The stunts Thursday drew the attention of hundreds of onlookers, along with TV cameras that captured the drama in real time. Crowds on the street pressed against police barricades to watch the climb, and people clapped and cheered for him while snapping pictures on their cell phones.
"Only in New York. This is why I live in New York," said 29-year-old Emily Perschetz, who watched the second climber for about 20 minutes.
The first man, French stuntman Alain Robert, unfurled a banner as he climbed that said "Global warming kills more people than a 9/11 every week."
He was promptly arrested by the NYPD when he made it to the top, charged with reckless endangerment and released on bail early Friday.
Hours later, a Brooklyn man, Renaldo Clarke, made his own ascent up the building, saying that he wanted to promote awareness about malaria.
He, too, was arrested on charges of reckless endangerment when he reached the top and was awaiting arraignment. Neither man wore a rope or harness.
At moments during his ascent, Clarke appeared to slow and tire.
Police said the officers became concerned that the man might be an emotionally disturbed copycat, and he was taken to a hospital for a psychiatric evaluation before being returned to police custody.
Robert's Web site says he has climbed more than 70 skyscrapers around the world including the Eiffel Tower and Louvre Pyramid in Paris. He was arrested in February after climbing a 42-floor building in Sao Paulo, Brazil.
The stunts were staged at the Times building, just a block south of the busy intersection of Eighth Avenue and 42nd Street, across the street from the Port Authority bus terminal.
A spokeswoman for the Times, Catherine Mathis, criticized the climbers, saying the newspaper was "taking steps to prevent future occurrences."
"Their illegal and ill-considered actions jeopardized their safety and the safety of others," Mathis said in a statement.
Earlier, she said that no one at the newspaper knew of Robert's plan in advance.
Reacting to the content of Robert's banner, Mathis noted that the Times itself has "a very green building."
She said the ceramic slats save energy by reducing the amount of heat and light entering the building, where the Times moved last year.
Robert's Web site says he climbs even though he suffers from vertigo and is "60 percent disabled" from previous accidents. It also says he has been jailed many times but it does not matter because he "would rather stay in a prison than in a hospital."
The second climber wore a T-shirt with the words "Malaria No More," the name of an organization which promotes awareness about malaria and raises money for bed nets. Martin Edlund, a spokesman for the organization, said the climber was not affiliated with the group.
Clarke's Facebook page says he enjoys climbing and lists "xtreme living" among his interests. The page identifies him as an information technology support manager for a Manhattan advertising agency. He did not immediately return an online message.
A Facebook friend, Catherine Zubkow, said Clarke is a seasoned climber and is not emotionally disturbed.
"He would never intentionally try to harm anyone," she said via e-mail. "It is possible he did not foresee all the consequences of his actions with regards to the law."
Some city officials and bystanders took a dim view of the climbs.
"Regardless of the cause, in this day and age the police department has more important things to worry about than ridiculous stunts like this that endanger the police and public," Councilman Peter Vallone Jr. said.
Construction worker Alfonso Murphy, who works at a site next to the Times building, said he didn't care what cause the climbers were trying to draw attention to - the stunts were dangerous. "He could have been climbing for gas prices or foreclosures," Murphy said of Robert.
New York's skyscrapers have long attracted high-rise stunts.
The host of a cable TV show called "Stunt Junkies" was arrested in 2006 as he tried to parachute from an Empire State Building observation deck. Police and security guards seized him and handcuffed him to the 86th-floor security fence as he climbed over it.
And in 1974, French artist Philippe Petit made a daring and illegal wire-walk between the twin towers of the World Trade Center. British director James Marsh made "Man on Wire," a retelling of the derring-do.
