Albedo and Earthshine

Richard A. Lovett has an article in the June edition of Analog Magazine wherein he discusses various anomalies about the solar system. In particular, he reports on Philip Goode’s work at California’s Big Bear Observatory.

They realized that light reflected onto the moon was an excellent proxy for variation in the Earth’s albedo and have been measuring Earthshine for several decades. What they did discover is variation on an apparent decadal cycle. The variation is sufficient to match the magnitudes assigned to global warming. This all runs in the 2 to 4 watts per square meter range and of course, they have not been coincidal.

Obviously this is a factor able to make a difference as around thirty percent of incoming solar radiation is reflected back out. So what is the source of the variation? Again, it is obviously cloud cover that does vary and this is actually a good way to measure that variation.

One other factor enters the equation. Low clouds promote cooling and high clouds promote warming. Getting a headache yet?

The article speculates furiously on what all this may mean, but I suspect we are not much further ahead. While we have isolated variables that need to be measured, we are far from any conclusion except to warrant expanding the data collection.

That can be affected by the creation of a global chain of observatories measuring earthshine on the moon. If that can also be tied into satellite monitoring, then perhaps we can actually understand the impact of manmade aerosols. I suspect high resolution data will turn out to be illuminating. With Earthshine we have the other side of an albedo summation equation.

The point I want to make is that we have here an order of magnitude calculation for variation in the Earth’s albedo. This can be compared to solar radiation variation of 1.2 watts per square meter due to sunspots which exhibits a ten plus year cycle and has also been blamed for climate change. Variation of the albedo is easily twice that of the Sun itself.

This also begs another question. In a perfect world, increased warmth will produce more water vapor and therefore more clouds and therefore a higher albedo with a corresponding drop in absorbed sunlight. In any event, this all shows that net albedo is a much more important player than anyone thought.

Once again the CO2 conjecture remains buried in a medley of other active variables, sporting the same magnitudes and happily going whatever direction they seem to like.

We are however, uncovering apparent decadal cycles, like the sunspot cycle, the hurricane cycle, the drought cycle and the albedo cycle that all seem to be expressed in cloud variation and therefore local climatic variation.

This laid overtop a recovery from the little ice age that has been underway for two centuries and little except speculation that any of this is linked.

We can make three assertions: (1) In the long run the northern hemisphere left alone will warm to Bronze Age conditions.

(2) Eventually, an unknown event will cause the waters of the Atlantic to be chilled, precipitating a long period of cold conditions focused in Europe.

(3) Neither event has any likely relationship to these cyclic changes. We will let the jury stay out on the CO2 conjecture.

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