In 2012, an environmental entrepreneur named Russ George dumped a hundred tons of iron dust into the ocean a few hundred miles west of Old Massett, a coastal British Columbia fishing village.

The project, backed by the village, aimed to fertilize the ocean. George, inspired by a theory published by oceanographer John Martin in 1990, predicted that the iron would trigger an algae bloom. The algae would provide food for fish and reverse a years-long decline in the salmon population.

As a bonus, uneaten algae would ingest carbon dioxide from the atmosphere, die, and sink to the ocean floor, taking the carbon with them.

Algae did bloom. So did outrage among environmental groups and government agencies. Initial news reports suggested that George had violated international law. The Canadian government seized the data he had been collecting about the project.

George's story, told this month by Vox and in 2014 (with an update last year) by Pacific Standard, illustrates a major fear among those fighting climate change: that a go-it-alone country, corporation, or individual could take well-meaning unilateral action that makes things worse instead of better.

George has worked in a number of fields, including cold fusion energy, reforestation, and the carbon credit market. He has professed a mantra of "save the world, make a little money on the side."

He and his detractors are still arguing over his iron fertilization project. He considers it a rousing success. He's convinced that it sequestered a significant amount of atmospheric carbon at the bottom of the sea. He can't prove it because his data got seized.

As for the fish, there the data seem clear. According to the Alaska Department of Fish and Game, the following year saw a record harvest of Pacific pink salmon.

George's opponents say iron fertilization could create oceanic dead zones, red tides, and toxic fish. Indeed, Old Massett did experience red tides—dense blooms of toxic phytoplankton that deplete oxygen in seawater. Canada's Department of Fisheries and Oceans declared local shellfish unsafe to eat.

Environmental groups doubt George's claims of carbon sequestration and say the salmon boom can't be definitely linked to the iron fertilization. More generally, they find such freelance climate engineering projects terrifying.

Scientific papers have explored the sometimes scary ramifications of governments sponsoring ocean iron fertilization, individuals releasing heat-reflecting particles in weather balloons, and other renegade actors carrying out unregulated climate geoengineering.

History provides many, many examples of human attempts to improve the environment that failed spectacularly. Early in the 20th century, for example, South Florida developers looked at the Everglades, a broad, shallow river that covers much of the state south of Lake Okeechobee, and saw only useless swamp. They planted water-hungry melaleuca trees to try to dry up the muck. One nurseryman even flew over the Everglades in an airplane, sprinkling melaleuca seeds.

Melaleucas, native to Australia and Malaysia, have spread across more than 400,000 acres, mostly in South Florida. They suck up water, grow so densely that they displace native plants and animals, and constitute a serious fire hazard because their oily leaves burn so hot.

Meanwhile, we have learned that the Everglades encompasses a vibrant system of interconnected ecosystems that supports an incredibly diverse array of plants, birds, and animals—and also affects the quality of life in the urban areas that have grown along its fringes. Efforts have begun to restore the Glades.

That's why those in the environmental mainstream urge caution and international regulation. UCLA environmental law professor Ted Parson told Vox that George's project, which took place in international waters, and others like it "exist in a near legal vacuum."

What if one country wants to try a geoengineering project and a neighboring country strenuously objects, fearing adverse consequences? Faced with what it considered a major threat to its way of life and finding no legal mechanisms for protecting its interests, the complaining nation might resort to war.

The controversy and outrage that erupted after his iron-seeding experiment have left George embittered. "It worked like a charm," George insisted to Vox. "We put 100 tons of rock dust into 10,000 square kilometers. And that area of ocean swirled and mixed, and the ocean bloomed immediately. Fish arrived by the tens of thousands, whales arrived by the hundreds."

He said he hoped to continue his environmental work, arguing that he's part of the climate change solution, not the problem. "The greatest threat to the environment," he said, "is waiting for someone else to save it."