Records from land stations and ships indicate that the global mean surface temperature warmed by between 1.0 and 1.7°F since 1850. These records indicate a near level trend in temperatures from 1880 to about 1910, a rise to 1945, a slight decline to about 1975, and a rise to present. The Intergovernmental Panel on Climate Change (IPCC) concluded in 2007 that warming of the climate system is now “unequivocal,” based on observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level. Since the mid 1970s, the average surface temperature has warmed about 1°F. The Earth’s surface is currently warming at a rate of about 0.32ºF/decade or 3.2°F/century. The eight warmest years on record (since 1850) have all occurred since 1998, with the warmest year being 2005. The warming trend is seen in both daily maximum and minimum temperatures, with minimum temperatures increasing at a faster rate than maximum temperatures. Land areas have tended to warm faster than ocean areas and the winter months have warmed faster than summer months. Widespread reductions in the number of days below freezing occurred during the latter half of the 20th century in the United States as well as most land areas of the Northern Hemisphere and areas of the Southern Hemisphere. Average temperatures in the Arctic have increased at almost twice the global rate in the past 100 years.