By 1990 the average atmospheric pressure on Mars has increased to 650 millibar. This is roughly twice the pressure seen at the top of Mt. Everest on Earth. While still thin and extremely cold for human life ( the percentage of atmospheric oxygen stands at just under 10% and the daytime surface temperature averages 10 degrees Fahrenheit - at mid-latitudes - during the summer months ), the atmosphere of Mars now performs four important functions:
      The surface is now shielded in some measure from UV rays
      The thickening atmosphere is enabling the surface to retain and trap infrared heat
      Humans - for surface travel - can shed heavy pressure suits in favor of thermal cloating and supplamental oxygen supplies
      Propellor driven flight is now possible.