U.N. chief Antonio Guterres joined African leaders on Tuesday in demanding urgent reforms to the "outdated and unfair" global financial system, speaking at a landmark climate summit in Kenya aimed at showcasing the continent's green potential.

The Nairobi summit hopes to boost investment in renewables, with the UAE on Tuesday pledging $4.5 billion to accelerate Africa's clean energy transition as the continent's leaders look to reshape its economic narrative.

The three-day conference, which began Monday, has attracted heads of state, government and industry leaders from across Africa, as well as EU chief Ursula von der Leyen and U.S. climate envoy John Kerry.