Sunscreen The Planet: A New Way To Fight Global Warming

In an idea inspired by the eruption of a volcano, ambitious scientists are proposing a novel approach to dealing with global warming: just apply sunscreen on the entire planet.

The project aims to use a number of high-altitude balloons to disperse millions of tons of titanium dioxide into the Earth's stratosphere. Titanium dioxide is a nontoxic chemical found in sunscreen, plants, and our food.

The titanium dioxide would be pumped skyward via flexible pipes and then hoisted into the unmanned balloons which would be flying 12 miles high. Using a "hypersonic" nozzle, the balloons would then spray a layer a millionth of a millimeter of up to three million tons of titanium dioxide into the stratosphere.

The effect this amount would have is astonishing. The layer, a millionth of a millimeter thick, would be enough to offset the temperature increase from a doubling of today's carbon dioxide emissions.

The plan is inspired by the 1991 eruption of Mount Pinatubo in the Philippines. The eruption released 20 million tons of sulfur dioxide into the atmosphere that ended up cooling the Earth's temperature by a quarter of a degree Fahrenheit for two years. In fact, a previous proposal suggested doing just that - filling the skies with sulfur.

Titanium dioxide, however, is seven times more effective at scattering light than sulfur, and comes without much of the environmental risks sulfur poses. Sulfuric acid can bring on droughts, because it not only scatters sunlight, it also absorbs it, and it tends to degrade the ozone layer.

Project leader and chemical enginner Peter Davidson is assured of the minimal risk in coating our planet in titanium dioxide.

"No evidence has been found for health hazards that I am aware of, and at these minute concentrations, issues are most unlikely."

By choosing to use a balloon-dispersal system, the project will cost less than earlier ideas of using aircrafts or rockets.

"The biggest expense is getting the chemical up into the stratosphere," says Rob Jackson, an environmental scientist.

Both scientists agree that the system will, and cannot, be implemented for years to come. It's important to further study the possible effects, and to justify the $3 to $4 billion bill it would cost the United States per year.

 "Anytime we've injected chemicals into the atmosphere, we've been surprised by the chemistry that results," says Jackson.