If global warming is essentially a problem of excess carbon dioxide, why just sit back and let it happen? Ambitious engineers have devised these "visionary" (some would say "crack-pot") engineering solutions.

Dumpin' iron
In 1990, aware that a shortage of iron was limiting the growth of free-floating plants called phytoplankton in the Southern Ocean, the late oceanographer John Martin advocated dumping iron powder into the ocean. He thought this would fertilize the plankton and remove millions of tons of carbon dioxide from the ocean water. Since this carbon dioxide originates in the atmosphere, he figured this would reduce atmospheric levels as well.

A 1996 test showed that 1000 pounds of iron fertilized the growth of 4 million pounds of plants, an impressive number. But even Kenneth Coale of the Moss Landing Laboratory, a co-leader of the 1996 experiment, doesn't advocate dumping iron into the ocean to solve global warming. In fact, he called that process "deplorable, environmentally irresponsible and logistically unfeasible." Go figure.

First satellite TV, now satellite PV?
If solar energy is kinda limited on earth -- what with those pesky nights and clouds -- it's super-abundant in space. In 1968, a scientist proposed placing giant satellites in high orbits. Vast photovoltaic (PV) cells on the satellites would generate electricity, which would be beamed by microwave radiation to Earth.

The latest version of that vision features smaller satellites orbiting closer to earth, which would keep the microwaves closer together, making them easier to capture. Scientists say the technology should be safe, since the chosen microwave frequency does not affect the human body. But you can bet your last peso it will be costly -- and controversial.

Low deposit, no return
If 2 billion metric tons of human-made carbon dioxide (out of a global output of about 7 billion tons) eventually winds up in the ocean each year anyway, why not just pump the stuff into the ocean to begin with? This intriguing engineering fix for global warming is actually getting serious consideration, despite the fact that separating carbon dioxide from smokestacks could consume as much as 30 percent of a power plant's electric output.

In 1996, a Norwegian oil company began depositing 1 million tons of carbon dioxide per year into a salt aquifer in the North Sea. More recently, the United States, Norway and Japan agreed to a $4-million test of a deep-sea dumpster off the coast of Hawaii in the summer of 2000. (Skeptics may ask why it's off Hawaii, and not, say Elizabeth, NJ, but realists answer that the ocean floor slopes steeply off Hawaii's Kona Coast, allowing easy access to the deep waters. It's got nothing to do with the surf. Nothing at all...)

To begin answering the many ecological and technological questions, the researchers will pump 300 tons into the water over the course of 30 days, and watch the results. See "Coming to Grips..." in the bibliography.

Come to think of it, our bibliography has plenty more on no-carbon energy.