A: Yes, it is an unequivocal fact that the Earth’s average temperature continues to rise, despite some natural year-to-year fluctuations. The hottest 10 years on record have all taken place in the past dozen years. Each of the past three decades has been substantially warmer than the decade prior to it.
All analyses of all surface temperature data sets compiled by major climate centers around the world show a clear warming trend. Besides these thousands of thermometer readings from weather stations around the world, there are many other clear indicators of global warming such as rising ocean temperatures, sea level, and atmospheric humidity, and declining snow cover, glacier mass, and sea ice.
Because temperatures vary from year to year, scientists measure trends in running averages and analyze trends over decades rather than expecting every year to be hotter than the previous year. Some years have particular factors that make them hotter than those just before and after. For example, a major El Niño event combined with the persistent rise in heat-trapping gases made 1998 one of the hottest years on record. That has caused some people to claim that Earth has been “cooling” since then. But as the data clearly show, this claim is false.