CH has been measured directly in the environment since the 1970s. The Earth's atmospheric methane concentration has increased 160% since preindustrial levels in the mid-18th century.
Long term atmospheric measurements of methane by NOAA show that the build up of methane nearly tripled since pre-industrial times since 1750. In 1991 and 1998 there was a sudden growth rate of methane representing a doubling of growth rates in previous years. The June 15, 1991 eruption of Mount Pinatubo, measuring VEI-6was the second-largest terrestrial eruption of the 20th century. In 2007 it was reported that unprecedented warm temperatures in 1998the warmest year since surface records were recordedcould have induced elevated methane emissions, along with an increase in wetland and rice field emissions and the amount of biomass burning.
Data from 2007 suggested methane concentrations were beginning to rise again. This was confirmed in 2010 when a study showed methane levels were on the rise for the 3 years 2007 to 2009. After a decade of near-zero growth in methane levels, "globally averaged atmospheric methane increased by [approximately] 7 nmol/mol per year during 2007 and 2008. During the first half of 2009, globally averaged atmospheric CH was [approximately] 7 nmol/mol greater than it was in 2008, suggesting that the increase will continue in 2009." From 2015 to 2019 sharp rises in levels of atmospheric methane have been recorded.
In 2010, methane levels in the Arctic were measured at 1850 nmol/mol which is over twice as high as at any time in the last 400,000 years. According to the IPCC AR5, since 2011 concentrations continued to increase. After 2014, the increase accelerated and by 2017, it reached 1,850 (parts per billion) ppb. The annual average for methane (CH) was 1866 ppb in 2019 and scientists reported with "very high confidence" that concentrations of CH were higher than at any time in at least 800,000 years. The largest annual increase occurred in 2021 with current concentrations reaching a record 260% of pre-industrialwith the overwhelming percentage caused by human activity.
In 2013, IPCC scientists said with "very high confidence", that concentrations of atmospheric methane CH "exceeded the pre-industrial levels by about 150% which represented "levels unprecedented in at least the last 800,000 years." The globally averaged concentration of methane in Earth's atmosphere increased by about 150% from 722 ± 25 ppb in 1750 to 1803.1 ± 0.6 ppb in 2011. As of 2016, methane contributed radiative forcing of 0.62 ± 14% Wm, or about 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases. The atmospheric methane concentration has continued to increase since 2011 to an average global concentration of 1911.8 ± 0.6 ppb as of 2022. The May 2021 peak was 1891.6 ppb, while the April 2022 peak was 1909.4 ppb, a 0.9% increase. The Global Carbon Project consortium produces the Global Methane Budget. Working with over fifty international research institutions and 100 stations globally, it updates the methane budget every few years.
In 2013, the balance between sources and sinks of methane was not yet fully understood. Scientists were unable to explain why the atmospheric concentration of methane had temporarily ceased to increase.
The focus on the role of methane in anthropogenic climate change has become more relevant since the mid-2010s.