By Ania Lichtarowicz
BBC News, St Louis, Missouri
The world will have 100 million extra hungry people by 2015, scientists say.
Parts of Kenya are facing severe food shortages
They were speaking at the annual meeting of the American Association for the Advancement of Science (AAAS).
Despite great improvements in food availability in the 1960s and 1970s, these trends are reversing in many developing countries, they say.
The United Nations' goal of halving hunger by 2015 looks unattainable without new technologies and greater financial investment, they add.
Ten pre-school children die every minute from malnutrition and this number has not changed since the early 1980s despite global promises.
Professor Per Pinstrup-Anderson, from Cornell University in New York, says that improving agriculture is the key.
"When you put money in the hands of farmers that money is spent on creating employment and reducing poverty elsewhere," he said.
"We have found in our research that for every dollar you invest in agricultural research you generate about $6 of additional income among the farmers and about $15 of additional economic growth in the society as a whole. Much of that will help poor people in those countries."
More commitment needed
There is some good news though.
China and Vietnam have considerably increased food availability and cut the number of people who do not get enough food.
But this has only been achieved by improving infrastructure and using technology including GM crops to increase yields - which is missing in many other countries.
For instance, east Kenya last year faced a famine. In the west of the country there was an excess of corn, but this was shipped to Europe because neither the means nor the money was available to get the corn to those starving in the east.
Scientists at the AAAS meeting in St Louis, Missouri, say situations like this will continue to occur unless governments in developing countries increase their commitments to ending poverty and hunger.