Related Experiment Video
Updated: Oct 19, 2025
08:18
Design and Use of a Full Flow Sampling System FFS for the Quantification of Methane Emissions
Published on: June 12, 2016
16.9K
Atmospheric methane and nitrous oxide: challenges alongthe path to Net Zero
Euan G Nisbet1,2, Edward J Dlugokencky3, Rebecca E Fisher1
1Department of Earth Sciences, Royal Holloway, University of London, Egham TW20 0EX, UK.
Summary
The causes of rising methane (CH4) and nitrous oxide (N2O) emissions remain unclear, despite their significant impact on global warming. Urgent research is needed to understand sources, sinks, and mitigation strategies for these potent greenhouse gases.
Area of Science:
- Atmospheric chemistry and climate science.
- Greenhouse gas dynamics and climate change.
- Environmental monitoring and policy.
Background:
- Methane (CH4) emissions have shown a concerning rise since 2007, accelerating notably from 2014 and reaching record levels in 2020.
- This increase is accompanied by an isotopic shift towards values more depleted in 13C, indicating a potential change in emission sources.
- The rising CH4 trend deviates significantly from greenhouse gas scenarios designed to limit global heating to below 2°C, highlighting an urgent knowledge gap.
Purpose of the Study:
- To comprehensively understand the sources, sinks, trends, and inter-annual variations of methane (CH4).
- To improve the quantification of CH4 sources and sinks, including latitudinal and seasonal variations, to better understand the methane cycle and its anthropogenic component.
- To address the poorly understood dynamics of nitrous oxide (N2O) emissions and their contribution to climate change.
Main Methods:
- Independent verification of nationally declared emissions inventories (UNFCCC) using top-down observations.
- Quantification of indirect effects on natural emissions, such as changes in aquatic ecosystems.
- Assessment of emerging mitigation options for CH4 and N2O from various sectors.
Main Results:
- The precise causes for the renewed rise in methane (CH4) and its isotopic shift remain poorly understood.
- Nationally declared emissions inventories require independent verification through top-down observations.
- Options for mitigating both methane (CH4) and nitrous oxide (N2O) emissions are rapidly improving across multiple sectors.
Conclusions:
- Understanding methane (CH4) and nitrous oxide (N2O) dynamics is critical for effective climate change mitigation.
- Reductions in CH4 and N2O emissions represent some of the most attractive immediate options for climate action.
- Further research into emission sources, sinks, and indirect effects is essential for accurate climate modeling and policy development.
Related Concept Videos
01:20Overview of Nitrogen Metabolism
10.1K
Nitrogen is a very important element for life because it is a major constituent of proteins and nucleic acids. It is a macronutrient, and in nature, it is recycled from organic compounds and stored in the form of ammonia, ammonium ions, nitrate, nitrite, or nitrogen gas by many metabolic processes. Many of these metabolic processes are carried out only by prokaryotes.
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this...
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this...
10.1K
01:22Inorganic Nitrogen Assimilation
160
Nitrogen is an essential element in biological systems, forming a crucial component of proteins, nucleic acids, and other cellular constituents. Many bacteria and archaea acquire nitrogen in the form of nitrate (NO₃⁻) or ammonia (NH₃), which are then assimilated into biomolecules through specific enzymatic pathways.Assimilatory Nitrate ReductionWhen nitrate enters the cell, it undergoes a two-step reduction process known as assimilatory nitrate reduction. Initially, the enzyme...
160
01:15Metabolism of Chemolithotrophs
331
Chemolithotrophs are microorganisms that obtain energy by oxidizing inorganic molecules such as hydrogen gas (H₂), ammonia (NH₃), reduced sulfur compounds (H₂S, S²⁻), and ferrous iron (Fe²⁺). Unlike heterotrophic organisms that rely on organic carbon, chemolithotrophs transfer electrons from these inorganic donors to the electron transport chain (ETC), generating a proton motive force (PMF) that drives ATP synthesis through oxidative phosphorylation.
331
01:49The Nitrogen Cycle
56.3K
Nitrogen atoms, present in all proteins and DNA, are recycled between abiotic and biotic components of the ecosystem. However, the primary form of nitrogen on Earth is nitrogen gas, which cannot be used by most animals and plants. Thus, nitrogen gas must first be converted into a usable form by nitrogen-fixing bacteria before it can be cycled through other living organisms. The use of nitrogen-containing fertilizers and animal waste products in human agriculture has greatly influenced the...
56.3K
01:30Environmental Applications of Microorganisms
465
Microorganisms play a pivotal role in maintaining ecosystem balance by recycling essential elements such as carbon, nitrogen, and phosphorus, as well as supporting processes like bioremediation, wastewater treatment, and biofuel production.Microbes in Elemental CyclesIn the carbon cycle, microorganisms decompose organic matter, releasing carbon dioxide via aerobic respiration. This carbon dioxide is subsequently used by photosynthetic organisms to synthesize organic compounds, closing the...
465
01:28Carbon-dioxide Fixation
187
Carbon dioxide fixation in prokaryotes enables the assimilation of inorganic carbon into organic molecules, supporting biosynthetic pathways, sustaining ecosystems, and contributing to the global carbon cycle. It also has industrial applications in carbon capture and bioproduct synthesis. Autotrophic organisms rely on this process to utilize CO₂ as a carbon source in diverse environments.The Calvin CycleThe Calvin cycle is the most widespread carbon fixation mechanism, primarily used by...
187