For decades, a dominant argument for protecting forests has focused on carbon. Trees absorb carbon dioxide, store it in wood and soils, and slow the accumulation of greenhouse gases. A new scientific review argues this emphasis overlooks other ways forests shape climate and human well-being. Forests are not only a mitigation tool for the future climate. They also help people adapt to climate change now, shaping temperature, water and living conditions in ways felt close to where people live.
The paper synthesizes research on forests’ physical climate effects. At local scales, trees act as thermal buffers: canopies block sunlight and drive evapotranspiration, which converts heat into water vapor. Across dozens of field sites, daytime temperatures inside forests averaged about 4°C lower than in nearby open areas, while nights were slightly warmer. Extremes narrow—cooler afternoons, milder nights.
Cooling strengthens in hotter places. Tropical forests can exceed 6°C of relief relative to cleared land, and even urban trees reduce air temperatures on sunny days. During heat waves, apparent temperatures inside forests have been measured dramatically lower than outside, a difference that can shape whether outdoor work or daily activity is tolerable.
Deforestation therefore changes more than scenery. A recent study estimated that forest loss across the tropics has exposed hundreds of millions to higher temperatures and contributes to tens of thousands of heat-related deaths each year. In many places, the local warming from clearing land rivals the impact of global climate change over the same period.
Forests also reshape water systems:
Intercept rainfall and reduce flood risk in humid regions
Increase infiltration and groundwater recharge
Recycle moisture back into the atmosphere, influencing rainfall
Context is crucial. Forests deliver the greatest climate benefits where they naturally occur. Planting trees in ecosystems that evolved without dense canopy can produce unintended effects, including warming where dark foliage absorbs more sunlight than snow or grasslands. Even so, most regions capable of supporting substantial natural tree cover would experience net cooling once carbon storage and other factors are considered.
Large-scale processes add further complexity. Forests influence cloud formation, atmospheric chemistry and long-distance moisture transport. Evidence from places such as Borneo shows that heavy forest loss can raise daily temperatures, intensify heat extremes and reduce rainfall, while more intact landscapes remain comparatively stable.
Taken together, the findings recast forests as climate infrastructure. They moderate heat, manage water and shape local weather in ways engineered systems struggle to replicate. They cannot halt global warming on their own, but they can make a hotter world more livable.
A longer version of this piece was originally published at Forests don’t just store carbon. They keep people alive, scientists say