We compare existing observed data on variations in Northern Hemisphere sea ice and snow cover areas with those from equilibrium and transient the GFDL climate model runs. We find that Northern Hemisphere sea ice area has been decreasing during the last two decades. The observed trend and interannual variability of sea ice area are in a good agreement with the GFDL (aerosol + 1%/yr CO2) scenario of global warming, but the observed trend does not exceed the limits of its natural variability. Northern Hemisphere snow cover area has also been decreasing during the last two decades. The observed trend and interannual variability of snow cover area are almost twice as large as those in the GFDL (aerosol + 1%/yr CO2) scenario of global warming. There is a very low probability that the observed Northern Hemisphere snow area trend is a result of natural climate variability. Seasonal distributions of the observed trends in Northern Hemisphere sea ice and snow cover areas are significantly different from the model predicted scenario of global warming.