Carbon offset flip-flop?

Glenn Reynolds, a big supporter of carbon offsets and cap-and-trade strategies--NOT--writes today:
In an effort to ameliorate the effects of global warming, several groups are working on ventures to grow vast floating fields of plankton intended to absorb carbon dioxide from the atmosphere and carry it to the depths of the ocean. It is an idea, debated by experts for years, that still sounds like science fiction — and some scholars think that is where it belongs. . . .

The ship plans to dissolve tons of iron, an essential plankton nutrient, over a 10,000-square-kilometer patch. That’s equivalent to 2.47 million acres (3,861 square miles on land or 2,912 square nautical miles). When the trace iron prompts growth and reproduction of the tiny organism, scientists on the WeatherBird II plan to measure how much carbon dioxide the plankton ingests. The idea is similar to planting forests full of carbon-inhaling trees, but in desolate stretches of ocean. “This is organic gardening, not rocket science,” said Russ George, the chief executive of Planktos, the company behind the WeatherBird II project. “Can it possibly be as easy as we say it is? We’re about to find out.”
Like the dreaded Merkle Cloud, this could be dangerous if overdone. Don't plunge us into a new ice age, please. (And wouldn't that be a good plot for a thriller -- evil scientist, in cooperation with Hugh Chavez-like tropical dictator, deliberately triggers an ice age!) Just remember, you can never trust Plankton.
Evil Scientist. Cute. Unfortunately, the article does give voice to supporters of iron seeding who claim scientists "have an enormous vested interest in preserving this as a research topic alone. If this subject remains in academia for the next 10 or 20 years, it will certainly get a bunch of senior scientists on to retirement age, but it won’t do much for the planet." Thanks for that deep analysis.

What makes this ironic, though, is that it seems Instapundit tentatively supports iron seeding [given the part of the article he quotes]. Which would put him on the pro-carbon-offset side on this one:
In Europe, where there is a market for carbon credits, it is now worth only $2 to offset a ton of carbon emissions. But not long ago, that figure was $35, and it is expected to rise again as the limits imposed under the Kyoto Protocol on global warming start to bite. Planktos believes that it can make a healthy profit if it receives $5 a ton for capturing carbon dioxide.

“The cost of offsetting carbon through these technologies is less than the cost of building solar panels or windmills,” Mr. Kammen said. “There’s no question that this is going to grow,” he said of various carbon offset strategies.
Carbon offsets: bad if Al Gore participates, good if it's a techie geo-engineering-ish sci-fi fantasy.