The clogs of that which might overscar

The loftiest star of an unascended heaven,

Pinnacle DIM in the intense inane.

Percy Bysshe Shelly

Two ‘wrongs’ CAN make a ‘right.’

Origins unknown

Many years ago, when I first came to the desert and fell hopelessly in love with the vast open space of the American Southwest, I was always reminded, even then, that human technology and the advance of "civilization" lurked nearby. Or in my case, just overhead...about five miles to be exact. Transcontinental jet traffic, commercial and military, filled the skies. I used to marvel at the way the sound of their ram jet engines, moving at only 1100 feet per second, reached the ground and my vantage point, several moments after the jet had passed by me.

And for as long as I can remember, our beloved western skies have been marred by the ever-increasing grid of contrails that the big planes leave behind. Some days are worse than others, as air traffic fluctuates and as the humidity in the sky rises and falls. Some conspiracy people believe these are not contrails at all, but "chemtrails," high altitude mists of various poisonous concoctions, sprayed upon a un-witting civilian population by the government to make us all stupid and compliant (and here I thought Reality tv, Prosac and Paris Hilton were to blame). I’ll leave the chemtrail theories to Art Bell.

What I can confirm is that as these contrails criss and cross each other during the day and as high altitude winds disperse them, the narrowly defined streamers of exhaust and water vapor begin to merge with each other. By late afternoon, they often appear to have created their own weather. Sunny days give way to a high thin cloud cover and the sun doesn’t have the warmth to it that it had just a few hours earlier. On a global scale, shouldn’t this have a cooling effect everywhere?

But it makes no sense. We live in the Age of Global Warming. Wouldn’t this phenomenon have the opposite effect? Welcome to "Global Dimming."

I’m not making this up.


According to Wikipedia, "Global dimming is the gradual reduction in the amount of global direct irradiance at the Earth’s surface that was observed for several decades after the start of systematic measurements in 1950s. It is thought to have been caused by an increase in particulates such as black carbon in the atmosphere due to human action. The effect varied by location, but worldwide it was of the order of a 4% reduction over the three decades from 1960––1990."

In the mid-80s, a researcher from the Swiss Federal Institute of Technology stumbled upon a discovery that made no sense at all. Atsumu Ohmura had routinely checked sunlight levels at points across Europe, but to his surprise, his findings showed that levels of solar radiation had actually declined over the last several decades. Even 20 years ago, there was a growing consensus among scientists that the Earth was getting hotter, not cooler and the effects of global dimming could only cool things off. Surely Ohmura was mistaken or insane.

But by 2001, Ohmura’s findings were verified when Gerald Stanhilll and his colleague Shabatai Cohen, both from the Volcani center in Israel, proved that solar radiation had declined by .23% to .32% annually from 1958 to 1992.

So what the hell was going on here? Sunlight is not reaching the earth’s surface with the intensity that it once did, which should be chilling us down a bit, but instead the planet seems to be heating up. It’s almost too ironic to be believed.

"Global dimming" is caused by particulate pollution and aerosols. It can also be exacerbated by jet contrails. The idea that contrails were contributing to this phenomenon was dismissed by many scientists and there was little hope of proving it until September 11, 2001. When all commercial air traffic was grounded after the terrorist attacks in New York, Washington and Pennsylvania, scientists had a unique opportunity to measure the difference in ambient air temperatures. What they discovered was stunning—for the four day period that jets stayed on the tarmac, nighttime temperatures across North America rose by about 1 degree Celsius and daytime temperatures fell by about the same amount.

Black carbon and sulfates, the chief culprits in global dimming, are particularly noxious to humans and as a result, were some of the first forms of pollution to be dealt with by developing countries in Europe and North America. Pollution controls reduced the amount of particulates and aerosols in the atmosphere which may explain why the effects of ‘global warming’ are being more keenly observed in the first years of the 21st Century.

That’s guessed it. The pollution caused by global dimming actually decelerates the effects of global warming! But with our recent efforts to reduce sulfate pollution, the effects of global dimming have been diminished and the rate of global warming has increased. And some scientists have even suggested increasing the levels of particulate/aerosol pollution to combat global warming. The Russian scientist, Mikhail Budyko, a damn prophet by any stretch of the imagination, predicted more than 30 years ago that global warming would someday reach a crisis stage and proposed that burning massive amounts of sulfates in the stratosphere could engulf the atmosphere with a thin haze, sure to reflect the light and save the planet from itself.

He was unsure how to address the side effects of sulfate pollution like acid rain, cardio/pulmonary health problems, great variations in global rainfall and the short-term effects of aerosols (we’d have to keep burning them regularly to maintain the effect).

But isn’t it comforting to know that we, as humans, can make the world better, even as we screw it up? Or at least that we can convince ourselves to feel better. What else matters?

Jim Stiles