UN Secretary General Ban Ki-moon on Friday appointed former Irish President Mary Robinson and Kenyan diplomat Macharia Kamau as special envoys for El Nino and climate.
The El Nino weather phenomenon, which occurs every two to seven years, affects rainfall patterns and causes both drought and flooding.
Its effects can be seen in places like Sudan, where the UN estimates 400,000 people will need food aid due to El Nino-related drought. Neighboring Ethiopia is experiencing its worst drought in 50 years.
The phenomenon has "created massive needs across the world," the UN said in a statement, particularly in east Africa, southern Africa, Central America and the Pacific.
"This year's El Nino is taking place in a world already dramatically affected by climate change. More extreme weather events are expected in the future, and these hit the poorest communities -- those least responsible for climate change -- first and hardest," the statement said.
"Aid is not enough; a longer term approach is required in order to build the resilience of the most vulnerable."
The new special envoys will be responsible for "raising the profile and sounding the alarm," Ban said in the statement.
"It is vital that we scale up our humanitarian response urgently. To do that we need the full support and attention of the international community," he was quoted as saying.
Robinson had previously served as the UN High Commissioner for Human Rights and as Ban's special envoy for climate change.
Kamau is Kenya's ambassador to the United Nations and former president of the United Nations Children's Fund (UNICEF) Board. He was co-chair of the UN General Assembly working group on sustainable development goals, which includes the fight against climate change.