The Human Impacts Database

A collection of useful numbers for quantifying the impacts of the human presence on Earth.

This quantity comes from a time series measurement and the most recent value (2021) is reported.


Value:		≈ 1900 parts per billion see this value in other units This is equivalent to... ≈ 1.90 parts per million ≈ 1.90 × 10^-6 mol CH₄ mol^-1 air
HuID:		44953
Relevant Year(s):		2021
Summary:		Globally-averaged atmospheric methane (CH₄) concentration determined from marine surface sites from 1983 to the present day. Global averages are important for methane concentrations, as concentration can vary substantially between sites (e.g. Southern Hemisphere vs Northern Hemisphere, as shown in Figure 6.3. of Chapter 6 of the 5th IPCC report).
Method:		The Global Monitoring Division of NOAA’s Earth System Research Laboratory has measured methane since 1983 at a globally distributed network of air sampling sites. A global average is constructed by first smoothing the data for each site as a function of time, and then smoothed values for each site are plotted as a function of latitude for 48 equal time steps per year. Global means are calculated from the latitude plot at each time step. The 95% confidence interval in monthly measurements is about ±2 part per billion, which is small compared to seasonal and annual changes in the concentration (see trend).
Source:		NOAA ESRL Global Monitoring Laboratory Trends in Atmospheric Methane. (2021)
Dataset:		Globally-averaged, monthly mean atmospheric CH4 concentrations (monthly_global_ch4_data_processed.csv) global resolution
Trend:
Added By:		ilopezgo