I thought Mars lost water and have thin atmosphere because of loss of its magnetic field.
Mars owes its dry and dusty appearance to its wispy atmosphere, less than 1 percent of the thickness of the Earth's. But it wasn't always that way: The Red Planet formerly had a much thicker atmosphere that probably allowed for liquid water on the surface, an atmosphere that was depleted when the planet's magnetic field faded away.
We are not losing it, it is changing polarity ("flipping"). It may be reduced for a short time while the flip happens. It has happened many times before.
Mars owes its dry and dusty appearance to its wispy atmosphere, less than 1 percent of the thickness of the Earth's. But it wasn't always that way: The Red Planet formerly had a much thicker atmosphere that probably allowed for liquid water on the surface, an atmosphere that was depleted when the planet's magnetic field faded away.
http://www.popularmechanics.com/science/space/moon-mars/what...