Nine African heads of states attended Monday's opening session of the UN's COP15 talks to fight desertification and land degradation  that have devastated large swathes of the continent amid climate change .

The United Nations Convention to Combat Desertification (UNCCD), 196 countries plus the European Union -- is meeting for the first time in three years, in Abidjan.

Decades of unsustainable agriculture have depleted soils worldwide and accelerated both global warming and species loss, the UNCCD says, with an estimated 40 percent of land degraded globally.

"Our summit is taking place in the context of the climate emergency which harshly impacts our land management policies and exacerbates drought," Ivory Coast President Alassane Ouattara announced.

"Our people put great hope in us,. We don't have the right to disappoint them.

"Let us act swiftly, let us act together to give new life to our lands," he urged.

Nigeria's Muhammadu Buhari, Niger's  Mohamed Bazoum and DR Congo's Felix Tshisekedi were among the continent's leaders listening to the Ivorian host.

French President Emmanuel Macron was to address the gathering by videoconference later in the day.

Ouattara presented  the Abidjan Initiative to raise $1.5 billion over five years to restore Ivory Coast's "degraded forest eco-systems" and promote sustainable soil management.

Ivory Coast is among numerous African nations badly affected by desertification. Forest cover has fallen by 80 percent since 1900 -- from 16 million hectares to just 2.9 million last year.

"At the current rate, our forest could totally disappear by 2050," Ouattara warned.

COP15 runs until May 20 and is due to hear new proposals to try to halt the spread of desertification and deteriorating land quality.

The conference will pay particular attention to the restoration of one billion hectares of degraded land by 2030, future-proofing land use and drought resilience, the UNCCD said.

Debate is expected to include the question of the "Great Green Wall" scheme to restore 100 million hectares of arid land from Senegal in the west of Africa to Djibouti in the east by 2030.