At the launch of its annual Global Humanitarian Overview in Geneva, the UN said providing aid to those in need next year would cost almost 50 billion euros.
The UN asked for a record-breaking amount of aid funding for 2023 on Thursday to cope with soaring humanitarian needs.
Humanitarian agencies at the United Nations (UN) face mammoth costs to tackle a looming famine in east Africa caused by climate change and the fallout from the Ukraine war.
The UN needs 49.6 billion euros next year -- up 25% from the previous year.
This funding will allow the organisation to finance its programmes, helping around 230 million of the most vulnerable people in 68 countries. However, this will still fall short of what is needed, with a total of 339 million people globally expected to require emergency assistance next year.
The largest sums are needed in Afghanistan, followed by Syria, Yemen, Ukraine and Ethiopia.
UN aid chief Martin Griffiths described the required amount of money as "a shocker", pointing out that "the gap between needs and funding is going to grow".
"Next year will ... be the largest humanitarian programme, ever launched globally," he added. "339 million people ... that's a huge and depressing number."
The Brit said that in 2022 the UN had received just under half of the money it needed to save lives and tackle human or natural emergencies.
He pointed out that humanitarian needs experienced a "peak" following the Covid-19 pandemic, but have unfortunately not diminished since.
According to the UN, the funding gap will force humanitarian organisations to make the sad choices between aiding certain populations and not others.
"Droughts and deadly floods are wreaking havoc ... from Pakistan to the Horn of Africa," said Griffiths. "The war in Ukraine has turned part of Europe into a battlefield. More than 100 million people are displaced in the world. And all this on top of the devastation the pandemic has wreaked on the world's poorest."
The UN's funding appeal paints a bleak picture of the state of the world.
At least 222 million people in 53 countries will face acute food insecurity by the end of 2022, while 45 million people in 37 countries are at risk of starvation.
"Five countries are already experiencing what we call near-famine conditions, where we can say ... people are dying because of displacement, food insecurity [or a] lack of food," said Griffiths.
These are Afghanistan, Ethiopia, Haiti, Somalia and South Sudan, a spokesman for the UN's Office for the Coordination of Humanitarian Affairs told AFP.
Climate change is set to only increase risks and vulnerabilities faced by countries around the world, especially poorer ones.
It will fuel droughts, floods, wildfires and other environmental disasters, which look set to trigger refugee crises and conflicts.
By the end of the century, extreme heat could kill as many people as cancer, according to the UN.