In the 1973 sci-fi classic "Soylent Green," Charlton Heston's character faces a dystopian future in which a protein made from plankton is grown in test tubes to sustain an overpopulated Earth.

A new National Academies of Sciences study from 18 top scientists suggests that a similar cultured protein will be needed in the not-too-distant future to deal with the problems of population growth and climate change.

The new Department of Energy-funded study on environmental engineering released Monday doesn't suggest that switching the global diet to a lab-made protein will lead to the horrifying climax of "Soylent Green", but it does suggest that beef will have to be made more scarce.

The report finds that livestock farming could be responsible for as much as 14.5 percent of all man-made greenhouse gas emissions, which are blamed for raising the temperature of the Earth. Cattle alone is responsible for almost two-thirds of that 14.5 percent, the study says.

Beef and dairy farming also require far more water per unit of protein produced compared to plant-based protein equivalents, the study says.

The study estimates that global meat production could grow as much as 12 percent by 2026 due to population growth and increasing demand due to rising standards of living in lower- and middle-income countries.

The environmental effects of this increase could be reduced by shifting global dietary patterns that de-emphasize animal-based protein, especially beef.

Not unlike "Soylent Green," the National Academies report says a variety of meatless protein products, including protein products grown from "animal and plant tissue cells in culture, are becoming available."

If the products can be affordably produced at scale and be accepted by consumers, "they could reduce the demand for livestock, thereby decreasing the land, energy, and water requirements of animal-sourced protein and its associated environmental impacts while expanding food availability," the report says.

Some estimates show that such dietary changes could allow 30 percent more people to get fed with the same agricultural land and crop patterns.

Conservation groups and others will be urging changes to the agriculture industry to curb emissions at this week's United Nations climate meeting where the future of the Paris climate accord will be discussed.

It is something that has been difficult for some governments to approach, but needs to be considered to keep the Earth from rising 1.5 degrees over the next decade, Dr. Nils A. Rokke, executive vice president of sustainability at Scandinavia's largest research institute called SINTEF, told the Washington Examiner from Norway.

Rokke will be attending the climate summit in Katowice, Poland, where he hopes to raise the issue of transitioning from beef and cattle to some alternative form of protein.

"This goes into the lifestyles of people," said Rokke, who admits to enjoying steak. But if everyone is enjoying steak around the world, there "is going to be a huge problem there," even if measures are taken to breed different types of livestock.