Methane-led climate change explains early Mars’ wet spells

In its early history, Mars had abundant liquid water flowing freely in rivers and forming giant lakes. But around 3.6 billion years ago that all changed and Mars became the mostly cold, arid planet we know today. However, a series of wet spells during the red planet’s first 600 million dry years have mystified scientists. Now, US researchers propose that changes in Mars’ axial tilt could have caused its ice to melt, releasing the powerful greenhouse gas methane from frozen methane clathrates.¹