Geo-Engineering -- Is It Right (or Very Wrong) To Tweak Mother Nature?

The concept of geoengineering or Earth shading -- in which scientists deliberately manipulate the Earth's climate in order to counteract the changes in atmospheric chemistry and the overall effects of global warming -- is a very real consideration, one that was quite recently discussed at a National Academy of Sciences meeting.  Some might call it toying with the environment or our whole climate system on a planetary scale. Decades ago, scientists first determined that Mother Nature takes the lead on this front. Using the volcano model as an example, when they erupt, the particulates released into the air reflect sunlight which in turn generates a cooling effect. But...what if we were to create that effect without volcanoes?

Proponents of global temperature management might argue that it may become a technology out of necessity. With increasingly hotter temperatures across the planet, there will likely be extreme cases in the the near future (such as drought-induced famines or collapsing ice sheets) where we will have no choice but to interject. To turn a blind eye might result in catastrophic results, right? So, what are scientists proposing to do in order to achieve the desired effect?

• Make artificial trees designed to capture carbon dioxide from the air.
• Introduce sulfur dust into the stratosphere via commercial flights of 747s.
• Cover deserts with aluminum foil.
• Spray seawater particles into the air (in order to make clouds brighter).
• Seed the ocean with iron to stimulate the growth of plankton (which naturally metabolize carbon dioxide).
• Launch millions of mirrors into orbit.

These experiments, however, could create widescale disasters.

• We could inadvertently trigger a drought and famine while attempting to cool the planet.
• Particles in the stratosphere that block sunlight could also damage the ozone layer, which protects us from harsh ultraviolet light.
• Altering the stratosphere could reduce precipitation in Asia, where it waters the crops that feed 2 billion people.
• A large part of the ozone layer above the Arctic Ocean could be destroyed (with the atmospheric sulfur method).
• Iron seeding might produce even more CO2.
• A desert could begin to bloom while a major crop producing region could be rendered bone dry.

What are your thoughts on this scientific backup plan? Can you identify any positive aspects? Does it compromise ethics and morals?