What would happen if the oceans disappeared?

On the bright side: We wouldn't have time to miss the dolphins. On the downside: We'd be far too occupied trying to survive a planet consumed by flames. Imagining Earth without water, it's difficult to focus on anything else.

The oceans are crucial to supporting life on Earth — they may even be essential for evolution on any planet. [source: Cullum]. This raises a critical question: Without the oceans and deep ocean trenches that play such an essential role in our environment, how would our planet manage?

The Vital Role of Earth's Oceans

The oceans serve two essential functions for life. First, they absorb and redistribute solar energy. Without this water, the sun's intense heat would scorch the equator while leaving the poles largely unaffected, especially in winter.

Thankfully, water excels at absorbing energy, and oceans play a pivotal role in regulating Earth's temperatures. Ocean currents carry warm tropical waters toward the poles, while colder waters return to the equator, ensuring that no region becomes too extreme for life to endure while also warming colder zones.

Secondly, oceans are central to the water cycle — the continuous movement of water between the sea, atmosphere, and land. Water evaporates at the equator, forming clouds, and as the warm air rises, it draws cooler air from below.

This process fosters a more even distribution of heat, transforming areas that would otherwise be inhospitable into fertile, mild landscapes. For example, the Mediterranean's temperate climate and the palm trees thriving in parts of Scotland, warmed by the Gulf Stream, are direct results of this phenomenon.

What Would Happen if the Oceans Vanished?

Now, let’s return to our thought experiment: what if the oceans simply disappeared? Imagine that the oceans have turned into dry land. To keep the scenario somewhat realistic, we’ll assume the dirt remains moist enough to prevent the planet from becoming a giant dust storm right away.

Even though the oceans are gone, there is still some water left on Earth. Let’s take stock of what we have. Ice caps, lakes, rivers (now flowing over vast stretches of dirt), and underground water are still present. Combined, these sources account for about percent of our current water supply, with the remaining 96.5 percent having vanished with the oceans. This is not enough to kick-start a healthy global water cycle, even if we were to melt the ice caps. (Around 68.7 percent of Earth’s fresh water is locked in glaciers, ice caps, and permanent snow, mostly in Antarctica [source: USGS]).

Without oceans to generate clouds, rainfall would become extremely rare, and Earth would gradually turn into a vast desert. Our lakes and remaining water supplies would dwindle year after year until nothing remains. At the same time, the ocean floor and mid-ocean ridges would be exposed to the atmosphere, potentially triggering major changes in Earth’s systems. These changes could affect everything from global temperatures to tectonic plate movement and volcanic activity.

Worse Than the Ice Age?

For a time, humans might manage to survive near their homes. Groundwater could still be tapped, and underground hydroponic farms might be set up. However, on the surface, plants and animals would begin to perish almost immediately. While trees can endure for a while without water, the increasing dryness would eventually lead to fires that could spread across continents.

This scenario presents a complex challenge for humanity: beyond the typical dangers of fire (such as the risk of burning to death), the raging blazes would release vast amounts of carbon dioxide into the already suffocating atmosphere, driving global warming into overdrive. For humans, life would become even less hospitable than it was during the Ice Age.

The relentless heat of the sun would scorch the equator, transforming it into an oven with no ocean currents to offer relief. Meanwhile, the greenhouse gases from global wildfires would trap the sun's energy near the surface. Although temperature fluctuations between day and night could create winds, the global average temperature would rise to 153 degrees Fahrenheit, rendering life impossible for all but the hardiest desert species [source: Philander].

Last Shelter... Antarctica?

Migration would become a necessity. Humanity's best hope would lie in the period when the Antarctic ice sheet remains intact, triggering massive migrations to the Southern Hemisphere. As the planet heats up and Earth’s surface becomes uninhabitable, humanity's efforts would be focused on harvesting Antarctic ice and storing it underground, where it could be shielded from the heat and evaporation.

We might attempt to create a self-sustaining biosphere underground, but the isolation of Antarctica would present a huge challenge. Simply reaching it would be difficult due to unpredictable sea levels. Upon arrival, survivors would face a flooded wasteland, with no infrastructure or resources—no mines, roads, or food. The chances of enough people surviving to complete such a project are slim. The few remaining would likely retreat into underground bunkers.

The situation would worsen rapidly. On the Earth's surface, all plant life would be extinguished. As the world burns, the atmosphere would lose more oxygen, potentially making it impossible for humans to breathe, even if they somehow managed to endure the extreme surface temperatures. The land would become scorched.

If humans could survive longer in Antarctic bunkers, there would be no way to restart the carbon cycle or bring temperatures back to livable levels. As we exhausted the limited resources we had brought with us to Antarctica, we would eventually die off. Earth's only survivors would be small colonies of chemosynthetic bacteria living in underground hot springs. Without oceans, all other life would perish.

The Woods Hole Oceanographic Institution

Thankfully, we aren't facing this potential extinction event without some monitoring. The Woods Hole Oceanographic Institution, a non-profit research organization based in Woods Hole, Massachusetts, is dedicated to studying oceans and marine life, and is also actively tracking the effects of global warming.

With research institutions like the Woods Hole Oceanographic Institution closely monitoring rising sea levels, ocean acidification, and shifts in ocean circulation, we can take comfort in the fact that some of the brightest minds in humanity are actively overseeing the situation.