Levels of methane (CH4) gas in the Earths atmosphere are continuing to rise, in figures that will be of concern to climate change activists.
The latest data released by the National Oceanic and Atmospheric Administration (NOAA)s Earth System Research Laboratory (ESRL) found that the global average of atmospheric methane rose by 11 parts per billion (ppb) to 1867ppb last year from 1856.6ppb at the end of 2017.
The figures come from the ESRLs regular summaries of annual increases in atmospheric methane, based on globally averaged marine surface data.
It is important to recognize that the initial, April estimate of the annual increase is likely to change significantly as more data are added to the analysis, the report reads.
That estimate will be updated in subsequent months as more samples are measured for CH4 and included in the analysis. By autumn of the following year the annual increase will typically converge toward a final value.
The figures continue a trend of growing methane levels from when the NOAA began keeping records in 1983.
Since that year, atmospheric methane has steadily risen from around 1630ppb to the latest estimate of 1867ppb.
The NOAAs data shows that atmospheric methane levels have started to rise at a faster pace over the last decade after initially slowing down at the start of the 21st century.
Along with CO2, methane is a greenhouse gas whose presence in the atmosphere is exacerbated by human activities such as farming and the burning of fossil fuels.
The rise in methane levels comes despite global efforts to tackle climate change through the likes of the Paris Agreement, to which 184 nations are now party.
A recent study by the Carnegie Institute for Science found that one party to the Agreement, China, is failing to walk the walk on methane emissions, as its methane emissions rose by 1.1 million metric tons (1.1 teragrams) per year between 2010 and 2015.
China is the worlds largest producer and consumer of coal, which is used to generate over 70% of the countrys electricity.
The country stated in its 12th Five Year Plan that it aimed to remove or convert 5.6 million metric tons of methane from its coal mines by 2015, but it appears to have failed to meet this target.
Chinas methane emissions have steadily increased each year since 2000, with its overall methane emissions increasing by 50% between 2000 and 2015.
This figure accounts for around a quarter of the total global increase in methane emissions over that five-year period.