Remote parts of Nigeria are gripped by a famine, one that will probably continue for months. Boko Haram has triggered one of the world's worst humanitarian disasters there with scorched-earth policies that laid waste to an area the size of the U.S. state of Georgia. But it took some time for the world to find out. The Famine Early Warning Systems Network declared several months after the fact that famine had broken out in the northeast. At least 2,000 children had died, it added. The word "famine" has become a technical term, and declaring one requires on-the-ground accounting of the deaths of children under 5, adult mortality and food shortages - data often impossible to get in areas where there is fighting. Even in places that can be safely reached, Africa's map of hunger is lit up with red, signaling a state of emergency from Nigeria to Somalia to South Sudan, with the crises expected to worsen in coming months. Donors have continued to give, but the number of people who need help has increased so sharply that they cannot keep up. Desperately hungry families have to make rations from the World Food Program stretch twice as far as they're intended - or even further - in Nigeria, South Sudan, Somalia, Uganda, Kenya, Chad, Madagascar, Malawi, the Central African Republic, Burundi, Cameroon and elsewhere in southern Africa. The vast scale of the emergency, unfolding in tandem with the crisis in Syria, has put massive strain on the global humanitarian system. It comes at a time when aid agencies had hoped to pursue an ambitious program laid out by the U.N. for achieving its sustainable development goals, which include eradicating poverty and hunger by 2030. African farmers scrape out a living in some of the harshest places on Earth. Climate change has made it tougher, with successive droughts and crop failures in many parts of Africa. On top of that, the 2015-16 El Nino led to severe drought, poor harvests and mass deaths of cattle and wildlife. Meanwhile, fighting has caused humanitarian emergencies in several countries, including Nigeria, Somalia and South Sudan. Just over 10 years ago, international humanitarian agencies launched a system to define famine called the Integrated Food Security Phase Classification. The aim was to establish a consistent definition, so that the world would never again turn its back on catastrophic starvation. In Nigeria, one of Africa's worst crises, 4.7 million people need food aid in the northeast. Boko Haram attacks have prevented farmers from planting, and the emergency will probably drag on until late next year. The World Food Program has raised only $65 million of the $208 million needed to avert catastrophe in Nigeria. The disaster also affects Nigeria's neighbors in the Lake Chad Basin, including Chad, Cameroon and Niger. In all four countries, half a million children are malnourished and 11 million people will need emergency relief this year. A toxic mix of war and economic collapse threatens to tip South Sudan into famine. Fighting spread across South Sudan with July's collapse of a peace deal signed in August to end the civil war that broke out in 2013. Farmers in South Sudan's most fertile region cannot plant crops, food markets are often closed and roads are frequently blocked, cutting food imports from neighboring countries. Even when food does reach markets, few people can afford it, with inflation above 800 percent - the highest in the world. About 4.6 million people need emergency food aid, and 3 million have fled their homes because of fighting. The worst may lie ahead. "All available indicators point to an unprecedented deterioration of the food security situation across South Sudan in 2017. The risk of famine is real for thousands of people," the U.N. Food and Agriculture Organization warned. In parts of Somalia, hit by repeated droughts, vegetation levels are now the worst ever recorded, with the drought set to worsen, according to the U.N. That means withered crops, failed harvests and a likely hunger emergency ahead. Somalia is fragile after more than three decades of war and continuing attacks by an al-Qaida-linked extremist group, al-Shabab. As stock animals die and food prices soar, families are facing severe distress. In parts of southern Madagascar, a three-year drought has seen crops fail year after year. Some families have been surviving on prickly pear cactus. Waterholes dried up in many areas, forcing impoverished families to spend what little they have on water. Many have sold their livestock and even their pots and pans to buy water and food. And severe drought in Zimbabwe has left the population vulnerable to hunger and poverty. Local government officials, who control the distribution of humanitarian aid, have denied assistance to opposition figures or strongholds, according to a report by the Zimbabwean Human Rights Commission released in October. That month, the World Food Program announced that it had received more than 1,000 complaints over food distribution in the previous six months, according to local reports. Neighboring Malawi and much of southern Africa have also been hit hard by the drought.