Note on Calendars 🗓️

Though we primarily utilise the Gregorian calendar for consistency, our activities involve investigating alternative methods of organising recorded historical events as we strive to uncover fresh perspectives and approaches to understanding our world.

Gregorian Calendar · CE
Common Era

The Gregorian calendar, introduced by Pope Gregory XIII in October 1582, is the most widely used civil calendar worldwide. This solar-based calendar was developed as a refinement to the Julian calendar, with the aim of bringing the date of the spring equinox closer to March 21. It consists of 12 months, totalling 365 days in a common year and 366 days in a leap year.

· Learn more on Wikipedia: https://en.wikipedia.org/wiki/Common_Era

Holocene Calendar · HE
Holocene Era or Human Era

The Holocene calendar starts from the beginning of the Holocene epoch, approximately 10,000 years ago, and uses the current year of the Gregorian calendar as a reference point. For example, the year 2020 in the Gregorian calendar is the year 12,020 HE in the Holocene calendar. This is calculated by adding 10,000 years to the current year, reflecting the time since the start of the Holocene epoch, which is considered a significant milestone in human history due to the development of agriculture and the rise of civilization. It was proposed in 1993 by Cesare Emiliani, a geologist and paleontologist, as a way to better reflect the current geological epoch of the Earth

· Learn more on Wikipedia: https://en.wikipedia.org/wiki/Holocene_calendar

Anthropocene Calendar · AE
Anthropocene Event, Epoch, Era, or Eon — still debated

The Anthropocene calendar is a suggested alternative to the Gregorian calendar, commemorating the period since the onset of the Anthropocene Event. This event is characterized by a significant increase in the influence of industrial societies on Earth's ecosystems, with its inception proposed to be in 1945. For example, the year 2020 in the Gregorian calendar is the year 75 AE in the Anthropocene calendar.

· Learn more on our dedicated page 🌍⏳ Anthropocene.

Trends in Atmospheric CO2 · ppm
Parts per million

The ppm (parts per million) measure for CO2 represents the concentration of carbon dioxide molecules in the atmosphere, with one ppm indicating one molecule of CO2 for every million molecules of air. It serves as a globally significant variable, and thus, it can be employed as a temporal metric. The Keeling Curve, which displays the ongoing rise in atmospheric CO2 concentrations, is primarily measured at the Mauna Loa Observatory in Hawaii.