"The upcoming COP26 is one of the most important meetings in my lifetime and in your lifetime," said Bob Watson, a leading environmental scientist who chairs one of the two governing committees of the new global citizens' assembly.

Watson, also a former chair of the United Nations' Intergovernmental Panel on Climate Change, said the bottom-up initiative would help ensure policymakers are tuned into ordinary people's perspectives.

"Your voices represent the people of the world, and it is vital that governments and the business community hear your concerns - they need to listen to you," he told the online launch of the global assembly.

"They need to hear that we need a more equitable world, and that nobody is left behind. The time for action - not talking - is now," he added.

The assembly's 100 members are being chosen by lottery from around the world and will reflect the global demographic make-up, with 60pc of participants from Asia and 17pc from Africa.

Half will be women and 70pc will earn $10 a day or less, the organisers said.

The initiative - championed by more than 100 climate, community and public policy groups worldwide - is also supported by the United Nations and the British government as the host of the COP26 summit in Glasgow.

The assembly launch comes amid concerns that unequal access to vaccines and high travel costs could exclude officials and activists from developing nations from the COP26 summit, further side-lining those who are already vulnerable to climate change.

Those concerns prompted a call by a network of 1,500 groups last month to delay the Glasgow conference, but the British government has insisted the summit - already postponed a year due to the COVID-19 pandemic - should not be put off again.

Alok Sharma, the senior British official who will preside over the COP26 talks, said the global assembly was "a fantastic initiative".

"We recognise just how important its work is and also because we are committed to bringing the voice of global citizens into the heart of COP26," he told the online launch.

The people's assembly will deliberate on how climate change can be addressed in fair and effective ways and will present its members' views on the sidelines of the COP26 talks.

Its recommendations will be finalised in March next year and delivered in a report for distribution to world leaders. Organisers are also working to encourage civil society groups in different countries to hold "community assemblies" to broaden discussions on how climate change is affecting the local level.

The COP26 conference has been billed as the last chance to galvanise the collective effort needed to limit global warming to 1.5 degrees Celsius above pre-industrial times.

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