<sup>14</sup>C Trends: Going Backwards in Time | Scripps CO2 Program

14C Trends: Going Backwards in Time


Measured 14C/C in atmospheric CO2 over 1950-2015 from a compilation[1] and from individual samples over 2014-2021 from sites[2] in the Northern Hemisphere (La Jolla at 32°N and Mauna Loa at 20°N) and the Southern Hemisphere (Samoa at 14°S and South Pole at 90°S). The compilation combines various data sources and is representative of tropical regions[1]. Data are reported with typical normalization and correction[3]. Preliminary data from individual samples are shown for 2014-2021, data are publicly available at https://scrippsco2.ucsd.edu/ after quality control.

Please cite as: Graven, H, R Keeling and X Xu, 2022. Radiocarbon dating: Going back in time. Nature.

The Scripps CO2 program has been supported by a series of grants from U.S. NSF, DOE, NOAA, and NASA, most recently by OPP-1922922, NNX17AE74G, and the Schmidt Futures Program. These 14C measurements were supported by NASA and the Leverhulme Trust.


  1. Graven, H., et al., Compiled records of carbon isotopes in atmospheric CO2 for historical simulations in CMIP6. Geosci. Model Dev., 2017. 10(12): p. 4405-4417.
  2. Graven, H.D., T.P. Guilderson, and R.F. Keeling, Observations of radiocarbon in CO2 at seven global sampling sites in the Scripps flask network: Analysis of spatial gradients and seasonal cycles. J Geophys Res, 2012. 117(D2): p. D02303.
  3. Stuiver, M. and H.A. Polach, Discussion: Reporting of 14C Data. Radiocarbon, 1977. 19(3): p. 355-363.

Data sharing policy

The data and graphics on this website are made freely available, with the understanding that appropriate credit will be given. For applications supporting peer-reviewed scientific publications, coauthorship may sometimes be appropriate. An example would be if an important result or conclusion depends on this product, such as the first account of a previously unreported phenomenon. Ethical usage requires disclosing intentions at early stages of the work in order to avoid duplicating ongoing studies at Scripps. For applications where coauthorship is not needed, which includes all applications outside of the peer-reviewed scientific literature, it is sufficient to acknowledge the Scripps CO2 program as the source. Please direct queries to Ralph Keeling (rkeeling@ucsd.edu)