Chilling lesson from the past

chillinglesson

When hearing about the “global warming creates cold weather”-ad hoc explanation for our cold winter/spring, it all seemed familiar to me. I definitely heard that before. In the 1970s this was also how the coming Ice Age was explained. For example, this is how Science News brought it in 1975:

The principal weather change likely to accompany the cooling trend is increased variability-alternating extremes of temperature and precipitation in any given area-which would almost certainly lower average crop yields. The cause of this increased variability can best be seen by examining upper atmosphere wind patterns that accompany cooler climate. During warm periods a “zonal circulation” predominates, in which the prevailing westerly winds of the temperate zones are swept over long distances by a few powerful high and low pressure centers. The result is a more evenly distributed pattern of weather, varying relatively little from month to month or season to season. During cooler climatic periods, however, the high-altitude winds are broken up into irregular cells by weaker and more plentiful pressure centers, causing formation of a “meridional circulation” pattern. These small, weak cells may stagnate over vast areas for many months, bringing unseasonably cold weather on one side and unseasonably warm weather on the other. Droughts and floods become more frequent and may alternate season to season, as they did last year in India. Thus, while the hemisphere as a whole is cooler, individual areas may alternately break temperature and precipitation records at both extremes.

Indeed, very familiar when comparing what is proposed now as the reason for the current cold weather. Just somewhat different word preference. Read “Jet stream” for “upper atmosphere wind patterns”, “positive phase” for “warm periods”, “negative phase” for “cooler periods”, “Blocking” for “Stagnate”.

What were/are the effects:

  • Increased variability: check.
  • Alternating extremes of temperature and precipitation. Broken up into irregular cells. Check.
  • May stagnate over vast areas for many months, Check.
  • Unseasonably cold weather on one side and unseasonably warm weather on the other, Check.
  • Droughts and floods become more frequent. Check.

These effects are not unusual for a negative phase of the Arctic Oscillation. The Arctic Oscillation was predominantly positive for the 1980s and 1990s, which had an influence on the winters in the Northern Hemisphere. One time or another it was bound to go negative again. So how can one differentiate clearly between the two when the explanation has the same effect as the natural variation? Not to mention the scientists were surprised and had to again rebuild their theory to match the new observations.

The name of the phenomenon “Arctic Oscillation” is not used because at that time the phenomenon didn’t have a name yet. It was given by Wallace and Thompson at the end of the 1990s, who seem to consider it a natural process. In the current explanations of the warm cold, the name is not stated either, probably for other reasons.

This is how they showed it graphically in 1975:

chillingpossibilities_thmb
Source: Science News: Climate Change – Chilling possibilities

Compare it with current graphics:

fig17_9_thmb
Source: http://www.ees.rochester.edu/fehnlab/ees215/

So the same process seemed to be used to explain two opposites. In the 1970s to explain it was colder and we might go towards a new ice age. Now to explain global warming is still here and hey, it is getting colder because of “global” warming.

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