Never has it been so pressing to address climate change. So let’s hurry to embrace a proven part of the solution. The radical (but not new) concept of agroforestry – be it integrating trees to create shade over coffee bushes, adding trees to Colombian cattle ranches, or managing and encouraging shea trees to flourish amid millet crops in the Sahel – must move to centre stage.
The Global Carbon Project estimates that 2017 will see a two per cent rise in worldwide carbon dioxide emissions, reversing the downward trend of the previous few years.
Almost a quarter of these emissions come from agriculture and the conversion of forests and wetlands into farmland.
This year is also set to be one of the hottest three ever recorded, according to the World Meteorological Organization. And, unlike 2016, 2017 has managed this even without a temperature-boosting El Niño weather system.
Flash floods in Southeast Asia, drought in East Africa, and melting glaciers in Latin America are just three examples of the extreme weather events linked to climate change that affect all corners of the world.
This is, truly, a global disaster, and one largely of our own making.
But we also have the power to mitigate global warming, through reducing emissions of CO2 and increasing its absorption by expanding or protecting “carbon sinks” such as forests.
One especially effective but still yet to be fully recognised mitigation strategy is agroforestry – the purposeful regeneration, planting, and maintenance of trees and woody bushes on farms and rangeland.
Already, almost a billion hectares of agricultural land across the world contains trees that farming families deliberately manage side by side with their crops and livestock. Around 1.2 billion people depend on these agroforestry systems.
The soil, vegetation, and biomass on every hectare of such land can capture 3.3 tonnes of carbon per year – much more than that captured by land without trees.
Recent research indicates that tree cover on agricultural land across the planet absorbs some 0.75 gigatonnes of carbon a year. That’s a sizable chunk of the 9.75 gigatonnes of CO2 the world emits annually.
As well as absorbing carbon, the trees and shrubs grown among crops and on pastureland deliver a range of lucrative benefits to farmers, such as timber, fuel, fruit, oil, nuts, and animal fodder.
Nitrogen-fixing trees also enrich soils by withdrawing the element, which is essential for plant growth, from the atmosphere. This can lessen the need for chemical nitrogen fertilisers, which have a powerful global warming effect, both as they are made and as they eke back into the atmosphere.
Finally, the presence of trees on agricultural land improves groundwater recharge and regulation of water, thereby increasing yields of crops, milk, and meat.
Agroforestry therefore not only mitigates global warming, but also helps farmers adapt to the often devastating effects of climate change, such as floods, droughts, and unpredictable rainfall patterns.
Without the additional sources of income trees can deliver, farmers whose crops are damaged or destroyed by such weather shocks are often forced to take steps that drive them further into poverty, such as selling tools and consuming seeds reserved for planting.
Research conducted in 2011 in western Kenya by the organisation I work for found that “agroforestry improves farm productivity, off-farm incomes, wealth, and the environmental conditions of… farms”, and that it releases farmers from “detrimental coping strategies”.
In the last year, as the Armageddon facing the Earth concentrated the minds of policymakers and activists, agroforestry has received some much welcome recognition and accolades.
Drawdown, a major international project based on field research by 200 scientists, features two forms of agroforestry in its list of 100 solutions to global warming that are already in use. The solutions are ranked by the extent to which they would reduce CO2 emissions by 2050 if they were adopted at realistic rates.
Silvopastoralism, where trees are combined with pasture, increasing carbon sequestration up to tenfold, comes in at number nine, ahead of nuclear power, wind turbines, and electric vehicles. Creating a canopy of tall trees over one or more layers of lower-lying crops (coffee and cacao are common examples) – a practice known as multistrata agroforestry – is listed in 28th place.
Governments of developing states are also turning to agroforestry with a lot of hope.More than 20, including agricultural giant India, cite agroforestry in their climate change action plans under the Paris Agreement.
Scientists have been aware of the benefits of agroforestry for decades and farmers for millennia, and the practice is gradually expanding every year. But with 22.2 million square kilometres of agricultural land on the planet, there’s a long way to go.
Donors and development banks need to wake up to the importance of trees in farming systems. Too many promote an agricultural vision of large treeless fields. While this may look modern, it is profoundly high-risk. Without trees, how will groundwater recharge? How will soil carbon be maintained? What will stop soil blowing away? Where will pollinators forage?
Agroforestry might not be a silver bullet, but it has a vital role in cushioning farmers from the harshness of weather patterns gone awry, and the world from the downward spiral of climate change.