UNITED NATIONS - World leaders have called for collective efforts to tackle the urgent global challenges posed by climate change as the world is at a critical moment in the pursuit of green and sustainable development.

"While COVID-19 is a devastating pandemic, which caught the world unaware and ill-prepared, climate change is a phenomenon we are well aware of, and can mitigate against its repercussions," President Mokgweetsi Masisi of Botswana said Thursday, addressing the ongoing general debate of the 75th session of the United Nations General Assembly.

"We long declared climate change an existential threat, and committed to restrain its rapid devastation," he told the assembly, adding the international community should re-double efforts to mitigate its negative effects.

Masisi also appealed for nations to attach great importance to climate action.

Estonian President Kersti Kaljulaid said digital solutions can serve the fight against climate change and help secure a more resilient and sustainable world.

"Smart grids, matching power supply and demand, developing digital solutions for that, is big part of CO2 neutral economy to come," Kaljulaid said at the general debate.

"We must balance this by not only developing reserve capacities like pump storage or hydrogen, but also to even out peak demands by smart consumption management," she added.

Slovenian President Borut Pahor called for world attention and continued commitment to Sustainable Development Goals and environmental protection.

"My personal advocacy to environmental protection is both global and local, based on introducing public debates on climate change, establishing committee for climate policy and supporting youth movements," said Pahor, adding "the best means of addressing the current global threats is effective multilateralism."

Gambian President Adama Barrow said "it is essential and most urgent to accelerate the implementation of our global commitments on Financing for Development and the Paris Agreement on Climate Change."

"The disrespect for nature has caused climate changes with negative impact on humankind," warned Timor-Leste President Fransisco Guterres.

"The destruction of ecosystems and biodiversity is linked to the new diseases of which COVID-19 is an illustration," Guterres said.

Convened on Tuesday, the theme of this year's general debate is "The future we want, the United Nations we need: reaffirming our collective commitment to multilateralism -- confronting COVID-19 through effective multilateral action."

Climate change and sustainable development in the context of pandemic are among the key issues that world leaders have touched upon.

"We must not lose sight of the even more persistent existential threat to humanity, climate change," Finnish President Sauli Niinisto told the assembly on Wednesday.

"The urgency of bold and swift climate action is growing by the day. Our commitments to the Paris Agreement must prevail. We must redouble our efforts for their implementation," Niinisto urged.

Noting that the climate change is "another existential crisis for our civilization," Kazakh President Kassym-Jomart Tokayev called for nations to "unite around the UN's six climate positive actions."

"To address these global crises, we need to restore an atmosphere of trust between member states and strengthen multilateral institutions," Tokayev said.