As politicians meet to discuss how to cut carbon emissions, descendants of Southern Africa's first inhabitants are raising concerns about an oil and gas exploration project. Religious leaders have also spoken out, with one saying the project is a sin, and calling on COP27 delegates to curtail the activities of fossil fuel companies.
In the Southern African country of Botswana lies one of the largest inland deltas in the world, a landscape the UN has called "exceptional" and "rare" in its beauty.
The Okavango Delta is an oasis in the heart of the Kalahari Desert. Its waterways and floodplains are home to some of the world's most endangered species of large mammals, like black rhinos. The plants, birds, fish, and animals that live here make up a particularly delicate ecosystem.
It's so precious it has been designated a World Heritage Site.
But there are fears it is under threat, because of fossil fuels.
A Canadian company, Reconnaissance Energy Africa (ReconAfrica), believes there could be a wealth of oil and gas under the ground in the north of Botswana and neighbouring Namibia.
It holds exploration licences for a 34,325sq km area straddling the border of the two countries.
Three test wells have already been drilled in Namibia.
"The project is a sin, and a serious one," the recently retired former Anglican Bishop of Namibia tells me.
Luke Pato spent the last months of his time in Namibia campaigning against the project with a group of other religious leaders. As we sit in the garden of his home in Johannesburg, he tells me why.
"Jesus said, 'I have come so that they may have life and have it abundantly.' He would never be on the side of anything that has the potential to destroy life, to destroy the environment in which people live. I have no doubt that Jesus would find a way of pulling the carpet under the feet of those who are still wanting to engage in the exploration of fossil fuels.
"I would like drilling to stop, this company to pick up its machines and go."
Bishop Pato is worried about the effect that the drilling in Namibia may have on underground water reservoirs that connect to the Okavango River. The river runs along Namibia's border north of the drilling sites, carrying water to the delta in neighbouring Botswana.
ReconaAfrica says its exploration poses no pollution risk.
Mwanyengwa Shapwanale, head of communications for ReconAfrica's Namibian subsidiary says the company is working with Namibia's government "to make sure that not only are we in line with what is expected from us to protect the environment, especially the water, but also to make sure that we go the extra mile."
But Bishop Pato also has another concern: he thinks the exploration of African natural resources by a Canadian owned company amounts to a "new wave of colonialism''. He wants delegates at COP27 in Egypt to put forward "a resolution that would tell companies that are drilling outside of their own countries not to do so".
Namibia's government rejected his criticism, telling the BBC it had a responsibility to develop the country's natural resources for the benefit of its people.
"Reneging on that responsibility will be reckless, therefore as a sovereign democratic country, Namibia will sustainably explore and develop its natural resources," it said.
It pointed out that Namibia's greenhouse gas emissions were "insignificant compared to that of the developed nations". Africa as a whole is responsible for less than 4% of the world's greenhouse emissions.
The issue of whether African countries should continue to exploit fossil fuels is emerging as a point of division at this year's COP. A number say they should be free to exploit oil and gas deposits, in order to grow their economies and end energy poverty.
But Bishop Pato remains unconvinced.
"When there are potential cleaner sources of energy, why take a step back to fossil fuels?" he asks.
In Botswana those concerns are echoed by descendants of Southern Africa's first inhabitants: the San.
For millennia San communities inhabited what is now Southern Africa, living a hunter-gatherer lifestyle. Now there are thought to be around 90,000 left, concentrated in Botswana, Namibia, South Africa and Zambia.
Key to their culture and belief systems is living in harmony with nature. San spirituality is inextricably linked to their relationship with the land, plants, and animals.
"We don't want this project to happen," says Diphetogo Anita Lekgowa, a San activist from Botswana who is attending COP27 in Egypt as a campaigner for indigenous people's rights.
"We are concerned for the environment and the protection of our natural resources, because once [drilling starts] there will be a whole load of change. The animals will migrate, and we fear losing our indigenous plants."
Botswana's government declined several requests for interview, but the Minister of Mineral Resources, Lefoko Moagi, has previously stated that "the terms of the licence require ReconAfrica to preserve in as far as is possible the natural environment [and] minimise… damage to natural and biological resources."
The government has also underlined that no drilling is currently planned in Botswana - the exploration will be carried out by non-invasive means.
But Diphetogo Anita Lekgowa fears that if the presence of oil or gas is confirmed, drilling will eventually take place. Much like Bishop Pato she is worried about what that might bring.
She is from the River San people, who believe the river that feeds the Okavango Delta was given to them by the gods, because it never dries.
Growing up in the village of Khwai on the edge of the delta, the reverence her elders had for the river was woven into the fabric of their lives, she says.
"Our parents would go to the river to dance, connecting with the gods, thanking the gods. Our culture, our way of life, our spirit connects with the river."
If the river and Delta were harmed, Anita says, it "would destroy people emotionally".
"Why is our government interested in oil when there are other things that can be done that can bring in revenue?"
The mountains of the gods
On the other side of the delta, in Botswana's north-west, lies another World Heritage Site - a series of large rock formations so holy to the San that they are known as "the mountains of the gods".
The Tsodilo Hills are where the San believe the spirits of the ancestors reside, and it is through them that they connect with the Most High Being. The hills contain more than 4,500 rock paintings, some of which are thought to be more than 20,000 years old, detailing the history of the San people
San activist Gakemotho Wallican Satau, who lives in the town of Shakawe, to the north of the hills, tells me that for the San the hills are "similar to Mecca for the Muslim people".
Exploration is not allowed within a 20km buffer zone around the hills, but this has done little to allay Gakemotho Wallican Satau's fears. "How could I not worry?" he says.
He particularly fears "tremors or earthquakes" that could lead to the destruction of the paintings.
Across Southern Africa there are San people who argue that their communities have been dispossessed of their land.
"We are already marginalised, we are poor, we have lost land, and now the Canadians are coming," Gakemotho Wallican Satau says.
ReconAfrica's Ms Shapwanale stresses that the project is in its early stages in Botswana, and the company is keen to hear from affected communities.
"We will continuously listen to the San community, we will continuously put in effort and go above and beyond to make sure that they're consulted.
"We listen to them. And we hear, and we get advice on what is the right way to do things."
But, she says, other nations have been trusted to explore for oil and gas, and it helped them to develop their economies.
"If the Namibian and the Botswana governments invite us, I think it's only fair that these two nations should also be allowed to explore the natural resources for the benefit of the people, including the San community."
Additional reporting Jessica Furst