France will give African countries two billion euros ($2.1 billion) over the next four years to develop renewable energy and replace the fossil fuels that drive global warming, President Francois Hollande said Tuesday.

"France will devote six billion euros between 2016 and 2020 for electricity provision on the continent," he said at a meeting of African leaders on the sidelines of a UN climate conference in Paris.

"Two billion euros will be spent on renewable energy" -- double the amount France provided in the preceding five years, he said.

Hollande spoke a day after more than 150 world leaders gathered for the start of the 12-day meeting tasked with beating back the threat of global warming and helping poor countries cope with its impacts.

"France wants to lead by example," the French president said of his country's commitment to boosting Africa's green energy transition.

Helping the continent develop renewables is also a way to ensure its security, he said at his meeting with more than a dozen heads of state and government.

"Though Africa is not responsible for emitting greenhouse gases, it is suffering the consequences of climate change," Holland said.

"The world owes an ecological debt to the African continent."

African countries generate four percent of global greenhouse gases per year, a quarter of that coming from economic giant South Africa alone.

African leaders at the meeting called on rich countries to step up their efforts.

"A lot more has to be done", said Nkosazana Dlamini-Zuma, head of the African Union commission.

Climate impacts were already severe, she said, pointing to "a drought without precedent for decades."

Lake Chad, she noted, has seen it surface shrink to a tenth in just 60 years.

Hollande did not specify how the four billion euros not earmarked for renewables would be allocated.