Context: 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.  

• The study reveals contrasting changes in methane emissions and uptake in the Amazon’s floodplain and upland forest soils, driven by rising temperatures and increased flooding.

Key Findings

• Amazon’s Role in Methane Regulation: The Amazon plays a crucial role in global methane levels, acting as both a source and sink for this potent greenhouse gas.

• Floodplains and Upland Forests:

• Floodplains (covering 800,000 square kilometers during the rainy season) contribute up to 29% of global wetland methane emissions. In these waterlogged areas, methane-producing microbes thrive.

• Upland Forests, usually methane sinks, are highly vulnerable to changes in temperature and humidity. Methane uptake in upland forests dropped by 70% in warmer, drier conditions.

Research Method

• Soil samples from both floodplains and upland forests were exposed to temperatures of 27°C and 30°C, with varying humidity levels, over 30 days.

• Results showed that while methane emissions in floodplains remained stable, methane-producing microbes increased.

• In upland forests, the number of bacteria and archaea (organisms responsible for methane cycling) declined, showing their sensitivity to warming.

Methane Cycling and Microbial Activity

• Methanotrophic Microorganisms (those that consume methane) were active in both aerobic and anaerobic conditions in floodplains, showing adaptability to climate change.

• In contrast, upland forest microbes are less resilient, which could disrupt the balance of methane emissions in the Amazon.

Implications

• Global Impact: The Amazon’s shift in methane dynamics could significantly worsen global greenhouse gas concentrations, as the region’s role in both emitting and absorbing methane is crucial for global climate regulation.

• Climate Change Sensitivity: The Amazon’s upland forest ecosystems are particularly fragile, raising concerns about increased methane emissions as climate conditions change.

About Methane

• It is the primary component of natural gas, and is responsible for approximately a third of the warming we are experiencing today.

• Characteristics:

• It is a colorless odorless gas, flammable water insoluble gas.

• It is also known as marsh gas or methyl hydride.

• It is easily ignited. The vapours are lighter than air. Under prolonged exposure to fire or intense heat, the containers may rupture violently and rocket.

• It is a powerful and short-lived greenhouse gas, with a lifetime of about a decade and a Global Warming Potential about 80 times greater than that of carbon dioxide (CO2) during the 20 years after it is released into the atmosphere.

Where does methane come from?

• It sometimes comes from non-human sources like wetlands. These habitats contain things like permafrost, which is frozen ground that’s also filled with carbon from animals and plants that have been dead for hundreds of thousands of years.

• As temperatures rise with global warming, wetland permafrost thaws. That unleashes carbon, previously locked in the ice, in the form of CO2 and methane.

• Around 60% of the methane that makes it into the atmosphere comes from human activities.

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.