The report, from Christian humanitarian organisation World Vision, also exposes the devastating impacts of long-term poor diet and food shortages on populations.
Key findings show 928 million people faced ‘severe’ food insecurity in 2020, with more than a quarter of the world’s children affected by malnutrition.
Nearly half of deaths in children under five years old – more than 2.5 million globally – are related to malnutrition.
Meanwhile, around one in eight people worldwide is at increasing risk of famine in coming years.
Increasingly frequent extreme weather events, brought on by climate change, are leading to cycles of drought and flooding which hamper farming.
This is especially disastrous for communities which are too poor to provide alternative food after crop failures.
The report highlights how a lack of healthy food can seriously impact the development of young children, leading to conditions which affect not only their own bodies but also the future of whole communities.
The aid organisation is calling for the threat to food and agriculture to be prioritised in actions to tackle the climate crisis.
Mark Sheard, chief executive of World Vision UK, said: “Weaker bodies are less able to perform necessary work needed for abundant agriculture.
“This means that food insecurity is a compounding issue which worsens year-on-year and generation-by-generation.
“World leaders must put food and nutrition at the top of the priority list when discussing climate change or risk condemning the world’s most vulnerable children to hunger, malnutrition and death.”
Speaking at a World Vision panel event at COP26 in Glasgow, Nick Dyer, the UK’s special envoy for famine prevention, confirmed the problem.
He said: “Climate Change is exacerbating food insecurity. There is absolutely no doubt about that.
“I have seen some of the worst impacts that an unstable climate can have on a community’s access to ample nutritious food.”
Mr Sheard said generational malnutrition is a serious and growing problem, which causes a range of health issues – from anemia to stunted growth of unborn babies, birth complications and an inability for mothers to produce enough milk to feed their newborns.
“There are sadly more than 45 million people who are severely acutely malnourished,” he said.
“They are being pushed into a state of wasting, a condition defined by being severely underweight.
“This can also result in people having immune systems which are too weak, leaving them vulnerable to developmental delays, disease and, ultimately, death.
“This is the real and harsh consequences of global hunger, and predictions seem to suggest that it will only get worse.”
He believes COP26 isa key opportunity for world leaders to place global hunger at the centre of climate change policy.
He said: “Agriculture and access to nutritious food must be a core consideration for climate mitigation activity if we hope to properly address global hunger.
“This is the micro consequence of a warming planet as extreme weather conditions threaten to wash away people’s crops and wash away their futures.
“Children did not create these problems but they will suffer the consequences of our inactivity.
“We owe them better.”