At least 10 million poor people face hunger this year and next because of droughts and erratic rains linked to record global temperatures and an expected "super" version of the evolving El Nino weather pattern, aid charity Oxfam has warned.

In Ethiopia alone, 4.5 million people need food aid because a combination of El Nino and long-term climate change has made the rainy season more unpredictable, according to United Nations agencies.

El Nino, caused by Pacific Ocean warming, leads to dry weather in some parts of the world and causes floods in others.

This year the phenomenon is expected to peak between October and January and could turn into one of the strongest on record. The last "super El Nino" was in 1997-8.

"Rice and maize crops are both at risk, with serious implications for millions of poor people from Southern Africa to Central America who are dependent on these staples," Mark Goldring, Oxfam GB's chief executive, said in a statement on Thursday.

A scorching drought has ravaged crops in southern Africa already, with South Africa's key maize crop falling by a third and poor yields set to continue into the southern hemisphere summer, according to the country's weather service.

In neighbouring Zimbabwe, where the maize harvest is 35 per cent below average, the government blamed the drought-stricken farm sector for a halving of its economic growth forecast in July.

Harvests in Central America have fallen by as much as 60 per cent for maize and 80 per cent for beans this year due to prolonged dry spells linked to El Nino, according to the U.N. Food and Agriculture Organization.

Southeast Asia is also affected, Oxfam said.

Warming seas could double the frequency of the most powerful El Ninos, the report noted.

As world leaders prepare for a U.N. summit on climate change in Paris in December, increasing climatic disruption, driven by rising temperatures, threatens to increase the likelihood of humanitarian emergencies at a time when the aid system is already under enormous strain, Oxfam said.

"Governments and agencies need to act rapidly to avert humanitarian disasters in the next year," said Goldring.

"This should serve as a wake-up call for them to agree a global deal to tackle climate change." – Reuters