Ocean surface temperature limit

Guest post

Richard Willoughby[1]


contact: scientist@bomwatch.com.au

Main points

  • Observations for at least the last 50 years of open ocean surface temperature provide clear evidence that the annual average ocean surface temperature is limited to 30 degrees Celsius with short-lived excursion up to 32 degrees Celsius.  This observation contradicts the predictions of climate models that show tropical ocean surface temperature perpetually rising.
  • The formation of clouds in response to the surface temperature of tropical oceans limits the surface insolation.  Once the surface temperature reaches 32C the cloud becomes sufficiently persistent that surface heat input and heat output reach a balance.  The consequence being that 32C is the maximum possible temperature of open ocean water. 
  • The ocean surface temperature limiting mechanism is tightly linked to the atmospheric water content.  Once the atmospheric water content reaches an equivalent depth of 45mm, a process of cyclic deep convection sets in whereby water vapour is literally catapulted as high as 12,000 metres into the atmosphere by convective instability.  This is a well-defined physical process detailed in the paper.
  • The paper challenges the concept of “Greenhouse Effect” where radiating gasses such as water vapour is assumed to only cause surface heating.  The key failure with climate models is the parameterising of clouds which are, in fact, formed from different phases of atmospheric water.  Once the atmospheric water reaches 45mm, the mode change to cyclic cloudburst results in the atmospheric water becoming a cooling agent rather than a warming agent at lower level.


The satellite era has provided abundant data with broad coverage of the global energy balance, atmospheric conditions and surface temperature.  Observation of the ocean surface temperature data from satellites provides compelling evidence that the ocean surface temperature rarely exceeds 30 degrees Celsius.  Rare exceptions like the Persian Gulf, which reaches up to 35 degrees Celsius, provides the key to identifying that cyclic cloudburst is a surface temperature limiting process.  Cloudburst is rare in the Persian Gulf and it is the only sub-tropical ocean surface exceeding 28 degrees Celsius that has not experienced a tropical cyclone in recorded history.

What we did

In addition to the satellite data, surface level data from the tropical ocean moored buoy arrays was evaluated to observe the surface temperature limiting process in operation through one hour intervals displaying the exquisite precision of this natural atmospheric-ocean system.  A series of charts within the paper demonstrates the same process across the three tropical oceans separated by thousands of kilometres and at different times of the year all regulating ocean surface temperature to a limit of 30 degrees Celsius.

A single column atmospheric model was developed through the course of this study to quantify convective instability and that led to the understanding that the increasing persistency of high level cloud reduced surface insolation by increasing cloud short wave reflection.  Clear sky conditions reduce rapidly with surface temperature above 28 degrees Celsius.

Detailed analysis, month-by-month of top of the atmosphere radiation balance and the level of atmospheric water unearthed a key parameter that the role of water vapour pivots about a level of 45mm.  Below that level, the water vapour is a warming agent through long-wave radiation absorption while above that level it is a cooling agent through the process of convective instability dominating cloud formation and increased cloud short-wave radiation reflection.

Principal findings

  • Current climate models assume the ocean surface temperature can continue to increase without constraint.  Clouds in climate models are parameterised and their formation is not tightly linked to surface temperature.  These fundament flaws mean climate models predict physically impossible outcomes.  They are not representative of Earth’s climate system.  The warming trend all climate models predict for the Nino34 region is clearly not evident in the actual recorded data over the last four decades.
  • Until climate models can replicate the physics of deep convection, tightly linked to surface temperature rather than the naive parameterisation of clouds, they will remain nothing more than extended weather models with useful predictive ability of a few days.
  • The behaviour of water in Earth’s atmosphere follows clearly defined processes that depend on the physical properties of water, in all phases, and atmospheric pressure.  The only way the open ocean surface temperature can exceed 32C is through a substantial increase in atmospheric pressure.  There is strong proxy evidence that higher ocean surface temperature were recorded in the Cretaceous period when the atmospheric pressure was approximately 10% higher than present time.  This is consistent with the temperature limiting process detailed in the paper.
  • Observations of the attributes of water in the atmosphere contradict the heat trapping assumption of atmospheric water described by the “Greenhouse Effect”.  Water in the atmosphere is not heat trapping but rather a temperature regulating component that increases radiating power (the sum of reflected short wave radiation and emitted long wave radiation) when the surface warms and reduces radiating power when the surface cools through reduced cloud cover enabling more surface insolation. 

The full report can be downloaded here .

[1] Professional Electric Engineer consulting in engineering risk for major projects with an enduring interest in natural catastrophes and changing climate.

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