What role does freshwater play in climate mitigation? 3 questions to Nureen Faiza Anisha

In a series of five webinars, SIWI and fellow experts will explore how water can be used more effectively as a tool to mitigate climate change. Each webinar explores a different sector, with insights based on new research summarized in the landmark report The essential drop to reach net-zero: Unpacking freshwater’s role in climate mitigation.

On 16 March, the discussion will focus on freshwater systems. Report author Nureen Faiza Anisha from Oregon State University gives us a quick overview on the key role freshwater plays in climate mitigation.

Why is it critical to consider the freshwater systems in climate mitigation strategies?

When we talk about climate change mitigation through natural systems, we commonly talk about ocean, forests and soils, and their role is widely acknowledged in achieving net zero target. The role of freshwater ecosystems (such as wetlands, rivers, lakes, etc.) in achieving climate mitigation targets has not yet been widely acknowledged to the extent reflecting their potential. But these aquatic environments can act as both greenhouse gas (GHG) sources and sinks based on their environmental conditions and management practices. This duality to be both source and sink is what makes freshwater systems important in the global carbon budget.

For example, rivers globally are estimated to account for about 3% of global terrestrial N2O emissions and this rate of emission is increasing. On the other hand, river systems, particularly floodplains, can efficiently sequester carbon too.

Again, wetlands have one of the highest stores of soil carbon in the biosphere, storing more than 30% of the estimated global carbon emissions, despite covering about 7% of the world’s surface. But when drained or disturbed, we not just lose the stored carbon pool in the wetlands, we deplete our future carbon sinks. Hence, it is important to understand which conditions trigger emissions from freshwater systems and which ones enhance carbon sequestration. We can only utilize freshwater systems for climate change mitigation when our management decisions are well-informed.