Timothy D. Searchinger is a research scholar at Princeton University and a senior fellow of the World Resources Institute. Follow him on Twitter: @Tsearchinger . Richard Waite is a research associate at the World Resources Institute. Twitter: @waiterich . The opinions expressed in this commentary are their own. View more opinion articles at CNN.

(CNN) Burger King has promised to go national by the end of the year with its Impossible Whopper, a plant-based patty that tastes like the real thing. Other fast-food companies have also started selling Impossible burgers, and other plant-based burgers that really taste like hamburgers and will be on sale in more grocery stores soon. These developments are a whopping big deal, even historic, because of their potential to redress climate change and save forests.

What's the environmental beef with beef? As many people know, the stomachs of cattle produce methane, a powerful greenhouse gas that cattle emit mostly through burping. The manure cattle leave on grazing land also produces a lot of nitrous oxide, another powerful greenhouse gas. But the biggest challenge is that producing beef requires a lot of land.

On a global basis, it takes between 50 and 100 calories of some kind of feed -- mostly grass -- to produce one calorie of beef. Because it takes land to produce that feed, it ultimately takes far more land to feed people with beef than with almost any other kind of food.

Globally, cattle and other grazing animals use an area roughly twice the area of global cropland, or about four times the size of the continental United States. Roughly 40% of this grazing land was originally forest. As beef consumption expands, more tropical forests and woody savannas are converted to grassland (and a little cropland) to produce it, and the conversion releases vast quantities of carbon dioxide from the carbon otherwise stored in trees and other vegetation.

Beef uses roughly 20 times more land and releases 20 times more greenhouse gases for the same amount of protein as common plant proteins such as beans, according to our published calculations. Compared to dairy, the land use and emissions are roughly five times greater, and compared to chicken and pork, roughly 10 times.

Virtually all strategies for stopping global warming require that the world immediately stop clearing forests to produce more food, and most require reforesting vast areas of land even in the next few decades. To do that, the world needs to feed itself with food produced on the same or less land.

Yet even if agricultural productivity continues to increase as it has in the last 50 years, the expected rise in world population -- and a growing ability to afford meat among people who eat little meat and hardly any beef now -- means farmland will continue to expand and vast areas of forests will be cleared to meet rising food demand.

One way to get more beef without clearing more forests is to produce more meat from the same land. Improved grazing practices and overall livestock production around the world are therefore vitally important, and American or other farmers who produce beef well will remain needed.

Yet even if most of the land that can produce beef well doubles its output per acre, that will probably not be enough. A recent study we co-authored for the World Resources Institute, the World Bank and others explores possible paths to feed the world while sparing forests and solving climate change. Even with such productivity gains by 2050, our study found that big beef-eaters need to curb their consumption. In our main path to success, Americans on average need to cut their overall beef consumption in half, down from the equivalent of three hamburgers per week to 1½.

From an environmental standpoint, that does not mean beef consumption has to end. In fact, beef and dairy cattle eat a variety of feeds, such as brewer's yeasts and citrus pulp, that are wastes from other agriculture production. Cattle can feed on native grazing land that with good management can continue to store carbon and provide significant habitat.

So eliminating beef is neither the goal nor realistically at stake. The point is to hold down its growth. The world has long fully exploited native grazing areas and turned to clearing forests to meet demand. Because the beef market is global, every person who eats less beef makes it possible to save more forests.

That is why moderating beef consumption is so important. Those who say reducing beef and other dietary choices don't do much to tackle climate change compared to changing energy sources don't typically consider the greenhouse gas consequences of land use. When land use is factored in, we have calculated that what Americans eat generates almost as many emissions as the energy they consume. And beef generates almost half the emissions from the American diet although it provides just 3% of the calories.

In fact, even if global projections turn out to be wrong and the world does reduce its farmland, every acre that isn't needed to produce beef would still mean an additional acre that could return to forest, provide habitat and take carbon out of the air.

Which takes us back to the Impossible Whopper. In just a few years of effort, small companies have made products that we can testify from personal experience should fully fool the taste buds of most Americans. The Impossible Burger should soon be in our grocery stores looking just like hamburger meat. While these products cost a little more today, within a few years, the far fewer resources they require should make them cheaper than beef, which will enable them to spread around the world.

These companies also claim to be making progress on other meat and dairy substitutes. While they may not soon fully replicate the experience we and others enjoy of eating a great steak or pork loin, they don't have to. By replacing much of the meat we eat in minced and processed form, these innovations can still make it possible to restore large parts of the world's forests.

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For plant-based burgers, the niche market of people who wish to eat less or no meat has enabled companies to get a strong start. For other needed innovations in food systems, such as more efficient fertilizers, government regulations may be needed. Either way, this announcement from Burger King increases confidence that with the right push, innovators can provide the world with cost-effective ways to tackle climate change and create a sustainable food future.