Global temperature changes, computer artwork. Colour-coded globes showing a progression of changing global surface temperatures from 1880 to 2005, the warmest year on record. Dark red indicates the greatest warming and dark blue indicates the greatest cooling. The carbon dioxide level in the atmosphere was about 285 parts per million in 1880, the first year in the GISS temperature record. By 1960, the atmospheric carbon dioxide concentration, measured at NOAA's Mauna Loa Observatory, was about 315 parts per million. Today, that measurement exceeds 390 parts per million. Because of a rapid warming trend over the past 30 years, the Earth is now reaching and passing through the warmest levels seen in the last 12,000 years