Delegates at an international conference on the environment have called for accelerated multilateral action to cope with intensifying global environmental crises such as climate change, loss of biodiversity and pollution for sustainable development.

"We are living in a time of turmoil. Our response must demonstrate that multilateral diplomacy can deliver," Leila Benali, president of the United Nations Environment Assembly, said during opening remarks at the sixth session of the assembly in Nairobi, Kenya, on Monday.

"Today, we must accelerate multilateral action to strengthen the environmental foundation of sustainable development."

This year's session of the UNEA, the world's top decision-making body on environment that includes all 193 UN member states, opened at a "critical" time for the planet Earth, with climate change intensifying, 1 million species heading toward extinction, and pollution remaining one of the leading causes of death globally, the United Nations Environment Programme said.

Inger Andersen, executive director of the UNEP, said at the opening ceremony that this year's session has garnered increased global attention and demonstrated more unity, with a record number of more than 5,000 delegates attending.

During the five-day meeting, government leaders are expected to debate 19 draft resolutions on issues including improving air quality, addressing climate change, limiting chemical pollution, countering desertification and ending biodiversity loss. They also plan to renew calls for progress on Sustainable Development Goals.

UNEA resolutions are not legally binding, but provide an important basis for international agreement on the environment.

Soipan Tuya, Kenya's cabinet secretary for environment, climate change and forestry, said at a time when meeting SDGs has become challenging as many countries in Africa are still grappling with poverty and economic inequality increasing globally, the international society should demonstrate solidarity in this year's UNEA session for concrete results.

"The world will be looking to us here in Nairobi this week to renew hope. And hope we must provide as we consider the draft resolutions," she said.

"A lot of action, hard work, honest negotiations and leadership are therefore needed over the next week if this UNEA is to live to its promise."

Zainab Hawa Bangura, UN under-secretary-general and director-general of the United Nations Office at Nairobi, said concrete actions are needed for the international community to deliver on the goals already agreed.

"In tackling the triple planetary crisis of climate change, nature and biodiversity loss, and of pollution and waste, there is only one way to deliver — action, action, action!" she said.

Bacha Debele Buta, Ethiopia's permanent representative to the UNEP, said Africa is severely impacted by environmental challenges such as climate change, land degradation and pollution, and called for more international assistance to help its sustainable development.