Dimming the Sun and Climate Change

I watched a movie called "Dimming the Sun." It was produced by NOVA and was on a national public television station.

The long and the short of it was that in certain parts of the world the sun is not as bright as it used to be. I'll briefly describe the interlocking themes. As they say it will just be the top level of what was presented and discussed. Don't hold me to getting it exactly right but what I will describe is the gist of it.

Theme #1: About 30 years ago a scientist was asked to look at the ground temperature and the amount of light hitting the ground in Israel. He painstakingly kept records from multiple sensors over a period of time. This data revealed about what they had expected but now they had actual scientific data to support their hunches. It was important because they were going to use his findings to make informed decisions on how much water was going to be needed for national irrigations projects.

Several years ago and for some reason or other the same scientist went back to take the measurements again, I presume to see if there was any interval difference, or whatever. He was stunned to discover that the amount of light impacting on the ground had decreased. He was amazed. (ok, ok, I know the details that you want aren't here, but you can rent the movie and see it in its entirety and then add your comments to this entry.)

Naturally he wrote up his findings and published it in a scientific journal. He was surprised to find out that it drew virtually no response or interest. In the movie or on the basis of my own interpretation, I think that happened because it flew against the grain of the growing body of data on global warming. In science that's not surprising for two essential reasons. First because when ideas become popular, even with scientists, there is a ground swell which eventually becomes somewhat established dogma and this can lead people to disregard information which doesn't fit that pattern. Secondly, if you do enough research it appears that you will find some information which is different just from a statistical probability point of view. There I go again, and I was trying to keep it simple.

Theme #2: Then there was a climatologist in Germany who did a similar study in Germany or that part of Europe. She had no knowledge of the first bit of research above. She was similarly greatly surprised to find similar trends and she also published it. Once again there was little interest

Theme #3: Then there were two climatologists in Australia who were interested in studying rates of water evaporation on the surface of the earth in their area. I think they also had interval data which showed that the amount of "pan evaporation" had gone down since the time of their first measurements years previously. (They called it "the pan" because they filled a pan with a measured amount of water and then later measured how much water had to be added to the pan to bring it up the original level.)

I don't recall this part but I think they were saying that they were perplexed by the "apparent anomaly" because the temperature at the surface had increased and therefore they would expect that the pan rate would be greater also. They went to publish their paper describing this and quite "by chance" they came across the publications from Themes 1 and 2. They then ran some more experiments and found that the "pan rate" was determined by temperature, wind and the light intensity of the sun on the ground. They expected that the wind and temperature would be more important but they discovered that the light intensity was in fact the most important factor influencing the "pan rate."

Theme #4: The above themes plus a few others were then combined with some studies which looked at the influence of the amount of pollution / debris in the atmosphere on global warming in different parts of the globe. This multiyear study took place off the coast of India in a sprawling area of small islands collectively called the Maldeves. This area was chosen because on one end of the Maldeves the cloud cover was heavily influenced by the pollution coming out of China and India. On the other end of the island chain there was relatively little pollution in the cloud cover.

When the data was finally collected and analyzed it was found that the amount of light under the "polluted" clouds was less than the other area. This also had the effect of lowering the temperature in the areas of higher contamination. The explanation offered was that the particulates combine with water droplets in the atmosphere (clouds) and then the droplet-particles act as tiny mirrors which reflect the light back out towards the sun / space, with the net effect of "dimming the sun." (Please don't ask me why the particles don't reflect light off each other and then to my lay persons interpretation they would have a net effect of zero, i.e., an equal amount would be bounced or reflected equally in every direction.)

There was one other experiment which looked at the above theme in context of the influence of particulates and water vapor coming from the contrails of aircraft on light levels and surface temperatures. That was equally fascinating and was able to be conducted sadly because of the events of 9/11 where all air traffic was prohibited for a few days till things got sorted out. I'll leave that story for you to hear when you watch the movie.

The implications of this are important on a number of levels. What I understood was that the movie and the scientists were saying that pollution lowers the amount of sunlight impacting on the earth and by virtue of that lowers the temperature greatest in areas of greatest pollution. So does this mean that global warming is not happening? No, it means that the effect of dimming the sun is to lower the temperature in those areas of greatest pollution. Now here's the catch 22: pollution has to be lowered because of the significant impact on the health of those people who live in the areas of greater pollution. But in doing that the further effect will be that temperature will increase even more rapidly in those areas. Ironic isn't it that as the United States does a good job of decreasing the overall pollution of the atmosphere over the continental states, that the downside of that will (may) be a disproportionate increase in temperature. There were also other discussions in the movie of the impact of decreased evaporation at the surface of the earth on climate. How all this will impact on farming is of importance and perhaps some can comment on this.

This is a long post but I think it further points out how the climate of the globe is an integrated whole; what influences one part influences other parts. One moral of the story is that any one little piece of pollution may not have all that much impact, but the sum total is enormous. These researchers deserve a gold star for their tenacity.

In my next entry I will give you some of my thoughts about "dimming the sun" and Seasonal Affective Disorder.