An improved global understanding of river temperature could provide an important barometer for climate change and other human activities.

River temperature is the fundamental water quality measure that regulates physical, chemical and biological processes in flowing waters and, in turn, impacts ecosystems, human health, and industrial, domestic and recreational uses by people.

In a comment piece in the new journal, Nature Water, researchers led by the University of Birmingham, UK, and Indiana University, U.S., have called for an increased focus on both river temperatures and the factors driving temperature increases.

In particular, the researchers argue, we need a better understanding of the role played by humans on river water temperature.

A comprehensive bank of knowledge will lead to improved understanding of temperature changes on biodiversity, ecosystem functioning, and risks, including early warning of algal blooms, waterborne pathogens and effects on fish populations. These aspects may be critical for human survival in many areas of the globe.

Crucial to this understanding will be to rethink how we monitor and model river temperatures to improve our diagnosis of critical changes. In turn, this will play an important part in our ability to manage, mitigate and adapt to high temperature extremes that are damaging to aquatic organisms and ecosystem services for people.

"More attention has been given to other water quality indicators, such as nutrients and contaminants," explained co-lead author, Professor David Hannah, UNESCO Chair in Water Sciences at the University of Birmingham. "However, river temperature influences many of these factors. Emerging evidence shows that river temperatures are rising in response to climate change in many regions worldwide. On top of this human activity is altering water temperature further; but we still need to better understand this phenomenon and its implications."

Professor Darren Ficklin, co-lead author of Indiana University, added: "The knowledge we currently have is inconsistent, with large variations in scale and detail—and primarily taking place in richer countries. This severely limits our ability to sustainably manage river systems, protect ecosystems and balance the competing interests of stakeholders."

The researchers suggest a first step would be to create more complete and accessible river temperature archive, which draws all available data together, to highlight information gaps and underpin models for places and times (for example, into the future) for which we lack data. By co-producing river temperature knowledge in this way, the researchers also hope to promote collaborative research and management efforts with local and indigenous communities, avoiding 'top-down' decision-making on which types of data are most valuable