Mars is coming out of an extreme ice age, study finds

In a discovery that could shed new light on the past habitability of Mars and provide new insight into how to deal with the climate change problem back here on Earth, a team of researchers found evidence of an ice age recorded in the polar deposits of the Red Planet.

Writing in Friday’s edition of the journal Science, Dr. Isaac Smith, a postdoctoral researcher at the Southwest Research Institute (SwRI) in San Antonio, and his colleagues explained they analyzed radar data collected using the NASA Mars Reconnaissance Orbiter and found layered ice deposits around the planet’s north pole similar to those responsible for ice ages on Earth.

“We found an accelerated accumulation rate of ice in the uppermost 100 to 300 meters of the polar cap,” Dr. Smith said in a statement. “The volume and thickness of ice matches model predictions from the early 2000s. Radar observations of the ice cap provide a detailed history of ice accumulation and erosion associated with climate change.”

Ice ages on Mars, he explained, are driven by processes similar to such events on Earth: long-term cyclical changes in the planet’s tilt and orbit impacting how much solar radiation it receives at any given latitude. Much like Earth, Mars experiences not only annual rotation and seasonal cycles, but longer cycles which impact the distribution of ice as well, and these periods may be more pronounced on the Red Planet.

Findings will help with Mars exploration and climate science on Earth

The reason for this phenomenon, according to the SwRI team, is that the planet’s tilt can change by as much as 60 degrees over a span of several hundred thousand years. In comparison, Earth’s tilt varies by just two degrees over the same period of time. This increase variability plays a key role in determining how much sunlight reaches the surface at each latitude, and thus, how much ice forms at any particular location.

“Because the climate on Mars fluctuates with larger swings in axial tilt, and ice will distribute differently for each swing, Mars would look substantially different in the past than it does now,” explained Dr. Smith, who worked on the study alongside scientists from the University of Texas Institute for Geophysics and the McDonnell Center for the Space Sciences at Washington University in St. Louis. “Furthermore, because Mars has no oceans at present, it represents a simplified ‘laboratory’ for understanding climate science on Earth.”

Their measurements of ice thickness indicated that approximately 87,000 cubic kilometers of ice have accumulated at the Martian poles since the end of the last ice age nearly 370,000 years ago, and that the bulk of this ice accumulated at the planet’s north pole. If spread uniformly across the surface, this would be equal to a layer approximately 60 centimeters thick, the authors said. The results will help them better understand the history of polar deposit accumulation relative to the planet’s orbital eccentricity, axial tilt, and rotation around the Sun.

Furthermore, the findings will help improve efforts to better model the past and future climate of Mars by examining how ice moves from poles to mid-latitudes during climate cycles. Dr. Smith added that learning more about ice on Mars is “important to the future of human exploration of the Red Planet,” as locating potential sources of water on the planet’s surface would be “critical” to the long term survival of a Martian colony.

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Image credit: ESA/DLR/FU-Berlin

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