Oct 8 - McClatchy-Tribune Regional News - Steve Jordon Omaha World-Herald, Neb.

A 2004 Science magazine article by two Princeton University scientists is just now attracting widespread attention in the global warming field.

Stephen Pacala and Robert Socolow maintained that proven technology can halt the increase in carbon dioxide if applied on a large scale over the next 50 years.

The authors divide into seven wedges a chart showing the projected increase in carbon dioxide, with each "wedge" representing 1 billion tons of increased annual carbon emissions. Pacala and Socolow suggest 15 options for cutting emissions and say there are other possibilities as well.

The article, cited in the October issue of National Geographic magazine, said delays will increase the number of "wedges" needed to prevent carbon dioxide from building up in the atmosphere.

At the same time, it said, researchers must immediately increase their work to develop revolutionary technologies that would reduce carbon production in the second half of this century.

Among the wedge-reducing options for the coming 50 years:

--Double the average mileage of 2 billion cars (about four times as many as today) from 30 miles per gallon to 60 miles per gallon, or reduce their average driving distance from 10,000 miles to 5,000 miles per year. Urban planning and telecommuting can help.

--Replace petroleum fuels with 34 million barrels of ethanol per day, about 50 times current production and requiring one-sixth of the world's cropland. Using carbon-based fuel to produce ethanol would reduce this option's impact.

--Use efficient heating, cooling, lighting and refrigeration in residential and commercial buildings. About half of these savings are in developing countries.

--Substitute natural gas for coal to generate electricity, capturing and storing carbon dioxide emissions and other fuel substitutions.

--Double the number of nuclear power plants, which would require restoring public confidence in safety and waste disposal and international security agreements on uranium enrichment and plutonium recycling.

--Install 4 million electricity-generating windmills, 100 times the current number.

--To absorb more carbon dioxide, reduce tropical deforestation to zero and replant forests.

--Expand no-till farming worldwide to reduce plowing and keep carbon in the soil.