Climate change, migration, artificial intelligence, perspectives on Africa and combating nationalism take centre-stage this year at Art Basel, the world's top contemporary art fair.

The giant annual event in the Swiss border city of Basel, which aims to reflect current trends in the contemporary world, begins with private viewings for wealthy collectors before opening its doors to the public from Thursday to Sunday.

In the monumental works section, a video by the French-Algerian artist Adel Abdessemed shows an approaching burning boat, intended as an allegory of the tragedy awaiting many migrants attempting to cross the Mediterranean Sea.

Close by, Ghanaian artist Serge Attukwei Clottey illustrates the water shortage crisis through a huge installation entitled "Sea Never Dries".

The giant tapestry is made up of fragments of the yellow cooking oil containers found throughout Ghana, which are then reused to collect water.

"Artists are the thermometer of what's happening in the world," said Giovanni Carmine, one of the Art Basel curators, told AFP. The monumental works offer "a mirror on the interests of artists and of the art market", he added.

- 'Apocalyptic' atmosphere -

The fair tackles topical issues such as the rapid growth of artificial intelligence.

An ephemeral work by Croatian artist Tomo Savic-Gecan uses an algorithm that analyses articles relating to Art Basel's art market report. It uses it to affect the locations, durations and intensity of selected lights.

US artist Adam Pendleton questions racism in the United States with a video centred on the statue of Confederate general Robert E. Lee in Virginia's capital Richmond, which came under the spotlight in the wake of the Black Lives Matter movement.

The artist, who hails from Richmond, documents the transformations the statue went through -- being covered in graffiti, sprayed with paint, then finally pulled down to be transferred to the city's Black History Museum -- symbolising the changes in US society.

Some 76 monumental works fill the section devoted to pieces intended for purchase by museums or major art collections.

Carmine acknowledged that "the atmosphere is a bit apocalyptic" -- but with "a touch of hope", he added.

Long underrepresented, African artists are playing an increasing role.

There is a triptych by Kenya's Kaloki Nyamai, and "The African Library" installation by the Nigerian-British artist Yinka Shonibare.

This work is filled with books covered with fabrics bearing the names of Africans who helped shape the continent's identity.

- 'Stupid idea' -

The fair takes over the city for an entire week. Works by renowned artists are dotted throughout Basel, including one by Britain's Martin Creed, who won the country's prestigious Turner Prize for contemporary art in 2001.

Creed has planted a flagpole in front of the historic city hall with a flag simply reading "air".

"A flag that says 'air', to me, is kind of a stupid idea. So I thought I would try it," he told AFP.

"Putting a flag in the earth to say that you own it is a form of nationalism. It's stupid. I think nationalism is stupid. I think flags are stupid. Nobody owns anything. It's completely delusional."

He is amused by those who use his flagpole as simply something to lock their bicycles to.

More than 4,000 artists from 36 countries are represented in 284 galleries, often by their most expensive works.

If recession fears are cooling the art market, the Basel galleries still manage to seal big sales.

The Pace Gallery, one of many galleries presenting and selling work at the fair, has unveiled a new series of sculptures by the US artist Jeff Koons, representing a stainless steel fox inspired by 18th-century European porcelain.

"People are very excited about the fox," said Marc Glimcher, chief executive of the Pace Gallery, which has already sold two versions for $3 million each, including one which is finished but has yet to be painted.

noo/rjm/jj