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 (1 - 1750) is reported.


Value:		≈ 700 parts per billion see this value in other units This is equivalent to... ≈ 7.0 × 10^-7 mol CH₄ mol^-1 air
HuID:		21785
Relevant Year(s):		1 - 1750
Summary:		Pre-industrial concentration of atmospheric methane (CH₄), inferred from ice core records. Here, pre-industrial is defined as any time in the current era before year 1750. Data record is taken from the referenced publication, but builds on many prior original studies. The original studies are referenced in the primary source. Consult "Atmospheric CH₄ concentration" for atmospheric measurements since 1983.
Method:		Data presented are constructed as spline fits from Law Dome ice cores, firn air, and Cape Grim instrumental (de-seasonalised archive, in situ and flask) records of CH₄ concentrations for the past 2000 years. Measurement precision for the ice core air samples is 4.1 ppb CH₄. Measurement precision for the firn air samples is 2 ppb CH₄.
Source:		MacFarling Meure, C., D. Etheridge, C. Trudinger, P. Steele, R. Langenfelds, T. van Ommen, A. Smith, and J. Elkins. The Law Dome CO2, CH4 and N2O Ice Core Records Extended to 2000 years BP. Geophysical Research Letters (2006)
Dataset:		Ice core measurements of CO2, CH4 and N20 atmospheric concentration (/ice_core_measurements_co2_ch4_n2o.csv) global resolution
Trend:
Original Data License:		CC-BY 4.0
Added By:		ilopezgo