New agricultural technology has enabled global food supplies to outstrip population growth, driving down the number of hungry people around the world from just over 1 billion in 1992 to 842 million today — a 17 percent drop. But food shortages and undernourishment remain huge problems in developing countries. Hunger stems from weather-related disasters such as droughts and floods, as well as from war, poverty, overpopulation, poor farming practices, government corruption, difficulties transporting food to markets, climate change and waste. Hunger is severest in sub-Saharan Africa, where 25 percent of the population is undernourished. Developed countries and humanitarian organizations have become proficient at providing emergency relief and promoting higher-yield, environmentally friendly agricultural practices, but the outlook on global hunger remains murky. Experts expect an expanding global population and growing economic affluence in developing countries to increase the demand for food, even as climate change hampers the planet's ability to feed itself.