The United Nations has launched a record $2.7 billion humanitarian appeal as 2017 assistance for the Sahel region hit by Boko Haram as poverty, conflict and climate change will leave 15 million people across belt in need of life-saving.

Around 40 per cent of the money will be used to help some seven million people in Nigeria affected by the jihadist group Boko Haram’s seven-year insurgency, according to the UN Office for the Coordination of Humanitarian Affairs (OCHA).

OCHA has increased its appeal for eight countries in the semi-arid band stretching from Senegal to Chad more than tenfold in as many years, but each year funding has fallen short.

This year’s $2billion appeal has been less than half-funded to date.

“The lack of funding this year has worsened the humanitarian needs of 11 million people in the Lake Chad Basin, where the crisis is most acute,” the UN’s Regional Humanitarian Coordinator, Toby Lanzer, said.

One in six people across the Sahel are hungry, while in many communities throughout the region, a fifth of children under the age of five are malnourished, according to figures from OCHA.

In addition to violence involving militant groups, climate change is a major factor behind the growing number of vulnerable people across the region, as increasingly unpredictable rainfall patterns disrupt local food production, aid workers say.

“We are adapting by equipping farmers and policymakers with climate information and early warning forecasts, and being prepared not just weeks, but months and years ahead,” Africa Regional Coordinator of the UN-led Global Framework for Climate Services, Arame Tall, said.

The vast number of vulnerable people, and those forced from their homes by violence across the Sahel, some 4.5 million, is fuelling migration to Europe and driving more young men to join militant groups, according to the UN.

Nigeria is the main country of origin for migrants arriving in Italy by sea this year, says the International Organization for Migration (IOM).

At least, 34,000 Nigerians have crossed from Libya so far in 2016, up from 22,200 last year, IOM data shows.

“Families and communities are separated and split, education is disrupted, and dreams of success dashed,” Regional Director of the Peace Building Group Inter-Peace, Anne Moltes said.

“If there is no structure, young men leave to find figures of authority elsewhere,” she said at the launch of the appeal.