In 1926, Vladimir I. Vernadsky published The Biosphere, fundamentally reframing Earth as a dynamic planetary system shaped by the continuous transformation and migration of matter under the influence of life. He later introduced the concept of the noosphere to describe the stage at which human mind becomes a geological force capable of reorganizing biogeochemical processes. Written on the centenary of The Biosphere, this Perspective revisits and extends Vernadsky’s systemic logic in the context of contemporary climate science.

Climate is commonly framed as a radiative imbalance driven primarily by non-condensable greenhouse gases, with water vapour treated as fast thermodynamic feedback. While this framework robustly explains global energy balance, it underrepresents the structural role of water within the biosphere. We propose a complementary perspective: climate is an emergent property of biosphere organization, and water is the principal coupling mechanism between energy and matter across scales.

Water redistributes solar energy through phase change and latent heat flux, enables the biological conversion of electromagnetic energy into chemical energy via photosynthesis, and transports carbon and nutrients through soils, vegetation, rivers, and the atmosphere. At regional and watershed scales, soil moisture, evapotranspiration, and precipitation recycling regulate surface energy partitioning and hydroclimate variability. Human activities including land-use change, irrigation, groundwater extraction, dam construction, and urbanization alter this biosphere–water coupling, reshaping energy flows and biogeochemical fluxes beyond the effects of greenhouse gas emissions alone.

Recognizing climate as a function of biosphere integrity does not contradict existing assessment frameworks; it situates them within a broader thermodynamic and biogeochemical context. Integrating water governance and land-surface processes into climate policy reframes mitigation and adaptation as responsible participation within the biosphere, an operational expression of the noosphere in the twenty-first century.