The Next Iron Age?

Geoengineering idea triggered controversy

In 1988, an oceanographer named John Martin stood up during a lecture at the Woods Hole Oceanographic Institution and in mad-scientist’s voice said, “Give me half a tanker of iron, and I’ll give you an ice age.”

“We all joked about it later,” said Jack DiTullio, a College of Charleston biochemist working with Martin at the time.

But Martin’s comments triggered a tidal wave of publicity. Critics dubbed Martin “Johnny Appleseed” and “Iron Man.”

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Martin was an out-of-the-box thinker. Early in his career, he was tasked with testing the long-term effects of radiation on phytoplankton in the Caribbean. At that time, the U.S. government was considering using nuclear weapons to widen the Panama Canal. The plan was abandoned but Martin was fascinated by the effects of traces of metals, such as zinc and iron, on phytoplankton.

He had long wondered, for instance, why some areas of the ocean had lots of phytoplankton while others did not. Over time, he developed a hypothesis: During the earth’s natural cooling or warming periods, land masses grew drier, prompting winds to whisk iron dust into the seas. This acted like a fertilizer, triggering massive phytoplankton blooms.

These blooms sent more oxygen into the air and more carbon dioxide to the ocean floor. With less carbon dioxide, the planet cools.

In 1988 when he made his remark at Woods Hole, he had no proof that traces of iron could trigger phytoplankton blooms, but he had a chance a year later on an expedition to Antarctica. DiTullio was aboard the Polar Duke as researchers collected samples and laced them with iron. Phytoplankton levels increased dramatically.

Martin made plans for a much larger experiment near the Galapagos but died in 1993, shortly before the expedition. But when scientists sprinkled iron across 25 square miles near the islands, they could smell the difference within a few days: Phytoplankton blooms filled the area with chlorophyll, consuming tons of carbon dioxide in the process.

“It turned out that he was right,” DiTullio said. “John Martin opened our eyes to the importance of trace metals in oceans.”

Since then, at least 10 other studies confirmed Martin’s hypothesis, effectively proving that human beings could transform the ocean into a massive beaker. Left hanging was the question whether people could geo-engineer the planet’s oceans and air without creating other catastrophes.