volcanic eruptions and you might have problems. For the early history of your world, one-celled algae will be the only life capable of removing the carbon dioxide ejected by volcanoes.


One effect I could imagine is that life would have entered land earlier in evolution, since there's less space in the upper ocean levels (the ones which are most life-friendly, because below there's no sunlight). Probably also the deep sea would be a bit more populated, but not much because there's still the energy limitation (and the total energy the ocean gets is still proportional to the water surface).

However a lot depends also on how the water is distributed. If the water is mostly near the equator, a lot more water life can be supported than is the water is mostly near the poles.

As Henry Taylor already mentioned, the planet would likely have drier land. Not only because less water surface means less evaporation, but also because more land area means that the evaporated water would be distributed over a larger area, and a lot of the area would be further away from the water. Note, however, that this is an average; certain areas could still be quite wet (especially near the ocean, or at mountains where there's typically wind coming from the ocean). I'd expect there to be large deserts in the middle of the land.

A larger part of the land would have continental climate as opposed to maritime climate (obviously), with the corresponding vegetation.

Less water in the air also means less greenhouse effect, so the climate could on average also be a bit colder.

Of course a lot of this also depends on other factors; I was assuming a mostly earth-like planet, just with less oceans. Another option would be a hotter planet where the oceans are smaller because more of the water is in the air due to the high temperatures. Such a planet would, in opposition of the scenario described above, be very humid; probably most, if not all, of the land mass would be covered by rain forest (or that planet's equivalent).

Another reason for less water could be that the planet is so cold that most of the water exists as ice on the continents (a sort of an extreme ice age). In that case, most of the planet would have conditions like we know from the Arctic/Antarctic. Tropical conditions would be unheard of on that planet. This planet would be very dry because not only the water from the sea, but also from the air would be mostly bound in ice and snow.


Not being the same, we have suffered similar issues on Earth

On one side, we have had supercontinents where the climate conditions have been as extreme in their interiors as if there had been very few oceans on Earth.

Just to cite some phrases:

The albedo difference causes a shift in climate by onshore winds. "Continentality" occurs because the center of large continents are generally higher in elevations and are therefore cooler and dryer. This is seen today with Eurasia, and evidence is present in the rock record that this is true for the middle of Pangaea.


With less water providing less of a heat sink, and less rainfall to cool overly hot deserts, the day/night temperature differential will be significantly higher. This makes it harder for life to live on land, which means much less diversity, and probably none of the more complex large animals such as dinosaurs, birds, and mammals. Possibly not even reptiles. However, that wouldn't stop evolution from occurring in the seas.

Seasonal temperature variation will be greater, too. The biggest problem, and this was already touched on in someone else's response, is the much greater likelihood of a runaway climate change; either a hothouse earth or an iceball earth. In the former case, Earth winds up like Venus, and utterly lifeless; in the latter case, everything on the land bigger than a microbe dies, and so do all or nearly all freshwater species. Even marine species will have a great die-off, with the only survivors those which can under a layer of ice. Note the latter can happen repeatedly, with periods of warming in between. Contrariwise, the hothouse scenario is one one-way ticket. Once water vapor gets hot enough to disassociate into hydrogen and oxygen, the hydrogen will escape into space, and little would be left to form water even if things did cool off again.


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