Could changing the color of the sky to counter global warming backfire?
March 25, 2009
The concept of delaying global warming by adding particles into the upper atmosphere to cool the climate could unintentionally reduce peak electricity generated by large solar power plants by as much as one-fifth, according to a new study by the National Oceanic and Atmospheric Administration (NOAA).
Global warming is one of the most important long-term issues that we have to deal with as a world today. We have pumped excess carbon dioxide into the atmosphere, which serves as an insulating blanket of air causing the world to trap more heat from the sun, and therefore increases the temperature globally. Our main approach to combating the warming of the earth is to reduce the amount of carbon we pump into the air in an attempt to keep atmospheric levels of carbon in control. However, some scientists feel that this reactive solution does not adequately combat climate change and the increasingly dire predictions emerging about the speed of its impact.
The last resort solution
One radical solution as proposed by scientists like Australia's Tim Flannery has proposed a radical alternative as a last resort solution: pump materials such as sulphur into the upper atmosphere in an attempt to block out a portion of the sun's rays, forming a giant human created blanket over the ozone layer. This would prevent the full amount of solar heat entering our atmosphere in the first place, and in turn lower the amount of carbon dioxide being trapped. One of the side-effects of this method would be that the sky would change color, taking on a deep purple hue, rather than the familiar sky blue that we know and love today.
The advantages of this approach is that it would allow us, as a race, to continue our technological expansion. It would lessen the urgency to cut back on our carbon emissions on which our society has evolved to depend.
There have been naturally occurring instances of such high atmospheric seeding. In 1991 Mt. Pinatubo erupted, spewing 20 million tons of sulfur dioxide into the atmosphere. This left a sulfuric acid haze over the world, which caused global temperatures to drop by about 0.9 degrees F (0.5C).
The problem with the last resort solution
However, such a strategy is not without its share of disadvantages. Daniel Murphy, a scientist from the National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory, has been researching one of the possible implications of such a geo-engineering project. While such atmospheric modifications would only be expected to deflect about 3 percent of the sunlight incident on the earth, Murphy has found that solar energy collectors would face a reduction of up to one-fifth of the usable energy that they collect presently. Even though 97 percent of the sun's light will make it through the Earth's modified stratosphere, much of it will be scattered, making the light diffuse. Diffuse light cannot be focused in the same manner that direct light can be, which lessens its usability in most optical systems. Almost all projects that harness solar energy require a large portion direct sunlight that can be focused and concentrated on a cell of some kind.
"The sensitivity of concentrating solar systems to stratospheric particles may seem surprising,” said Murphy. “But because these systems use only direct sunlight, increasing stratospheric particles has a disproportionately large effect on them.”
Murphy compared these predictions to output data from Solar Electric Generating Stations. After the 1991 eruption and found they lined up perfectly, supporting his prediction that there would be a 20% loss in usable solar power.
Locally and internationally solar energy is both viable and popular. As one of the most promising sources of alternative energy it is expected to play a large part in decreasing our reliance on fossil fuels. If we compromise the usefulness of this energy source in order to cool the atmosphere, we may end up using more fossil fuels which would result in pumping more carbon into the atmosphere to compensate for the lack of solar power. This may end with us leaving graffiti on the sky and not improving our situation with global warming.