Rainfall: a new way to look at trees for climate mitigation

A side event at the UN climate change conference now underway in Paris (COP21) urged a new, easier-to-understand way to discuss trees and climate change mitigation: Rainfall.

'Alone', a photo by Yudha Lesmana, was finalist in the XIV World Forestry Congress photo competition. http://bit.ly/1OjlqSp

‘Alone’, a photo by Yudha Lesmana, was finalist in the XIV World Forestry Congress photo competition. http://bit.ly/1OjlqSp

Rainfall made through evapotranspiration from plant matter cools the air around, since plants use heat energy to release water into the atmosphere.  And a tree is more cooling than short vegetation; it uses 100–200 mm more water per year.

But the story is much more interesting, thanks to air currents that transport moisture from one place to another.

“Trees in one region of the world can have far-reaching effects in neighbouring, or even distant ‘teleconnected’ regions,” Dr Meine van Noordwijk, chief scientist at World Agroforestry Centre (ICRAF), said at the event, held in the Rio Pavilion section of COP21.

“Trees growing in East Africa and the Congo basin, for instance, support rainfall in Ethiopia, thus feeding the Nile, the longest river in the world and a lifeline for 11 African countries,” he added.

Join the launch of a new policy brief: Managing Forests for Water and for Climate Cooling on Sunday, 6th December at the Global Landscape Forum, Palais de Congres de Paris. Thematic Pavilion E, Achieving Sustainable Development Goals, Booth 29, 9-10am.

Forests and trees not only depend on precipitation for their survival, they also help to generate it. Around 40% of rainfall over land comes from vegetation on land, through evapotranspiration and transportation (the other 60% derives from oceans).

As such, trees represent an “ecological rainfall infrastructure.”

“As new evidence on the mechanisms of forest and tree effects on rainfall emerges, communicating the need to plant trees for rainfall should be stepped up,” said van Noordwijk. “And these trees will help mitigate climate change.”

Unlike carbon, we can see and feel rainfall, so the interest in planting trees for rainfall might be greater.

With the right trees, an ‘ecological rainfall infrastructure’ will serve to attenuate greenhouse gas emissions responsible for climate change, besides bringing myriad livelihood benefits to people. These include products as well as ecological services such as improved groundwater recharge and moderated flooding.

Download presentation by Meine van Noordwijk on Ecological Rainfall Infrastructure

Download new policy brief [PDF]: Ecological rainfall infrastructure: investment in trees for sustainable development. ASB Policy Brief 47. Nairobi. ASB Partnership for the Tropical Forest Margins. 6 p.

See photos from ICRAF participation at COP 21

Join the launch of a new policy brief: Managing Forests for Water and for Climate Cooling on Sunday, 6th December at the Global Landscape Forum. Thematic Pavilion E, Achieving Sustainable Development Goals, Booth 29, 9-10am.

Panel includes David Ellison (Consultant, Swedish University of Agricultural Sciences), Cindy Morris (INRA, France), Victoria Gutierrez (WeForest, UK), and Meine van Noordwijk (ICRAF, Indonesia)

Come join the discussion on why forests matter for water and climate cooling; How can we move from evidence to action?

About the session:

Ecological Rainfall Infrastructure: investment in trees for sustainable development

Rio Pavilion, COP21 Paris, France

Date and time: 02 Dec 2015, 14:00 to 15:30, as part of the Land Day of UNCCD.

Session organizers:

Dr. Meine van Noordwijk, World Agroforestry Centre. Email: m.vannoordwijk@cgiar.org


In many parts of the world local people are convinced that forests, trees and rainfall are related in more than one way: forests and trees not only depend on rainfall but help to generate it. Scientists confronted with this perspective have always denied such effects, or at best been ‘agnostic’, as it seemed impossible in their data to find evidence. New evidence on credible mechanisms for forest and tree effects on rainfall is, however, emerging. It can revolutionize current climate negotiations that all focus on greenhouse gas emissions. Biological rainfall generation may be as important for the water cycle as biological nitrogen fixation is for the nitrogen cycle. Managing trees for their roles in rainfall is easier to understand than the complex carbon story, and will offer new ways of reducing negative effects of climate change.



Introduction by the host (ICRAF) – Dr. Peter Minang, Global coordinator ASB Consortium for Tropical Forest Margins, World Agroforestry Centre

Opening remarks by Dr Dennis Garrity, Drylands Ambassador UN Convention to Combat Desertification

  • Keynote 1: Ecological Rainfall Infrastructure: investment in trees for for sustainable development – Dr Meine van Noordwijk
  • Keynote 2: Why forests matter for water, energy and climate: what we think we know – Dr David Ellison and a WeForest science synthesis team

Panel discussion with lightning talks

  • Launch of ASB-Policy Brief Policy on the topic and its relation to climate change negotiations (Dr Peter Minang, global ASB coordinator)
  • Seeing the forests as well as the trees (Dr Daniel Murdiyarso, CIFOR)
  • A meso-american perspective (Dr Eduardo Somariba, CATIE) Steps to close critical knowledge gaps (Dr Ravi Prabhu, DDG Research ICRAF)

General discussion

Closing remarks by the facilitator



Daisy Ouya

Daisy Ouya is a science writer and communications specialist with the World Agroforestry Centre (ICRAF). Over the past 15 years she has been packaging and disseminating scientific knowledge in the fields of entomology, agriculture, health, HIV/AIDS research, and marine science. Daisy is a Board-certified Editor in the Life Sciences (bels.org) and has a Masters’ degree in chemistry from the University of Connecticut, USA. Her BSc is from the University of Nairobi in her native Kenya. She has worked as a journal editor, science writer, publisher, and communications strategist with various organizations. She joined ICRAF in July 2012. Twitter: @daisyouya

You may also like...