These are the total yearly methane (CH4) emitted through human activities expressed as weight in teragrams. In the scientific literature, these are referred to as anthropogenic emissions. Examples of human emissions include rearing livestock and fossil fuel emissions, and there are other sources that you find in the next breakdown chart.Wikipedia: Methane Emissions
The unit teragram describes the average weight of atmospheric methane per year.Wikipedia: Teragram
There is overall a growth in human methane emissions over time.
The underlying data source provides only average methane emissions per decade, 2000 to 2009 and 2008 to 2017. Based on the decade data we can approximate for single years.
Here is an example of how human emissions relate to the whole picture of atmospheric methane: The atmospheric methane increase of 18.9 teragrams in 2017 is the sum of the human emissions of 380 teragrams plus the natural emissions of approximately 200 to 370 teragrams minus the natural sinks of approximately 550 to 625 teragrams in 2017.
Atmospheric increase = human emissions + natural emissions - sinks
Regarding the overall picture, the scientific community has high confidence in the atmospheric increase values and levels and reasonable confidence in the human emissions, but lower confidence in the natural emissions and natural sinks of methane.Wikipedia: Methane emissions
There is a very long delay in the data. This is because this data is produced periodically by a global research project where scientists contribute to a mutually agreed knowledge base. It takes a lot of time and effort to generate trustworthy data that we can be confident in.Global Carbon Project: Methane Budget
The Global Carbon Project has a Global Methane Budget besides its Global Carbon Budget. It calculates the budget using two approaches: top-down and bottom-up. We show the results from the bottom-up approach because this approach also contains a breakdown of the emissions. Feel free to also explore the Global Methane Budget from the top-down perspective in the following link.Global Carbon Project: Methane Budget
Global Carbon Project: Global Methane Budget 2020 Global Methane Budget 2020
Credits: Saunois, M. et al (2020) - full reference belowUpdate cycle: unknownDelay: unknownReference: Global Methane Budget 2000-2017: Saunois, M., Stavert, A. R., Poulter, B., Bousquet, P., Canadell, J. G., Jackson, R. B., Raymond, P. A., Dlugokencky, E. J., Houweling, S., Patra, P. K., Ciais, P., Arora, V. K., Bastviken, D., Bergamaschi, P., Blake, D. R., Brailsford, G., Bruhwiler, L., Carlson, K. M., Carrol, M., Castaldi, S., Chandra, N., Crevoisier, C., Crill, P. M., Covey, K., Curry, C. L., Etiope, G., Frankenberg, C., Gedney, N., Hegglin, M. I., Höglund-Isaksson, L., Hugelius, G., Ishizawa, M., Ito, A., Janssens-Maenhout, G., Jensen, K. M., Joos, F., Kleinen, T., Krummel, P. B., Langenfelds, R. L., Laruelle, G. G., Liu, L., Machida, T., Maksyutov, S., McDonald, K. C., McNorton, J., Miller, P. A., Melton, J. R., Morino, I., Müller, J., Murgia-Flores, F., Naik, V., Niwa, Y., Noce, S., O'Doherty, S., Parker, R. J., Peng, C., Peng, S., Peters, G. P., Prigent, C., Prinn, R., Ramonet, M., Regnier, P., Riley, W. J., Rosentreter, J. A., Segers, A., Simpson, I. J., Shi, H., Smith, S. J., Steele, L. P., Thornton, B. F., Tian, H., Tohjima, Y., Tubiello, F. N., Tsuruta, A., Viovy, N., Voulgarakis, A., Weber, T. S., van Weele, M., van der Werf, G. R., Weiss, R. F., Worthy, D., Wunch, D., Yin, Y., Yoshida, Y., Zhang, W., Zhang, Z., Zhao, Y., Zheng, B., Zhu, Q., Zhu, Q., and Zhuang, Q.: The Global Methane Budget 2000–2017, Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2019-128, in review, 2019