The climate of early Mars is a subject of debate. While it has been thought that Mars had a warm and wet climate like Earth, other researchers have suggested early Mars might have been largely glaciated. A recent study by Ramses Ramirez from the Earth-Life Science Institute (Tokyo Institute of Technology, Japan) and Robert Craddock from the National Air and Space Museum’s Center for Earth and Planetary Studies (Smithsonian Institution, U.S.) suggests that the early Martian surface may not have been dominated by ice, but might instead have been modestly warm and prone to rain, with only small patches of ice.