Cesare Emiliani's proposal for a calendar reform sought to solve a number of alleged problems with the current Anno Domini era, which number the years of the commonly accepted world calendar. These issues include:
- The Anno Domini era is based on an erroneous estimation of the birth year of Jesus. The era places Jesus's birth year in AD 1, but modern scholars have determined that he was likely born in or before 4 BC. Emiliani argued that replacing it with the approximate beginning of the Holocene makes more sense.
- The reported birth of Jesus is a less universally relevant epoch event than the approximate beginning of the Holocene.
- The years BC are counted down when moving from past to future, making calculation of time spans difficult.
- The Anno Domini era has no year zero, with 1 BC followed immediately by AD 1, complicating the calculation of timespans further.
Instead, HE uses the "beginning of human era" as its epoch, arbitrarily defined as 10,000 BC denoted year 1 HE, so that AD 1 matches 10,001 HE. This is a rough approximation of the start of the current geologic epoch, the Holocene (the name means entirely recent). The motivation for this is that human civilization (e.g. the first settlements, agriculture, etc.) is believed to have arisen within this time. Emiliani would later propose that the start of the Holocene be fixed at the same date as the beginning of his proposed era.
Human Era proponents claim that it makes for easier geological, archaeological, dendrochronological and historical dating, as well as that it bases its epoch on an event more universally relevant than the birth of Jesus. All key dates in human history can then be listed using a simple increasing date scale with smaller dates always occurring before larger dates. Another gain is that the Holocene Era starts before the other calendar eras. So it could be useful for the comparison and conversion of dates from different calendars.
When Emiliani discussed the calendar in 1994 he mentioned that there was no agreement on the date of the start of the Holocene era, with contemporary estimates ranging between 12,700 and 10,970 years BP. Since then, scientists have improved their understanding of and can now more accurately date the beginning of the Holocene. A consensus viewpoint has solidified and was formally adopted by the IUGS in 2013. Current estimates place its start at 9701 BC, about 300 years more recent than the epoch of the Holocene calendar.