Global dimming – an effect that few know exist and yet may be critical in understanding our rapidly changing climate. It all started back in the 1950s when a British scientist by the name of Gerry Stanhill was measuring solar energy in Israel as part of a study involving irrigation of crops. At the time he thought nothing of it until decades later when he discovered an astonishing 22% drop in sunlight globally using the data at the time. He began searching global meteorological records and found decreases globally ranging from 5-30 %. He published a report on the phenomenon in 2001 but it was largely ignored by the mainstream science authorities. Researchers in the Netherlands and other parts of the world have also come to accept the idea of dimming.
The whole idea doesn’t seem to fit with the global warming theory though…. or does it? There is another piece of evidence which seems to support the theory. This comes from something called the pan evaporation rate. For about 100 years now around the world agricultural scientists have been measuring how much water evaporates from a pan during the day. Each morning they refill the pan and record how much it took to get it back to the base level. From the 60s to the 90s there was a general decrease in the pan evaporation rate. While there are other factors such as humidity that affect pan evaporation the dominant one is the solar energy hitting the water.
So what is causing global dimming? Satellites show that the energy from the sun is relatively constant despite increased activity . The answer of course is pollution. The explosion of automobiles and industry has ejected incredible amounts of particulates into our atmosphere producing what we call smog and haze over most major cities. This then blows around the earth spreading like fog until it gets washed into the water cycle. Of course the haze is always being replenished by our ongoing economies. It begs the question how much can the earth really absorb? How much abuse can our planet take before it turns on us? Our planet has shown itself to be incredibly resilient but for how much longer?
Another factor in the equation is aircraft contrails. After Sept. 11th 2001, almost the entire fleet of US planes were grounded. Scientists seized the opportunity to take climate measurements in order to discern possible effects. During the three day grounding , a difference of 1 degree Celsius was noted which may not sound like much but in meteorological terms it was big.
The global dimming effect could mean that mainstream science has underestimated the effects of global warming and the greenhouse effect. This could mean catastrophic changes much sooner than anticipated. Now that governments have begun cleaning the air by enforcing tougher pollution standards, the dimming effect is starting to fade which leaves global warming free to do it’s worst.
The wiki page on global dimming has a lot more info for those interested in this aspect of climate science.