The study finds that a wide range of existing technologies could be immediately deployed to prevent global carbon dioxide (CO2) emissions from increasing over the next 50 years.

The finding "explodes the idea that we need to do research for a long time before getting started," said coauthor Stephen Pacala, a Princeton University professor of ecology and evolutionary biology.

Pacala and his Princeton colleague Robert Socolow identified 15 technologies to restrain carbon emissions, including carbon sequestration, greater fuel efficiency and energy conservation, improved agricultural and forestry practices, as well as faster deployment of wind, solar and nuclear energy.

The Himalayas and the Tibetan Plateau as photographed from a NASA satellite. Glaciers in these highest mountains in the world are melting at a rapid rate. (Photo courtesy NASA)

"If we decide to act, we will need to reduce carbon emissions across the whole global economy," said Socolow, a professor of mechanical and aerospace engineering. "Fortunately, we have the tools to do this, especially if we think in terms of 50 year campaigns, not instant solutions."

Pacala and Socolow caution that even if existing technologies are deployed to curb carbon emissions, scientists must continue researching alternative technologies because new measures will be required after 50 years.

By that time, the scientists said, some of the 15 technologies will have reached their full potential and may not be able to keep up with increasing energy demand.

Current global emissions of carbon are some seven billion tons a year - a total that is estimated to climb to 14 billion tons per year over the next 50 years as the world population increases and people consume more energy.

The burning of fossil fuels - such as coal, oil, and natural gas - is the major source of human generated greenhouse gas emissions.

In their paper, Pacala and Socolow show how each of the 15 options they identified could prevent one billion tons a year worth of carbon emissions by 2054 by curbing the world's consumption of fossil fuels.

Limiting carbon emissions to current levels for 50 years would put the world on a track to stabilize the concentration of CO2 in the atmosphere at about 500 parts per million, the authors said.

Even that total would be roughly a doubling of the carbon dioxide content compared to the pre-industrial level of 280 parts per million.

Coal-fired power plants are a major source of carbon dioxide emissions. (Photo courtesy NASA)

Climate change skeptics say the analysis is flawed and does not consider the economic and political costs of its recommendations.

"The study basically says that if you coerce everybody to use a lot less energy and don't care about the cost, you can significantly reduce emissions," said Marlo Lewis, a senior fellow at the Competitive Enterprise Institute, a conservative think tank. "We needed Princeton University to tell us that?"

There is little doubt the options put forth in the paper are lofty - and some may not sit well with environmentalists.

One strategy calls for converting 1,400 coal fired electric plants to natural gas.

Another calls for doubling the current global nuclear capacity to replace electricity generated by burning coal.

Pacala and Socolow readily acknowledge that they did not analyze the costs of implementation, but they contend there would likely be economic benefits and note they are laying out an array of options for policymakers.

"We will have to spend real money," Socolow said, "but addressing the global carbon problem now will provide a tremendous stimulus to the economy and will promote the development of needed international institutions, while averting the most serious environmental consequences."

Economic benefits would likely come from the creation of new industries, the reduction of U.S. dependence on foreign oil and decreases in other pollution control expenses associated with burning coal and other fossil fuels.

Automobiles are another major source of greenhouse gas emissions. (Photo courtesy FreeFoto)

Research published in "Science" last month found the oceans are taking on increased amounts of carbon from the atmospheric and are becoming more acidic as a result - scientists warn this could harm marine food chains and alter the oceans in ways not yet understood.

Another study, also published in Friday's edition of "Science," warned that rising greenhouse gas emissions will result in hotter, longer and more severe heat waves.

There is ample cause for concern and for action, Pacala said, including current observations of change, such as warming temperatures and the melting of ancient ice in glaciers.

Investigations of the Earth's climate over the last million years show that various factors, such as changing carbon dioxide levels, tend to reinforce each other and cause the temperature "to switch all at once" as it has during previous ice ages.

And the computer models that explain past climate behavior and predict future changes indicate that increasing the level of carbon dioxide will cause long term warming.

"The models are not perfect but they are based on sound principles," Pacala said. "You put it all together and you say, 'This looks dangerous.' And then when you find that we already have the technology to deal with it, we say, 'Why not?'"