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.
1998 is currently tied with 2009 as the sixth warmest year on record. Overall, the global annual temperature has increased at an average rate of 0.07Â°C (0.13Â°F) per decade since 1880 and at an average rate of 0.17Â°C (0.31Â°F) per decade since 1970.