The surface of Mars displays evidence of past fluvial activity. Climate scientists have long struggled to explain how water could have remained liquid long enough to carve fluvial features because models of the early martian climate typically do not produce mean annual temperatures in excess of freezing. A new model by Ashley Palumbo and colleagues suggests that transient, seasonal high temperatures on Mars could have been enough to produce local melting, as observed in the Antarctic McMurdo dry valleys. This transient melting could have produced enough water flow to account for carving of the martian valley networks. READ MORE