You read it on the Cat. My friend Ivan Kennedy, a Sydney-based Agricultural scientist with special interests in physics has applied some basic principles to explore the drivers of global warming and cooling. The model suggests two contrasting roles for carbon dioxide – enabling warming as a logarithmic function of concentration but also cooling as a linear function of concentration. Another prediction is a direct warming role for increasing evaporation of water above land in mid-latitudes due to a increased irrigation (evapotranspiration) and greening of vegetation.

Summary. A new hypothesis for explaining variations in climate based on Clausius’ virial theorem predicts that increasing use of water to grow food and fibre could have caused most recent global warming. The virial-action theorem provides a more convenient way than the current paradigm, adiabatic convection, to model variation in global temperature. The theorem’s equations suggest that about 4×10(power12) tonnes of irrigation water applied annually worldwide may be elevating and cooling the top of the atmosphere sufficiently to reduce outgoing longwave radiation (OLR) to space, warming the lower atmosphere. A similar mechanism would explain the warming effects of the El Nino-Southern Oscillation (ENSO) periodically affecting Australia’s climate. It is not so much a question of whether the temperature of the atmosphere varies – it does so continuously as its heat content changes: the real question is why, by how much and how serious is the risk to the global ecosystem?

For nerds, the long form of the story.