Long ago, all continents were crammed together into one large landmass called Pangea. Pangea broke apart about 200 million years ago, with the pieces floating on the tectonic plates – but not permanently. The continents will come together again in the deep future. And a new study, presented today in an online poster session at the American Geophysical Union meeting, suggests that the future arrangement of this supercontinent could have a dramatic impact on Earth’s habitability and climate stability. The findings also have implications for the search for life on other planets.
The study, which has been submitted for publication, is the first to model the climate on a supercontinent in the deep future.
Scientists aren’t sure what the next supercontinent will look like or where it will be located. One possibility is that in 200 million years, all continents except Antarctica could converge around the North Pole and form the supercontinent “Amasia”. Another possibility is that “Aurica” could originate from all the continents that converge around the equator in about 250 million years.
In the new study, researchers used a 3-D global climate model to simulate how these two landmass arrangements would affect the global climate system. The research was led by Michael Way, a physicist at NASA Goddard Institute for Space Studies, a subsidiary of Columbia University’s Earth Institute.
The team found that, by altering the atmospheric and ocean circulation, Amasia and Aurica would have completely different effects on the climate. The planet could eventually get 3 degrees Celsius warmer if the continents all converge around the equator in the Aurica scenario.
In the Amasia scenario, where the land is amassed around both poles, the lack of land between them disrupts the ocean conveyor that is currently transporting heat from the equator to the poles. As a result, the poles would be colder and covered with ice all year round. And all that ice would reflect heat into space.
With Amasia “you get a lot more snow”, Way explains. “You get ice caps and you get this very effective ice-albedo feedback, which tends to lower the planet’s temperature.”
In addition to colder temperatures, Way suggested that the sea level would likely be lower in the Amasia scenario, with more water in the ice sheets, and that the snow conditions could mean that not much land would be available for growing crops.
Aurica, on the other hand, would probably be a bit more beachy, he said. The land concentrated closer to the equator would absorb the stronger sunlight there, and there would be no polar ice caps reflecting heat from Earth’s atmosphere – hence the higher temperature on Earth.
While Way compares the shores of Aurica to the paradisiacal beaches of Brazil, “the interior would probably be quite dry,” he cautioned. Whether or not much of the land would be arable would depend on the distribution of the lakes and the types of rainfall patterns it experiences – details that the current paper does not address but that can be explored in the future.
The simulations showed that the temperatures accounted for liquid water on about 60% of Amasia’s land, as opposed to 99.8% of the Auricas – a finding that could inform the search for life on other planets. One of the main factors that astronomers look for when exploring potentially habitable worlds is whether or not liquid water can survive on Earth’s surface. In modeling these other worlds, they tend to simulate planets that are either completely covered by oceans, or whose terrain resembles that of the modern Earth. However, the new study shows that it is important to take into account landmass arrangements when estimating whether the temperature drops in the ‘habitable’ zone between freezing and boiling.
While it may take a decade or more for scientists to determine the actual distribution of land and sea on planets in other galaxies, the researchers hope that having a larger library of land and sea arrangements for climate modeling could be helpful in estimating of the potential habitability of neighboring worlds.
Hannah Davies and Joao Duarte from the University of Lisbon and Mattias Green from Bangor University in Wales were co-authors of this study.
Material provided by Earth Institute at Columbia University. Originally written by Sarah Fecht. Note: Content can be edited for style and length.