At last year’s United Nations climate summit in Glasgow, more than 100 heads of state committed to halt and reverse forest loss by 2030. If successful, this pledge would play a huge role in fighting the climate crisis: forests can deliver an estimated one-third of annual mitigation needed to keep global warming to 1.5 degrees Celsius, the target set at the pivotal Paris meetings in 2015.
But forests are even more powerful than we previously thought.
As climate policymakers follow up on Glasgow’s developments when they gather at the U.N.’s COP27 negotiations in Sharm el-Sheikh, Egypt, this week and next to assess progress toward the Paris Agreement goals, new research adds compelling reasons why it is increasingly critical for leaders to double down on fulfilling their pledge.
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Deforestation historically has taken place to clear land for crops, livestock grazing or building development. In other cases, it’s the result of poor practices to harvest lumber
and wood pulp, and in some forests, to harvest palm oil.
Ending deforestation is already recognized as a double win for the climate. Healthy forests not only keep climate-warming carbon safely stored in trunks, branches, leaves, roots and soils; forests also actively pull carbon out of the atmosphere, providing a safe, proven and cost-effective strategy for mitigating the vast amount of carbon released every year from all sources, from transportation to agriculture.
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Now, a growing body of research is showing that forests have a whole set of additional, undervalued and overwhelmingly positive benefits for the climate. Through their impacts on the movement of moisture and heat into and through the atmosphere, forests improve food and water security, protect human health, and enhance our ability to adapt to a warming planet — and also supercharge tropical forests’ already significant global cooling benefits.
“ Through their impacts on the movement of moisture and heat into and through the atmosphere, forests improve food and water security, protect human health, and enhance our ability to adapt to a warming planet.”
As detailed in the report Not Just Carbon, non-carbon effects of forests on the climate merit urgent attention from climate policymakers.
Forests release moisture into the air, while the rough surfaces of forest canopies create wind turbulence, carrying heat and water into higher layers of the atmosphere. Trees also release particles such as pollen and aromatic compounds that help generate cloud cover, which in turn reflects the sun’s energy back into space. The net effect of these factors and carbon storage together at tropical and temperate latitudes is climate cooling, for both the local area and the planet.
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In fact, scientists estimate that the global cooling effects of tropical forests are as much as 50% greater than the effects measured by carbon alone.
Forests also regulate regional and local climate stability, sustaining climates in which food can grow and water is plentiful. They affect rainfall patterns up to hundreds of miles downwind, contributing to agriculture and municipal water supplies. For example, cities such as Buenos Aires, Argentina, Rio de Janeiro, Brazil, and Kinshasa, in the Republic of the Congo, depend on precipitation recycled by upwind forests for more than 45% of their water.
Healthy forests make for more climate-resilient local communities, while deforestation has a local warming effect that compounds global warming resulting from the greenhouse effect. Forest loss is already elevating average and extreme local temperatures, in what might be called a “rural heat island effect” that occurs when shade and evapotranspiration are removed, withering nearby crops
and exposing agricultural workers to heat stress, especially in the tropics.
“ Buenos Aires, Argentina, Rio de Janeiro, Brazil, and Kinshasa, in the Republic of the Congo, depend on precipitation recycled by upwind forests for more than 45% of their water. ”
And when local officials understand the more local benefits of protecting forests, they have both the motivation and authority to take action rather than feeling helpless to affect the trajectory of global climate change.
By failing to take forests’ biophysical effects on the climate into account, current policies systematically undervalue forests’ true value. These policies fail to anticipate all the climate risks associated with deforestation, and lead to responsibilities and resources being inequitably allocated within and between nations.
The good news is, there is ample room for policymakers to act through current agreements and institutions.
For example, although the Paris Agreement explicitly calls out the non-carbon benefits of forests, current ways of accounting for national climate action are denominated solely in greenhouse gas emissions.
Countries should consider adjusting their accounting to rectify the systematic bias against many forest-rich developing countries and Indigenous territories, which deserve more recognition and finance for the additional global cooling effects of protecting their forests.
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Global and regional institutions — including development financiers such as the World Bank — should step up their support to countries to assess and manage the risks of deforestation-related water and heat stress, and to cooperate to address the effects that cross national boundaries.
Further, all countries’ climate change adaptation plans should incorporate the local climate-stabilizing effects of forest cover on temperature and rainfall.
Wealthy countries have both a moral responsibility and self-interest to increase forest finance to developing countries for both climate mitigation and increased resilience.
“ Wealthy countries have both a moral responsibility and self-interest to increase forest finance to developing countries for both climate mitigation and increased resilience. ”
Forests are a dynamic and integral part of local and global climate systems — not just sticks of carbon. Failure to account for the entire scope of forests’ interactions with the atmosphere blinds us to the many ways that deforestation puts people and the planet at risk.
Both at and beyond the U.N. climate summit, policymakers would be wise to recognize forests’ immense power to fight climate change and to build healthy, food-secure, and resilient communities around the world.
Frances Seymour is a distinguished senior fellow with the World Resources Institute’s Global Forest Program.
Michael Wolosin is managing director of the NCS Roadmap at Conservation International’s Moore Center for Science.