The Importance of Forests for the Planet and Humanity

Abstract Forests are foundational to Earth’s life-support systems and human well-being. ScienceDirect-indexed research demonstrates that forests regulate climate through carbon storage and sequestration, cool land surfaces via water–energy cycling, sustain biodiversity that underpins ecosystem functioning, secure freshwater services through hydrological regulation, reduce disaster risks, and contribute directly to livelihoods, food systems, and public health. Forest loss and degradation—through land-use conversion, fragmentation, and unsustainable extraction—erode these services, intensify climate change, threaten biodiversity, and increase risks to human health including zoonotic spillover pathways. This narrative review synthesizes ScienceDirect literature across six interconnected roles of forests: (1) climate regulation and the carbon cycle, (2) biodiversity and ecosystem multifunctionality, (3) water cycling and hydrological services, (4) human well-being and health co-benefits, (5) socio-economic values and ecosystem service valuation, and (6) restoration and policy directions for sustaining forest contributions. Evidence highlights that forest–water–energy interactions are essential for carbon storage and climate cooling, that biodiversity supports stability and multiple ecosystem functions, and that forest ecosystem services have substantial economic value. We conclude with priorities for protecting and restoring forests: integrated land–water governance, safeguarding old-growth and connected landscapes, scaling restoration with hydrological realism, and ensuring equitable benefit-sharing and local stewardship. Keywords: forests; climate regulation; carbon sequestration; biodiversity; ecosystem services; hydrology; human health; restoration; deforestation; sustainability.