Rapidly changing climatic patterns have profoundly affected the rainfall shifts and global average temperatures. With global warming, the glaciers and ice sheets are melting, and now this ice loss has been related to a direct impact on the global carbon cycle. According to a research team led by the University of Leeds, rapidly melting glaciers lead to an increase in carbon emissions, which in turn accelerates climate change.
For the first time, glacier-fed mountain rivers have been linked with higher rates of plant material decomposition, which is one of the main factors in carbon emissions. Published in the journal Nature Climate Change, these findings were supported by the Natural Environment Research Council.
Experts believe that this “unexpected climate feedback” indicates that global warming is resulting in glacier loss which is further rapidly breaking down the complex carbon molecules in the rivers. As global warming is speeding up glacier loss, the water channeled into the river streams is getting warmer and less prone to sediment movement and reduced water flow, providing a favorable condition for fungi to thrive.
Image: Pura Eventura
The fungi breeding in these rivers decompose the organic matter like leaves and break the complex carbon compounds that eventually get released into the atmosphere. This integral process of river carbon recycling has been observed in 57 rivers flowing from six mountain ranges across the world in the US, Austria, France, Norway, Ecuador, and New Zealand.
This is an unexpected form of climate feedback, whereby warming drives glacier loss, which in turn rapidly recycles carbon in rivers before it is returned to the atmosphere.
said Sarah Fell, the lead author of Leed’s School of Geography and water@leeds.
To measure this process, research teams used artists’ canvas fabric strips that replicate plant materials that accumulate in the rivers. As the canvas is made from cotton, mainly composed of cellulose, which is the world’s most bountiful organic polymer and is found in plant leaves that mount up water bodies naturally.
This fabric was left in the river for a month and then tested to determine its tensile strength. The strips ripped easily, indicating that the aquatic fungi have colonized them. This research concluded that carbon molecules are decomposing rapidly in the warmer rivers, as a result of reduced water flow from glaciers.
Co-author Professor Alex Dumbrell and his team at the University of Essex analyzed the fungi in the samples and reported,
Our work showed that measuring a specific gene that underpins the activity of the cellulose-degrading enzyme (Cellobiohydrolase I) meant we could predict cotton strip decomposition better than using information about the abundance of fungal species themselves, which is the more commonly used approach. This opens up new routes for research to improve our predictions about changes in carbon cycling.
Even though algal and plant growth is minimized in glacier-sourced rivers due to low water temperature, unstable river channels, and increased levels of sediments, the breakdown of organic matter is a significant fuel to these aquatic ecosystems.
In regions like Alaska and New Zealand, the glacier-fed rivers flow through the forests, extending the exposure to plant matter in the rivers. As the glacier loss accelerates, less water will flow into the river and they are less likely to change courses. Furthermore, it is predicted that more plants and trees can grow on the receding bankside, which would lead to more accumulated leaf litter in the river. These alterations could provide a perfect environment for fungal bloom, accelerating the processing of carbon in mountain rivers across the world.
The rapid ice loss not only threatens the water availability across many regions but also puts many coastal regions in danger of floods. In any case, melting glaciers and changing climate have threatened many lives; and if the global community keeps on failing to address the climate crisis, the planet is doomed.