An international team of researchers working for the Global Carbon Project has found that global methane emissions increased by 9% (or approximately 50 million tons) between 2000-2006 and 2017, and that manmade emissions are responsible for the majority of this increase.
According to a new Global Carbon Project report, unless urgent action is taken to mitigate methane in the coming few years, this trend will lead us to future scenarios that are incompatible with the objectives of the Paris Agreement.
After a period of stabilization in the early 2000s, international measurement networks have been observing a further and ongoing increase in methane concentrations, which started accelerating since 2014. Concentrations are currently increasing at a rate of around 8-12 parts per billion (ppb)/year.
In 2017 and 2018, methane growth rates in the atmosphere were around 8.5 and 10.7 ppb/year, which makes them among the strongest years since 2000.
Methane (CH4) is the second most abundant anthropogenic greenhouse gas after carbon dioxide (CO2) and its warming effect is 28 times greater per kilogram than that of CO2 over a 100-year period. Since the start of the industrial revolution, atmospheric methane concentrations have increased more than two and a half times. The cause of this increase in emissions is largely linked to human activities.
Methane emissions also differ across regions: 60% of the increase in methane emissions can be attributed to tropical regions, and the rest to mid-latitudes.
In the Arctic, rising temperatures are causing the northern permafrost to melt and creating thaw lakes, which according to model results would translate into increased methane emissions in the 21st century. However, the researchers conclude that methods based on measurements of atmospheric concentrations do not yet detect a signal in this direction.
The three regions mainly responsible for the increase are Africa, Asia, and China, each with an increase of 10-15 Mt. North America would contribute around 5-7 Mt, whereof 4-5 Mt originates from the United States.
Africa and Asia (excluding China) are main contributors to the increase in emissions from the agriculture and waste sectors. For China and North America, growth in emissions from the fossil fuels sector is the most significant.
Europe is the only region in the world where emissions seem to have decreased: between -4 and -2 Mt, depending on the estimation method used. This decrease is mainly related to developments in the agricultural sector and to the diversion of waste away from landfills.