Yemen is now the world's largest humanitarian crisis. Here's what I've learned. There is a war going on in Yemen and it's been going on for 5 years. There was a ceasefire in April but the conflicts roar on at full speed. All sides involved must cease violating the laws of war and put an end to this entirely man-made catastrophe. U.N. aid chief Mark Lowcock said, "Is the world ready simply to watch Yemen fall off the cliff?" A few weeks ago there was a donor conference but only raised $1.35 billion of the $2.4 billion they need. 24 million Yemenis depend on protection or humanitarian aid for survival. One third of the population – 10 million people – are only a step away from famine. The only real hope to resolving Yemen's humanitarian crisis is for these sides to negotiate an end to this war. But until then, let's help the organization's who are on the ground helping as much as they can.