The deep rainforests of the central Amazon and the scorching sands of the Mojave desert have long been recognised as of outstanding natural importance by the United Nations. Now, an altogether more unlikely ecosystem wants to join their ranks. Brighton and Hove, famous for its kiss-me-quick pier and hedonistic nightclub scene, is bidding to become the world's first city to be a Unesco "biosphere reserve".
The city council will launch its attempt at achieving the designation later this month, when it will map out a way to join places of natural splendour as diverse as the Cape Winelands in South Africa, Mount Olympus in Greece and the icy wastes of north-east Greenland on Unesco's register.
It believes the Sussex city's network of nature reserves on the fringes of the South Downs, rapidly growing local food production and low-carbon housing schemes could qualify it for a status which is also being sought by environmentalists in Rome, Seoul, Stockholm and Cape Town.
"Since 2007, over half the world's populations have lived in cities," said Denise Cobb, the deputy leader of the council. "So making cities less environmentally harmful - or even beneficial - is one of our most pressing needs."
She wants Brighton to "lead the way on sustainable cities and hopefully make us the UK's first urban biosphere reserve".
That ambition has astonished some locals, who point to the city's heavy traffic congestion, and its residents' hefty ecological footprint is the fourth worst of 60 British cities measured by the conservation organisation WWF. Opposition politicians from the Green party have accused the Conservative administration of "spin" and remaining "in the dark ages" on the environment after its planning committee refused applications for domestic solar panels.
"The aspiration to become the UK's first urban biosphere city is fantastic," said Keith Taylor, convener of the Green party, which has 12 councillors. "But we have a history in this city of chasing titles. I wonder whether we actually need to be called an urban biosphere city when actually what's really wanted is action."
Unesco has decided to accept bids from cities for biosphere reserve status to try to "update the image of cities as hotbeds of pollution, stress, poverty and crime".
"Cities are havens of natural and cultural diversity and may hold the key to sustainable development in the 21st century," the Paris-based organisation said in a statement.
Unesco's advisers said the criteria were likely to demand that ecology interweave seamlessly with urban life. There should be nature reserves but also buildings with green roofs and "green walls" hung with plants to encourage wildlife, clean waterways and a commitment to low-carbon housing.
"These places will not be pristine biospheres like the Amazon, but in many of our cities there are areas of biodiversity and it's about identifying them and making sure they are given elevated status and thoughtfully managed," said Matthew Frith, a member of Unesco's UK working group on urban biospheres.
Brighton already has several nature reserves, including Stanmer Park, where there are community apple orchards, acres of allotments and an "earthship" - a low-carbon demonstration home with old car tyres for walls.
One Brighton, an apartment complex under construction in the centre of the city, will have allotments on the roof and will be powered entirely by renewable energy. Other ecohome developments have sprung up, including Hog's Edge, a row of green-roofed, timber-frame houses near the Bevendean nature reserve.
The shops in the North Laine in the city centre testify to the growing eco-culture among Brighton residents. Cuttlefish Organic Hairdressing is just along from Vegetarian Shoes, and beside the train station is the Brighton Peace and Environment Centre, offering "education for a fairer, greener world". Next door, Arka offers eco-friendly funerals.
In contrast with the WWF assessment, Brighton was last year labelled the UK's most sustainable city by Forum for the Future, a charity founded by the environmentalist Jonathon Porritt.
The calculation included quality of life and how well the city is preparing for a sustainable future as well as current carbon footprint.
But it may not be enough.
"The carbon footprint of Brighton and Hove is one of the highest in the country, quite simply because it is an affluent region," said Bryn Thomas, who runs the Brighton Permaculture Trust, which looks after the orchards at Stanmer. "There's higher car ownership, more international air travel, people are more likely to buy beans flown in from Kenya in Brighton and Hove than in the valleys of Wales, where carbon footprints are smaller."
"I think it's rubbish," said John Freeman, a 69-year-old engineer taking a walk on Brighton Pier. "Having been to the [Cape] winelands and various other places, I don't think you can compare this old concrete jungle with that, to be honest, even with the sea and the marine life and the sewage that is discharging in here - there's no chance."
"I've been to the Amazon and it was beautiful; you can't put Brighton in the same category," said Myra Morgan, 62. "This is lovely and it should be preserved, but not put on any register."