Over the past week, we have seen what terrible hunger looks like. The Disasters and Emergencies Committee has launched an appeal in response to the devastating food crisis in East Africa, including famine in parts of South Sudan and possible famine in Somalia. 16 million people are desperately in need. Famine warnings have also been issued for Nigeria and Yemen.
For this to be happening in the 21st century is a damning indictment of our common humanity. While these food shortages have been caused by both conflict and drought, a famine is always the result of either political choices or catastrophic human failure.
In South Sudan, which has been at war since 2013, more than three million people have fled the fighting with nothing; their fields destroyed, they have no supplies to keep them going. They are walking for up to five days through swamps to reach islands of safety; adults are arriving too weak to stand or speak, having survived on nothing more than water lilies.
Ethiopia, Kenya and Somalia have been hit by back-to-back climate shocks, causing devastating shortages of food and water. In Somalia, this situation is worsened by conflict that has led to large-scale displacement, disruption of agriculture and the collapse of normal trading and market activities. And the world has been too slow to wake up and express its outrage.
Have we, the global community, learned nothing from the past? Less than one year after the first World Humanitarian Summit, at which more than 3,000 commitments to action were made, should we hang our heads in shame? Not necessarily - or at least, not yet.
By the time a famine was last declared, in Somalia in July 2011, around 130,000 people were already dead. The response by the international community came too late to save many more; in total, nearly 260,000 people died - half of them children. This time around, with stronger early warning systems, we have a chance to avert the worst if we respond urgently and effectively. There is a better humanitarian presence on the ground, the government is stronger, and while insecurity remains an obstacle, it is not as severe as it was.
We have seen how this is possible. Only last year in Ethiopia, the drought in many places was worse than the terrible drought that we remember in 1985. But because of real economic progress, better preparation and a strong, timely response by the Ethiopian government and international community, suffering was so much lower that it barely hit our screens.
In all of these countries, we can prevent people starving and support them through these crises, but we urgently need two things: funding, and access to the people in need. Those who generously donated £24m to the DEC appeal so far - including £10m in matched funding from the UK Government - are helping with the first.
Meanwhile access remains a challenge in some areas but we are going the extra mile to reach those in need. Last week, Oxfam chartered a small plane and distributed beans, rice and oil in Panyijar in South Sudan. This was very much a last resort - not least because of the expense - but it was the only way to reach these communities and keep them alive.
Emergency measures like this are crucial now, but we also need to help these vulnerable communities build their resilience, so they can cope better with shocks in future. This is difficult in an environment beset by conflict, but even here, the UK public's generosity can and does make a difference. For example, in the town of Nyal in South Sudan's Unity State, the only vegetables available in the market - okra, tomatoes and onions - come from an Oxfam project to support community gardens. Small scale, sure, but it shows what can be done.
On a bigger scale, the social safety-net programme in Kenya, which provides regular cash to extremely poor households in the arid northern counties, has been designed so that when there is a drought or flooding it can provide cash to greater numbers of people. This scheme, and a similar one in Ethiopia have made it easier for people to absorb, cope with, and recover from damages caused by natural disasters; evidence from Ethiopia shows that those covered by the scheme are not hit as hard by droughts.
However, alongside these concrete gains, we need action to tackle the root causes of climate and conflict. East Africa has been buffeted by a series of climate shocks; seven of the past ten years have seen chronic droughts in the Horn of Africa due to poor or failed rains. Action to curb emissions and help communities to adapt is vital if we're to prevent future famines.
On conflict, the international community needs to be clear: starvation is not an acceptable consequence of war. Civilians have the right to life-saving humanitarian aid, and we need our leaders to put pressure on all sides to uphold that right.
In today's increasingly unstable world, such action may seem a long way off but there is a flipside to the grim fact that famines are man-made; it means that we have the power to prevent them.