Validating a physics-based back-of-the-envelope climate model with state-of-the-art data
An old conceptual physics-based back-of-the-envelope model for greenhouse effect is revisited and validated against state-of-the-art reanalyses. Untraditional diagnostics show a physically consistent picture, for which the state of earth's climate is constrained by well-known physical principles, such as energy balance, flow and, conservation. Greenhouse gas concentrations affect the atmospheric optical depth for infrared radiation, and increased opacity implies higher altitude from which earth's equivalent bulk heat loss takes place without being re-absorbed. Such increase is seen in the reanalyses. There has also been a reduction in the correlation between the spatial structure of outgoing long-wave radiation and surface temperature, consistent with increasingly more processes interfering with the upwelling infrared light before it reaches the top of the atmosphere. State-of-the-art reanalyses further imply increases in the overturning in the troposphere, consistent with a constant and continuous vertical energy flow. The associateion between these aspects can be interpreted as an entanglement between greenhouse effect and the hydrological cycle, where reduced energy transfer associated with increased opacity is compensated by tropospheric overturning activity.