Purpose <p>This study numerically investigates the thermal interaction among the hydrosphere and atmosphere and its implications for climate change, under the simplifying assumptions of uniform flow and negligible evaporation at the interface.</p> Methods <p>A two-phase mathematical model in spherical coordinates is formulated, where the hydrosphere and atmospheric regions are coupled through trans-boundary conditions arising from temperature gradients. The governing non-dimensional equations are transformed into algebraic form using a finite-difference scheme and solved with Gaussian elimination, ensuring numerical stability and convergence. A comprehensive parametric analysis is conducted to investigate the influence of numerous parameters on the velocity and temperature distributions.</p> Results <p>Results reveal that stronger buoyancy forces at higher Grashof numbers intensify convective flow while reducing thermal gradients, whereas variations in viscosity, density, and conductivity substantially alter the efficiency of heat transfer.</p> Conclusion <p>These findings demonstrate that hydrosphere–atmosphere coupling significantly influences energy transport processes that are closely linked to climate dynamics. In particular, enhanced convection is associated with increased atmospheric instability, stronger weather systems, and feedback mechanisms that may exacerbate global warming. The study highlights the importance of capturing hydrosphere–atmosphere interactions as a foundation for advancing climate modeling.</p>