Wash the thermometer in soap and rinse with cool, clean water before and after you use it. Do not use hot water because the thermometer may break. After washing, it is best to soak the thermometer in alcohol for 20 minutes. You can use ethyl, isopropyl, or medical alcohol (ethanol).
1 In 2015, the average temperature across global land and ocean surfaces was 1.62Â°F (0.90Â°C) above the twentieth-century averageâthe hottest year in the 136-year record.  Since 1976, every year has been warrmer than the long-term average.
The earth's average temperature rose by 0.8 Â°C (1.5 Â°F) during the last century. That change is in the mean global temperature that has been calculated for each year since 1880. The history of average global temperature is based on data gathered around the world at weather stations, on ships and by satellites.