Water once flowed across the Martian landscape, cutting the Grand Canyon-esque Nanedi Valles into the Red Planet's surface some 3.8 billion years ago.

These are the results of a new study that suggests greenhouse gases could have raised Mars' temperatures enough for liquid water to exist.

In the past, failed efforts to construct temperatures warm enough for liquid water relied on climate models that only accounted for carbon dioxide and water. Published in the journal Geosciences, the new study suggests that by throwing molecular hydrogen in the mix, the atmosphere would have produced the above-freezing temperatures necessary for the formation of rivers.

The study employs a one-dimensional climate model to show that the gases belched by the planet's volcanism would have seeded the atmosphere with the hydrogen and carbon dioxide needed to trigger a greenhouse gas effect capable of raising temperatures, despite the Sun being an estimated 30 percent dimmer at the time.

Another option, according to the researchers from Pennsylvania State University, is that the Martian valleys were created after massive meteorites pummeled the planet, generating steam atmospheres that rained out. However, the scientists note this method would not have been able to produce the volumes believed to have been necessary to carve the network of valleys seen on Mars' surface.

"We think that there is no way to form the ancient valleys with any of the alternate cold early Mars models," doctoral student Ramses Ramirez said in a statement. "However, the problem with selling a warm early Mars is that nobody had been able to put forth a feasible mechanism in the past three decades."

Ramirez said he hopes the new findings will help change people's minds on the subject.

"This is exciting because explaining how early Mars could have been warm and wet enough to form the ancient valleys had scientists scratching their heads for the past 30 years," Ramirez said. "We think we may have a credible solution to this great mystery."