The United Nations estimates that more than 20 million people in over a dozen countries are currently facing severe famine and starvation — the largest risk of mass starvation since 2011 when 260,000 people in the region died before famine was officially declared.

Causes for the perfect-storm of instability precipitating the famine include a civil war in South Sudan, a Boko Haram insurgency in northeast Nigeria, and a severe three-year drought in the Horn of Africa.

The countries hardest hit so far are Nigeria, Somalia, South Sudan, and Yemen, where a combination of drought and military conflict have put millions of lives at stake.

The United Nations already declared famine in some areas of South Sudan in February, although UNHCR spokesman Adrian Edwards said that “a further 1 million people are now on the brink of famine”.

Edwards also said the UN is “raising our alarm level further by today warning that the risk of mass deaths from starvation among populations in the Horn of Africa, Yemen and Nigeria is growing.”

He added that a catastrophe potentially much worse than the 2011 failure to respond “is fast becoming an inevitability”, arguing that “the problem we have with humanitarian crises in sub-Saharan Africa is that they tend to get overlooked until things are too late. A repeat must be avoided at all costs.”

Of course, feeding starving people in Africa isn’t free — someone has to pick up the tab.

That’s where things get tricky. The UN has appealed for $4.4 billion dollars to help the four most affected countries, but they’ve received less than $984 million so far.

Additionally, much of northeast Nigeria was inaccessible until recently due to the presence of Boko Haram militants. When UN workers have gained access, estimates of those at risk of famine have gone up as they discovered the severity of food insecurity in the region.

In March, the International Committee of the Red Cross issued a desperate plea for help — saying “The humanitarian situations in Yemen, Somalia, South Sudan and Nigera are verging on catastrophic.”

“With millions facing famine, we must address the root causes of this desperate situation — and time is running out.”

According to the ICRC, hospitals in Yemen have reported a 150% increase in child malnutrition cases, one-in-three households in South Sudan urgently needs food, 300,000 Nigerian children are expected to suffer from severe acute malnutrition over the next year, and 23% more children under the age of five in Somalia are being treated for malnutrition than last year.

The Committee’s statement included an assignment of blame for the catastrophe, in which they said “Climate has played a part in what’s going on, but the actions of people are primarily to blame. All four countries and their peoples have endured years of violence and suffering. The protracted conflict is what lies at the root of these humanitarian crises.”