New paper links warming since 1950 to ENSO and cloud cover variations

John McLean writes of a new paper about the pattern in global average temperature anomalies since 1950 and how they are linked to changes in cloud cover and ENSO:

global-temperature-vs-cloud-coverKey points of the paper:

  • Indicates that the temperature pattern can be attributed to a
    sequence of events, namely a shift in the prevailing ENSO conditions,
    then a reduction in total cloud cover and then a shift on cloud
    (decrease in low level cloud that was largely offset by an increase
    in mid and upper level cloud)
  • Uses the Trenberth, Fasulo & Kiehl energy balance diagram to show
    that the loss in total cloud cover caused an increase in heat energy
    being absorbed at the Earth’s surface that was greater than the
    increase that IPCC 5AR claims was due to greenhouse gases
  • Indicates that greenhouse gases played little if any part in the
    warming, which not only refutes the IPCC’s belief or opinion but also
    means that there is negligible, or even no, 16 or more years’ of
    “missing heat” to be found.
  • Shows the changes in cloud cover and temperature both as global
    averages and then for the six latitude bands each of 30 degrees, the
    latter indicating the changes in cloud cover applied to most latitude
    bands except the Antarctic and to a less extent 30S-60S.
  • Doesn’t attempt to identify the reason for the reduction in total
    cloud cover or the shift from low level cloud.

McLean writes:

On the last point above, I think a reduction in micro-particle emissions probably contributed.  The disappearance of London’s “pea soup” fogs after the ban on the burning of coal is probably a good precedent. It would be ironic if the reduction in micro-particle emissions was due to government legislation because that would mean that the warming was manmade.  To be fair though, it was probably the first deliberate attempt to clean up the atmosphere even if it didn’t come with a warning about possible changes to weather patterns.  We also shouldn’t forget that there may be other causes, such as changes to cooking fuel in the tropics.

The paper is available free of charge via

Late Twentieth-Century Warming and Variations in Cloud Cover

Author John McLean  Department of Physics, College of Science Technology and Engineering, James Cook University, Townsville, Australia.


From 1950 to 1987 a strong relationship existed between the El Nino-Southern Oscillation (ENSO) and HadCRUT4 global average temperature anomaly, interrupted occasionally by volcanic eruptions. After 1987 the relationship diverged, with temperature anomaly increasing more than expected, but was re-established after 1997 at an offset of ~0.48°C higher. The period of increased warming from 1987 to 1997 loosely coincided with the divergence of the global average temperature anomalies over land, which are derived from observation station recordings, and the global average anomalies in sea surface temperatures. Land-based temperatures averaged 0.04°C below sea temperatures for the period 1950 to 1987 but after 1997 averaged 0.41°C above sea temperatures. The increase in the global average temperature anomaly and the divergence of land and sea surface temperatures also coincided with two significant changes in global average cloud cover. Total cloud cover decreased during the period from 1987 to 1997 and, for most of the remainder of the period from 1984 to 2009, decreases in low-level cloud were accompanied by increases in middle and upper level cloud. These changes can be found in both global average cloud cover and in each of the six 30°C-latitude bands. The impact of these changes in cloud cover can account for the variations in HadCRUT4 global average temperature anomalies and the divergence between land and sea temperatures.