2021 was the 10th consecutive year that carbon dioxide rose by more than two parts per million. With an increase of two-point-sixty-six ppm over the 2020 average
The atmospheric levels of methane and NOAA preliminary analysis results
In April 2022, the National Oceanic and Atmospheric Administration (NOAA) scientists released the results of their latest preliminary analysis regarding the atmospheric levels of methane.
The American scientific and regulatory agency that monitors climate, coasts, weather, and ocean and forecasts the weather announced that the analysis of the data from NOAA’s global sampling network revealed that in 2021 methane levels recorded the largest annual increase ever observed.
In 2021, atmospheric methane levels averaged 1,895.7 ppb, around 162 percent higher than the pre-industrial atmospheric methane levels. There are estimations that in 2021 global methane emissions were fifteen percent higher than in the period between 1984 and 2006.
A record annual increase in the atmospheric levels of methane. The second biggest contributor to anthropogenic global warming after carbon dioxide (CO2), has been observed by NOAA scientists for the second year in a row
In 2021, according to NOAA’s preliminary analysis, the annual increase in atmospheric methane was seventeen parts per billion (ppb). This is the largest annual increase since 1983 when systematic measurements began. The increase in atmospheric methane amounted to fifteen-point-three ppb during the previous year.
What is atmospheric methane?
The atmosphere is a layer of gases that envelopes planetary bodies. Such as the Earth, thanks to the gravitational attraction of the planets, which pulls the gases inward. The Earth’s atmosphere has several layers based on temperature, which go from the planet’s surface all the way to outer space.
Nitrogen (N2) and oxygen (O2) are the most common gases in the Earth’s atmosphere. In fact, the atmosphere is has seventy-eight percent nitrogen and around twenty-one percent oxygen. Other gases, such as argon, and carbon dioxide (CO2), are in the atmosphere in lower amounts. Among these other gases, there is atmospheric methane, the methane (CH4) present in Earth’s atmosphere.
«Atmospheric methane is a gas, and its molecule is CH4. It’s a greenhouse gas in the atmosphere, and it’s the second most potent greenhouse gas after carbon dioxide». Said Xin (Lindsay) Lan, a research scientist at NOAA’s Global Monitoring Laboratory and the University of Colorado Boulder.
How is methane different from other greenhouse gases? How does methane contribute to climate change?
Despite being low, its concentration levels in the planet’s atmosphere are relevant as atmospheric methane is a potent greenhouse gas that, like carbon dioxide (CO2), can trap heat in the atmosphere, causing global warming. Compared to the aforementioned greenhouse gas, methane is not as persistent, having an estimated GWP of between twenty-seven and thirty over 100 years (EPA).
Carbon dioxide pollution is the chief cause of anthropogenic climate change, accounting for about sixty-five percent of human-generated greenhouse gas emissions, while methane accounts for around sixteen percent (IPCC 2014).
Last year human activities emitted an estimated thirty-six billion tons of carbon dioxide into the atmosphere. During the same period, there was the emission of around 640 million tons of methane.
Methane is twenty-five times more potent at trapping heat in the atmosphere over a 100-year period, which gives it a robust short-term influence on climate change.
When has this increasing trend started?
The Intergovernmental Panel on Climate Change (IPCC) AR6 reports a speedier growth in the atmospheric concentration of methane over the period between 2014–2019. The IPCC’s 2019 Special Report on Climate Change and Land (SRCCL) reported a resumption of atmospheric methane concentration growth since 2007.
«There are still investigations for the actual cause of this increase. Atmospheric methane levels have been increasing since 2007, after the stabilization period between 1999 to 2006. It’s a topic of investigation, and unfortunately, there’s not much consensus in the scientific community on the major drivers for the post-2006 increases».
What generates atmospheric methane?
A plethora of different sources generates the methane found in the Earth’s atmosphere. There is fossil fuel production, biomass burning, waste management, and the decay of organic matter in wetlands. Animal agriculture is another source of methane, as this gas is a byproduct of digestion by ruminant animals like cows.
