Cooling forest rainbow water vital contributor to farmer livelihoods

By Meine van Noordwijk, chief science advisor at the World Agroforestry Centre (ICRAF), based in Indonesia and professor in agroforestry at Wageningen University in the Netherlands.

Forests are widely recognized as critical to essential ecosystem services like clean water and air, but some of their greatest benefits are invisible to the human eye and have not been picked up in policy discussions.

Forests interact with the climate over long periods of time, as they store carbon — a greenhouse gas that contributes to climate change — in their trunks, branches, leaves and roots, which they use to grow.

They also build up soil carbon stocks. This makes healthy, standing forests invaluable in global efforts to prevent rising global temperatures through greenhouse gas emissions.

Forests, however, interact with climate more directly, as they use water to cool themselves and their surroundings, releasing moisture into the atmosphere — what we call “rainbow water.”

In an important but understudied aspect of the world’s water cycle, this invisible moisture comes back as rainfall nearby and very far from forests, depending on the location on the globe.

A new report released last week that I co-authored seeks to elevate our understanding of this phenomenon.

When forests are cut down, they release carbon into the atmosphere. And, just as detrimental, rainbow water dries up.

Depending on where the forests are, this can lead to major water shortages for those living “down wind” from where forest loss takes place.

One of the hotspots for this phenomenon is the Blue Nile Basin in Africa. When deforestation in the Congo reduces atmospheric recycling, people living all along the river — as far away as Egypt — are impacted.

Without rainfall, farmers lose their incomes; in some cases, they become refugees.

There are other hotspots worldwide. In Asia, deforestation in Myanmar impacts China. In Borneo, deforestation is leading to less rainfall, as the typically low wind speeds keep the recycling focused on local effects.

Fortunately, the solution to this problem is relatively simple. Protecting standing forests and allowing farmers to manage trees in their farms can replenish rainbow water, leading to predictable rainfall once again.

But even more needs to be done. Forest nations and the international community who are gathered this week to discuss progress on the U.N. Sustainable Development Goals must address the twin benefits of forests for climate–carbon storage and rainfall regulation—in plans for tackling climate change.

Careful management of the forests we do have can lead to better carbon storage and higher water quantity and quality.

It’s possible to reverse the vicious cycle of deforestation and water crises. But we need to act now.

Read the report by clicking here.

More about the author:

Meine van Noordwijk has for the past 25 years worked at the World Agroforestry Centre (ICRAF), based in Indonesia, lately as Chief Science Advisor. He also serves as Professor in Agroforestry at Wageningen University in the Netherlands. Born in the Netherlands he was trained as a biologist/ecologist and worked as researcher  on roots (plant-soil interactions), agroforestry as land use option in tropical forest margins, environmental consequences of land use change (including hydrology), and institutional responses to such, including payments for ecosystem services and ecocertification schemes. He developed simulation models that range from the scales of roots to the understanding of farmer’s land use decisions and its environmental consequences. A publication record is available by clicking here.