Lasers Another Tool in the Climate Engineer’s Box of Tricks?

More and more evidence mounts that the effects of global climate change are already drastically altering the ecology of our planet. The apparent acceleration of warming trends produces a call to action in many scientific and political circles, but the traditional chorus baying for enhanced efforts at conservation may never be capable of offsetting the momentum inherent in this change. This slowly dawning realization begins to push the once fringe science of climate engineering into the forefront of the public conversation. As part of this shift, terms like cloud seeding, once connoted with Soviet-era mad scientists shooting unpleasant sounding chemicals into the atmosphere, are not uncommon parlance in the mainstream outlets of daytime television and nightly news media. Modernizing the discussion even further, optical physicists at the University of Geneva discovered that firing short pulses of laser beams into the air may result in the desired effect of cloud seeding, rain, without the ecological uncertainty involved in aerosolizing the atmosphere with silver iodide, as was the preferred convention in times past.

Rain forms as water vapor condenses around tiny particulate debris in the air through a process called nucleation, beading up and becoming a drop of rain whose growing mass pulls it to the surface of the earth. Traditional cloud seeding methods involve scattering this debris (usually silver iodide) into the air onto which the water vapor can condense. Laser seeding, however, works by ionizing the oxygen and nitrogen atoms that are near the beam. These atoms are far more effective as nucleation agents when ionized than in their normal states. Following several short bursts from the Teramobile laser, researchers recorded as many as twenty times the number of water droplets in the laser’s path than they did before its firing. Of course, this creates only a tiny corridor of condensation, hardly the stuff of rainstorms.

The team in Switzerland is looking at ways of consistently producing the same effect when sweeping the laser(s) through the sky. If they are successful, they stand a remote chance at swaying a threatening sky into a rainstorm, but it will be quite a while before anyone is terraforming desert into savanna by laser light. Still, this innovation, in as much as climate engineering can be, is an ecologically responsible and relatively cheap alternative to past methods. As the data rolls in year after year confirming the rise of temperatures around the globe, climate engineering seems more probable an alternative than the immediate and drastic increase in conservation efforts necessary to potentially stall the current temperature trajectory. Discovering new techniques like this one that decrease the risk of tinkering with Earth’s hyper-chaotic weather system are necessary and encouraging next steps in that direction.

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~ by Wil Finley on May 2, 2010.

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