Water, Energy and Climate
Solar energy is the fundamental driver of the Earth’s climate system, while infrared emission is the system coolant. Net heating in equatorial regions and net cooling in polar regions drive both atmospheric and oceanic circulations. It is water, however, in all its three phases that provides much of the complexity and variability in the Earth system, as well as being the fundamental determinant of habitability for most of the biota. Energy and water are inextricably intertwined in the climate system on spatial scales from the molecular to planetary and on timescales from the instantaneous to millennia. External forcing of climate, whether by solar variability or changes in atmospheric composition or volcanic eruptions, alters the energy and the water cycle, as well as the complex relationships between them. These alterations provide feedbacks in the climate system that both amplify and dampen aspects of the original change. It is these feedbacks and their coupling to the non-linear dynamics of the ocean-atmosphere system that are the most challenging issue in understanding climate and predicting the magnitude of climate change in this century. Consequently there is an urgent need to increase understanding of these complex processes and their interactions in climate system and improve their representation in climate models.