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.
Total warming and trends. The global average and combined land and ocean surface temperature, show a warming of 0.85 [0.65 to 1.06] Â°C, in the period 1880 to 2012, based on multiple independently produced datasets. This gives a trend of 0.064 Â± 0.015 Â°C per decade over that period.