text: (CNN) Americans will need to cut their average consumption of beef by about 40% and Europeans by 22%, for the world to continue to feed the 10 billion people expected to live on this planet in 2050, according to a new report.
  That means each person could have about a burger and a half each week.
  This calculation comes from the World Resources Institute, a global research nonprofit that supports better use of natural resources to sustain a growing population. Its research looks at agriculture, the climate crisis, poverty and gender, among other topics.
  Its final "Creating a Sustainable Food Future" report released Wednesday takes a closer look at the gaps in food production and global demand and makes several concrete recommendations on how to prevent a catastrophe.
  Eating less beef is one such suggestion in the 568-page report.
  About 9.8 billion people will live on the planet by 2050, that's up from 7 billion people in 2010. Demand for food is projected to outpace population growth, increasing by more than 50% as people's incomes in the developing world are expected to increase, according to the report.
  The demand for meat and dairy is expected to rise even faster, by nearly 70%. The global demand for ruminant meat, meaning beef, sheep and goat, is expected to be even higher, at 88%.
  But to keep up with food demands overall, the report predicts farmers are going to have to produce 56% more crop calories than in 2010 -- and that means that land nearly twice the size of India will be needed.
  Closing these gaps is "harder than often recognized," according to the report.
  The authors suggest there are several ways to keep people from starving and to keep the climate crisis at bay, but the most impactful way to do this may be to cut the consumption of ruminant meat.
  Beef, goat and sheep production use up a lot of land and resources. It requires more than 20 times more land and generates more than 20 times more greenhouse gas emissions than pulses, a plant that is in the legume family -- dry beans, dry peas, chickpeas, lentils -- per gram of protein, according to the report.
  Cows grow and reproduce slower than pigs and poultry and that means they need to eat a lot more and need more land and water.
  Beef alone is responsible for 41% of livestock greenhouse gas emissions, and that livestock accounts for 14.5% of total global emissions, according to the United Nations. That's more than direct emissions from the transportation sector.
  In the United States, beef only accounts for about 3% of the calories in the average US diet, but it uses 43% of US land used for agriculture, according to the report.
  The current report suggests people who live in countries like the United States that eat a lot of beef, compared to the rest of the world, don't need to give up hamburgers, but they will need to cut back how many they eat.
  In 2010, Americans ate 59.3 pounds of beef, according to the US Department of Agriculture. To get to a 40% reduction that would mean eating 23.72 pounds of beef for the year. With an average hamburger patty being about 4 ounces, you could have just about a burger and a half worth of beef a week.
  The report suggests this is doable and necessary, although "the challenges are formidable." It points to eating trends in the United States as an example. In the late 1970s Americans were eating a lot more beef than they do today.
  In 1976, Americans ate more than 94 pounds of beef a year. In 2018, it was 57.2 pounds.
  Switching to plant-based foods would help the environment the most, but most climate and land-use benefits would still happen even if people switched from eating beef to chicken and pork, the report finds.
  The National Cattlemen's Beef Association takes issue with the report.
  "Beef is both sustainable and nourishing. Environmentally, cattle play a unique role in our food system because they upgrade inedible plants to high-quality protein. Protein that, decades of research shows, promotes health and helps prevent human nutrient deficiencies," said Hillary Makens, the director of media relations for the association in an emailed statement.
  "Most people are already eating beef within global dietary guidelines, so we assert the biggest opportunity for a healthy sustainable diet will come from reducing food waste, eating fewer empty calories and enjoying more balanced meals. History and well-established research have consistently shown that science-based advancements and practical, balanced dietary patterns promote health and sustainability, not eliminating single foods, like beef."
  Other agencies have suggested changing the meat in our diets could make a real dent in the fight against the climate crisis. The UN Intergovernmental Panel on Climate Change report published in 2018 said changing diets globally could contribute significantly to what's needed to keep global temperatures from rising 2°C above pre-industrial levels.
  This current report notes that there have been an increasing number of companies that are investing in beef alternatives, and a huge surge in demand for meat substitutes made from plant-based proteins.
  Hamburger chains are piloting burgers made from fake meat or trying to reduce their beef content, adding other protein such as mushrooms. Several companies are even developing lab-grown meat.
  While the marketplace might reduce the demand for beef, governments could also take steps to make other menu items more desirable, according to the report. For example, governments could phase out subsides for meat and dairy production or start taxing beef, making it more expensive.
  Eating less red meat might be good for the planet, but it could also help your health. Earlier research has found that eating red meat is tied to increased risks of diabetes, heart diseases and some cancers.