Most people assume hunger exists in poor communities because there’s not enough food. But that’s usually the lesser problem. Really, it’s just about getting food to the people who need it.

“The problem of undernourishment and hidden hunger around the globe is a distribution problem rather than a production one,” says an important new paper on global food waste published in Environmental Science & Technology.

A systematic study, from the Potsdam Institute, says we wasted 510 kilocalories per person per day in 2010, up from 310 kilocalories in 1965. Generally, societies are getting much better at producing food: there’s 20% more food available than the global population strictly needs. Most places, even undernourished places, have a raw surplus of food. The problem is, one third of production is either not used productively, or it’s not used to feed the world’s underfed.

“Undernourishment may prevail in a country with food surplus due to income inequality and poverty, resulting in disparity in food security within the country,” the paper says. For example, India has a nominal food surplus of 210 kcal/per person/day, yet it has the second highest number of undernourished people in the world.

“To eliminate hunger, countries with food deficits at first need to increase their food availability, while other countries need to improve their food distribution systems,” the paper says. Only a few countries have an actual food deficit (both what they grow and import), including Zambia, Haiti, and Tajikistan.

Potsdam defines food waste as the gap between food availability and the average energy requirement (based on body weight) of a person in a particular country. (An American has a higher energy requirement than a Chinese, for instance.) The researchers use this gap to then calculate greenhouse gas emissions associated with that waste. Agriculture accounts for 20% of emissions now. But 14% of these could easily be avoided by better food management and distribution, lead researcher Prajal Pradhan says.

“Inefficiency in the food supply chain needs to be addressed to reduce agricultural related environmental consequences and climate burdens,” the paper concludes. It will also help feed people, reducing the amount of land that needs to be set aside for producing food. The biggest question ahead for the researchers? How exactly to make the food supply chain smarter and more efficient. That’s another story.