RIO DE JANEIRO -- With fireworks forming the word "Rio" in the sky and supermodel Gisele Bundchen shimmering to the tune of "The Girl From Ipanema," Rio de Janiero welcomed the world to the first Olympic Games in South America with a serious message underlying the celebration: Let's take care of our planet.

After one of the roughest rides ever from vote to games by an Olympic host, the city of beaches, carnival, grinding poverty and sun-kissed wealth opened the two-week games of the 31st Olympiad with a high-energy gala celebration of Brazil's can-do spirit, biodiversity and melting pot history.

The low-tech, cut-price opening ceremony, a moment of levity for a nation beset by economic and political woes, featured performers as slaves laboring with backs bent, gravity-defying climbers hanging from the ledges of buildings in Brazil's teeming megacities and -- of course -- dancers, all hips and wobble, grooving to thumping funk and sultry samba.

Brazil also packaged its party with solemnity, lacing the fun and frivolous show with sobering messages about global warming.

Images of carbon dioxide, a greenhouse gas, swirling in the Earth's atmosphere were followed by projections of world cities and regions -- Amsterdam, Florida, Shanghai, Dubai -- being swamped by rising seas. The peace symbol, tweaked into the shape of a tree, was projected onto the floor of the Maracana Stadium that filled with thousands of athletes from 207 teams.

"The heat is melting the ice cap," a voice intoned. "It's disappearing very quickly."

The crowd roared when Bundchen, the Brazilian supermodel and wife of New England Patriots quarterback Tom Brady, sashayed from one side of the 78,000-seat Maracana Stadium to the other as Tom Jobim's grandson, Daniel, played his grandfather's famous song about the Ipanema girl "tall and tan and young and lovely."

Brazilian marathoner Vanderlei Cordeiro de Lima lit the cauldron to cap the ceremony.

After Brazil's most famous athlete -- soccer star Pele -- said he will not appear, the Olympic mystery of who might light the cauldron had remained intact. The cauldron was designed by American sculptor Anthony Howe, who told The Associated Press he was inspired by life in the tropics. There are two cauldrons in Rio, one at the Maracana and another open to the public in downtown Rio.

In a video preceding the show, U.N. Secretary-General Ban Ki-moon said the games "celebrate the best of humanity" and appealed for an Olympic truce by calling on "all warring parties to lay down their weapons" during the two weeks of sporting achievement.

There were times after the International Olympic Committee selected Rio ahead of Chicago, Tokyo and Madrid in 2009 when it seemed that the city of 6.5 million people might not get its act together for the world's greatest sporting mega-event.

The spreading health crisis of the mosquito-born Zika virus kept some athletes away. Promises to clean Rio's filthy waters remained unfulfilled. The heavy bill for the games, at least $12 billion, made them unpopular with many. Heavily armed security stopped a small group of protesters from getting close to the stadium ahead of the ceremony.

But with more than a dash of "gambiarra," the Brazilian art of quick-fixes and making do, Rio is ready.

The honor of declaring the games open will fall to Michel Temer, Brazil's unpopular interim president, standing in for suspended President Dilma Rousseff. Her ouster less than four months out from the games for alleged budget violations was one of the many complications that roiled Brazil's Olympic preparations and impacted the opening ceremony itself.

Fewer than 25 foreign heads of state were expected, with others seemingly staying away to avoid giving the impression of taking sides amid Brazil's leadership uncertainty. As Brazilian officials took their seats in the stadium, there were shouts of "out with Temer" from sections of the crowd.

Jamaica's Usain Bolt, the two-time defending champion in the Olympic 100- and 200-meter races, skipped the ceremony, as expected. Bolt announced his decision earlier in the day. Friday was the fourth anniversary of Bolt's winning the gold in the 100 at the London Games.

Greece, the historical and spiritual home of the games, led the march of athletes into the stadium. They were being joined by the first Refugee Olympic Team of 10 athletes displaced from Syria, South Sudan, Congo and Ethiopia. Their flag-bearer, Rose Nathike Lokonyen, fled war in South Sudan and ran her first race in a refugee camp in northern Kenya.

With "USA" emblazoned on the back of his jacket, Michael Phelps carried the flag for the U.S. team, the largest with 549 competitors. At his fifth and last Olympics, it was the first time the record-holder of 22 medals had marched in an opening ceremony, having skipped previous ones to save energy for competition.

On behalf of all 11,288 competitors (6,182 men; 5,106 women), a Brazilian athlete pledged an oath to not take banned drugs -- a promise likely to ring false to many fans after the scandal of government-orchestrated cheating in Russia. Although it escaped a blanket ban, Russia is paying the price in the shape of a smaller team, whittled down from a 389 athletes to around 270.

Iran picked a woman, archer Zahra Nemati, as flag-bearer for its team made up overwhelmingly of men. Another woman pushed Nemati's wheelchair. She was paralyzed in a car accident as a teenager.

After the grandeur of Beijing's opening ceremony in 2008 and the high-tech, cheeky inventiveness of London's in 2012, Rio's was earthier and less swish but more sobering, with its gloomy environmental look at the future and deliberate penny-pinching. Creative director Fernando Meirelles said the budget, slashed by half as Brazil's economic recession bit ever harder, "is 12 times less than London, 20 times less than Beijing."

"It is pretty tacky to be overspending," he said. "It is not a good message for the world. When 40 percent of the homes in Brazil have no sanitation, you can't really be spending a billion reals for a show. In the end, I feel good that I am not spending money that Brazil hasn't got."