Climate change threatens to alter methane emissions in the Amazon, study reveals

Sub: Env

Sec: Climate change

Context:

New research from the University of São Paulo highlights how climate change could disrupt greenhouse gas dynamics in the Amazon rainforest, with significant global consequences.
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.

Source: DTE