The greater number of officers appears to be a direct response to threats by the Islamic State terrorist organization to carry out attacks at high profile locations in the U.S. The annual gathering of more than 130 heads of state in New York is basically as high profile as it gets.
Add to that the fact that President Barack Obama organized a series of military air attacks against the Islamic State and Khorasan, another terrorist organization based in the Middle East, and it's apparent that the security presence in and around the United Nations is there for good reason.
However, as one local woman who works in an office that's inside the U.N. security perimeter pointed out, the serious security may not be all that serious.
"I feel safe," said Kenya Camacho, "but at the same time, I think that just showing my picture I.D. doesn't tell the officer anything. They didn't search my bag."
The second global issue with a big local impact, climate change, was introduced by Mayor Bill de Blasio himself. He was the first speaker at the U.N. Climate Summit, the event at U.N. Headquarters that precedes the General Assembly meeting.
At the summit, world leaders, including Pres. Obama, gathered to discuss actions needed to be carried out in order to halt climate change. Both the president and the mayor mentioned the hundreds of thousands of climate change protesters who demonstrated in New York last Sunday, along with millions of more people worldwide.
"Our citizens keep marching," Pres. Obama said. "We cannot pretend we do not hear them."
The president pointed out that the U.S. has tripled its wind energy generation, and increased its solar power generation ten-fold in the last eight years. Much more must be done, he said. An example of the kind of action of which Pres. Obama spoke came from Mayor de Blasio.
"New York City is firmly committed to 80 percent reduction of greenhouse gas emissions by 2050," the mayor said from the General Assembly Building podium.
That translates into retrofitting city buildings, and privately owned buildings and houses at an estimated cost of $1 billion over a decade.
The energy savings is projected to far outpace that, and the conversion of heating and cooling systems is expected to create jobs. Still, it may be a sacrifice, at least at first.
"If it's for the betterment of the environment," New Yorker Damon Bryan told PIX11 News, "then it's okay."
Not everyone agrees. But the density of New York, and the close proximity of world leaders -- over 130 of them -- is a way to make progress on the issue for the leaders who believe changes must be made to combat climate change.
"Just a few minutes ago, I met with Chinese Vice Premier Ziang Gaoli," Pres. Obama said from the podium. The presence of so many leaders in one location allows for quick encounters that can result in action. In the case of the president and the Chinese vice premier, they agreed face to face on mutual emission reductions.
One final way in which the global issue of climate change has a New York impact was pointed out by Mayor de Blasio from the General Assembly Building podium. He said that the groundwork for the emission reductions that his administration intends to carry out was laid by the current U.N. special envoy on climate change, Michael Bloomberg.
Bloomberg's emission reduction plans were adopted prior to his assuming his current special envoy title.