The impact of glacier melting on downstream ecosystem

We are living in a warming world, and the 21st century is warming rapidly compared to preindustrial times, according to the IPCC. Glaciers are a vital component of the Earth system. They not only store water but also vast amounts of microbes, viruses, and nutrients. On the Tibetan Plateau alone, glaciers are estimated to contain around 1023 cells, 2000 Gg of dissolved organic carbon (DOC), and 500 Gg of nitrogen. As temperatures rise, these glaciers are melting at accelerated rates, especially over the past 40–50 years. When glaciers melt, water flows into downstream ecosystems—rivers, proglacial lakes, and foreland areas, and eventually into the sea. Along with water, bioavailable nutrients and microbes are released, which may benefit oligotrophic downstream ecosystems and arid lands. However, glacier meltwater can also release potentially harmful pathogens, posing a risk to human health. This raises an essential question: is glacier melt a benefit or a threat? To address this, we focus on two scientific questions: How does glacier melting impact downstream ecosystems? And, do microbes released from glaciers pose risks to downstream communities?