«Atmospheric methane comes from both natural sources like the natural wetlands and anthropogenic; man-made sources like ruminant livestock, waste and landfills, fossil fuel emissions, and biomass burning. Those are primary sources of it».
What has caused the record annual increase in atmospheric levels of methane in 2021?
Though determining the specific contribution of each methane source in the variations in annual increases of atmospheric methane is challenging; scientists have been able to assess the extent of the impact of the production and use of fossil fuel on the total methane emissions.
According to the IPCC AR6 Working Group III; global methane emissions from the energy supply accounted for about eighteen percent of the global GHG emissions from the energy supply. Thirty-two percent of global methane emissions, and six percent of global GHG emissions in 2019.
The challenge to separate natural and anthropogenic
«A lot of research recently is starting to converge to believe that the biological emissions sources are the dominant driver of the post-2006 increase; while the fossil fuel emission increases play a role, it is a smaller one, compared to the biological emission increases. The biological sources include the natural ones like the natural wetland and the anthropogenic part; which is the ruminant livestock, and waste and landfills. It remains a challenge to separate the contributions of natural behavior from the anthropogenic part». Explained Xin (Lindsay) Lan.
«The atmosphere levels in 2021, in particular, were an alarming signal. Because we see the highest annual increase in our system measurements starting from 1983. Something significant may have happened in 2021. Possibly 2020 as well, because in 2020, we also saw a record increase in atmospheric methane level. In 2020, and 2021, we are in the La Niña phase of the ENSO. During this weather pattern, we typically will see more rainfall over the tropical land regions where a lot of the wetlands are located. So these are good possibilities that we are seeing a pretty large increase from these tropical wetlands emissions in 2020 and 2021».
The calculation of methane levels
Each year NOAA’s Global Monitoring Laboratory collects more than 15,000 air samples. These samples come from monitoring stations located all around the world. They are then analyzed in a laboratory in Boulder, Colorado, United States.
Every year in spring, NOAA calculates the global average levels of the previous year of carbon dioxide, methane (CH₄), nitrous oxide (N₂O), and sulfur hexafluoride (SF6) which are the four primary greenhouse gases in the atmosphere.
These global averages are calculated through the use of air samples from sites from the Global Greenhouse Gas Reference Network and samples collected at another fifty cooperative sampling sites.
How to reduce methane levels
Because of this greenhouse gas’s shorter lifetime, methane reductions could be significant in particular in relation to near- and medium-term temperatures.
As assessed by the scientists behind the IPCC Working Group III report, “Climate Change 2022: Mitigation of climate change”; limiting global warming to around one-point-five degrees Celsius necessitates for global greenhouse gas emissions to peak before 2025 at the latest and cut by forty-three percent by 2030. At the same time, methane emissions would need a reduction by about a third.
According to the United Nations Environment Programme and Climate and Clean Air Coalition 2021 “Global Methane Assessment: Benefits and Costs of Mitigating Methane Emissions” report; achieving a pathway that allows global warming to stay within one-point-five degrees Celsius above pre-industrial levels; would necessitate a reversal of the ongoing rising trend in methane emissions; a profound reduction of anthropogenic methane emissions by 2030.
The need of policies
As stated in the aforementioned report, this could be accomplished through the implementation of policies. aimed at implementing targeted controls on specific sectors, policies to produce behavioral change, and policies to bring about vast cross-sectoral emissions reductions.
«Even though we do not know for sure what’s the major driver of the post 2007 atmospheric methane increase, we already know that the fossil fuel component is a very large part of the atmospheric methane emissions, as it’s responsible for about thirty percent of the global total methane emissions. That is primarily from leaks, as methane is used as a natural gas fuel: it’s a waste of energy. That seems to be a low-hanging fruit and the first step to reducing methane emissions. The increase in wetland emission of methane indicates climate feedback as a response to the long-term temperature increase; driven by the long-term emission of greenhouse gases. It’s crucial that we stop emitting more greenhouse gases in the atmosphere, particularly CO2 because CO2 has such a long-lasting impact on the atmosphere».
Xin (Lindsay) Lan
Research scientist at NOAA’s Global Monitoring Laboratory and University of Colorado Boulder.