Disruption in Emissions and Uptake of Methane | 16 Oct 2024

Source: DTE 

Why in News?

Recently, new research warned that climate change could disrupt the Methane Cycle (methane emissions and uptake) in the Amazon rainforest, leading to significant global consequences. 

• The methane cycle refers to the series of processes that control the production, consumption, and release of methane (CH4) in the environment.  

What are the Key Highlights of the Research on Methane? 

• Floodplain Ecosystems: Floodplains (waterlogged areas) in the Amazon contribute up to 29% of global wetland methane emissions. Climate changes increase the risk of methane-producing microbes. 
• Upland Forests: Upland forests in the Amazon function as methane sinks.  
  • The study found that methane uptake in upland forest soils dropped by 70% under warmer, drier conditions, signalling a reduction in their capacity to mitigate methane emissions. 
• Methane Cycling: The research also delved into the role of methanotrophic microorganisms, which consume methane.  
  • Isotope analysis showed that both aerobic and anaerobic methane-consuming microbes were active in floodplains, highlighting the complex interactions in methane cycling in the Amazon. 

What is a Methane Cycle? 

• There are many sources like wetlands that release methane (CH4) into the atmosphere. There are also sinks or ways that methane is trapped or destroyed.  
• The methane cycle begins in the soil where methane gas is created by microbes.  
• Soil methane is consumed by methanotrophs, microorganisms that feed on methane.  
• Methanogens make more methane that methanotrophs consume.  
  • Methanotrophs live in drier oxygen-rich upper layers of soil because they need oxygen to function.   
  • Their food bubbles rise to the surface, releasing methane into the atmosphere.  
  • This methane joins methane from other sources, such as landfills, livestock and exploitation of fossil fuels. 
• The main mechanism for removal of methane from the earth’s atmosphere is oxidation within the troposphere by the hydroxyl radical (OH). 
  • Hydroxyl radicals are a form of sink because they scrub the atmosphere clean of pollutant molecules and break them down. For this reason OH is known as the ‘cleanser of the atmosphere’. 
  • After reacting with OH, atmospheric methane is converted to CO2 by a long series of chemical reactions. 
• Some of the methane present in the troposphere passes into the stratosphere where a similar process removes it from the atmosphere.. 

How Global Warming Can Impact Methane Cycle? 

• Imbalance in Sources and Sinks: In an ideal world, methane sources would be balanced with methane sinks, as with CO2, however, global atmospheric methane concentrations are rising as a result of human activities.  
  • Scientists are worried because as the planet warms, even more methane will be released from soils or other places adding to the global warming problem. 
• Methane Clathrates: Methane crystals form in cold, oxygen-poor undersea sediments. Clathrates are also trapped in permafrost, the permanently frozen soil in the arctic and subarctic latitudes.  
  • Clathrate ice, also called methane hydrate, is solid and white, similar to water ice. However, this ice consists of water molecules that are frozen around molecules of methane. 
• Role of Clathrate Deposits: Clathrate deposits were once sinks where methane was isolated.  
  • However, as the planet warms, some of these deep, cold sediments are melting, sending methane bubbling to the surface.  
  • Because CH4 is a greenhouse gas, it traps heat in the atmosphere and warms the planet more. 

How Disruption in the Methane Cycle Can Have Global Consequences? 

• Contributor to Global Warming: Methane is the second most significant greenhouse gas driving climate change, following carbon dioxide (CO₂).  
  • Due to its high global warming potential (28 times greater than carbon dioxide over a 100-year period), even small amounts of methane can significantly contribute to global warming. 
• Halts Checking Global Warming Efforts: According to data from the United States National Oceanic and Atmospheric Administration, even as carbon dioxide emissions decelerated during the Covid-19 lockdowns of 2020, atmospheric methane shot up. 
• Health Impacts: Methane is a key precursor gas of the harmful air pollutant, tropospheric ozone.  
  • Ozone is responsible for about 1 million premature respiratory deaths globally.  
  • Globally, increased methane emissions are responsible for half of the observed rise in tropospheric ozone levels. 
• Effects on Air Quality: Increased methane emissions deplete hydroxyl radicals (OH), which act as a natural detergent for atmospheric pollutants. This reduction allows other air pollutants to persist longer, worsening air quality. 
• Agriculture Impacts: Methane contributes to staple crop losses of up to 15% annually by increasing atmospheric temperatures and producing tropospheric ozone. 
• Economic Impacts: Methane’s impacts on climate change and public health contributes to a yearly loss of roughly 400 million hours of work globally due to extreme heat. 
• Biodiversity Threats: Methane-induced climate change disrupts ecosystems, causing shifts in species distributions, loss of biodiversity, and destabilisation of ecological interactions, impacting plant and animal health. 

How Can We Balance the Methane Cycle? 

• Enhanced Landfill Design: Lining systems and gas collection wells in landfills can be used to capture methane for energy use rather than allowing it to escape into the atmosphere. 
• Livestock Management: Additives such as seaweed or specific enzymes have been shown to lower methane emissions from ruminants which can help mitigate emissions from livestock. 
• Aerobic Treatment Methods: Technologies such as aerobic digestion can effectively eliminate organic matter from wastewater without producing methane. 
• Rice Cultivation Practices: Implementing alternative wetting and drying practices in rice cultivation can minimise methane emissions by reducing the time fields are flooded.  
• Soil Health Management: Enhancing soil health through the use of organic fertilisers and crop rotation can reduce methane emissions by promoting aerobic conditions in the soil, which are less conducive to methane production. 
• Pest Management: Research into environmentally friendly pest management strategies could help regulate termite populations in areas where their emissions are significant. 
• Coastal Ecosystem Restoration: Protecting and restoring coastal ecosystems, such as mangroves and salt marshes, can enhance their ability to absorb carbon and mitigate methane emissions from sediments. 
• Safe Extraction Practices: If methane hydrates are to be extracted for energy, developing safe extraction technologies that minimise methane leakage is crucial. 
• Reducing Fossil Fuel Use: Transitioning to renewable energy sources can reduce overall methane emissions associated with fossil fuel extraction and consumption.