In the treetops: Understanding the planet’s ‘rainbow water’
Scientists study blue water, the surface resources available to people from our lakes, rivers and aquifers. They study green water, which is held in our plants and soils. Now a team of researchers is calling attention to the importance of “rainbow water,” the often invisible atmospheric moisture that plays a critical role in the connections between climate, forests, water and people.
What they’re looking at is how the destruction of forests in the Congo Basin or West Africa, for example, affects people who rely on water from the Nile River – because that water originates as atmospheric water from hundreds of kilometers away. Similar patterns exist in China, where water resources are linked to Southeast Asian forests, or in Argentina where they’re tied to the Amazon.
The recently released “Forest and Water on a Changing Planet” is a global assessment of the role of forests in providing and protecting water downstream but also downwind. It is the product of more than 50 scientists from 20 different countries, all contributing to a more holistic view of forests and water resources, and forging policy links among the relevant United Nations Sustainable Development Goals.
“It’s rediscovering the cycle, rediscovering the atmospheric connection between what happens on one piece of land and what happens elsewhere,” says Meine van Noordwijk, an agroforestry professor at Wageningen University in the Netherlands and chief science adviser to the International Union of Forest Research Organizations (IUFRO) based in Austria.
Van Noordwijk is lead author and co-editor of the IUFRO report with Irena Creed, the executive director of the School of Environment and Sustainability at the University of Saskatchewan in Canada. Creed, during a press conference on the findings, explained that the research demonstrates the need to think about forests in a different way.
“Many of us are aware of forests being about carbon. But forests are not just about carbon,” she said, referring to the role of trees in carbon sequestration. “They’re also about water and we need to bring that conversation into the international policy discussion.”
It’s important as climate change makes access to water resources more unpredictable, whether nations are developed or not. Van Noordwijk points to estimates that some 4 billion people are water-vulnerable in some capacity now, but there’s not an integrated approach to understanding the impacts, or developing and executing meaningful policy based on that integration.
India and nations across Africa, with their projected population growth, are at high risk for water crises that are integrated with food security, energy and economic impact. But so is Canada, where just one flooding incident can cause a $1 billion insurance fiasco. “The role of forests can help mitigate some of that extremes in the water, whether it’s too much or too little, by being a sponge for some of the water but also helping to regulate some of the flows downstream,” says Creed.
The IUFRO report also adds insight into the dynamics of atmospheric “rainbow water” in scenarios where there’s competition for land use – and not just in the developing world. One example noted in the report is Australia’s Murray Darling basin, which accounts for 14 percent of Australia’s overall land mass and where efforts to protect water drawdowns met with resistance from farmers dependent on irrigation.
