Manhattan was busy last week, given the string of events held to coincide with the UN General Assembly. But over on Wall Street, the exuberant traders should perhaps give pause for thought about worries raised by Michael Bloomberg.

NEW York doesn’t allow itself any time for the post-summer blues. September in most big cities is a time of reflection and regret: Reflection on the languors of summer, regret that we all have to go back to normal life — the children back to school, the adults back to work.

New York, on the other hand, welcomes the world to an end-of-summer party called the UN General Assembly (UNGA). Already one of the most cosmopolitan of metropolises, in September New York flings open its doors to every nation on earth, with all the entourages, cavalcades and plain hangers-on that the diplomatic world attracts around it. It is an exciting, but fraught time. Here are five things that I learned from UNGA week in Manhattan.

1. Having the president of the United States (POTUS) live on the doorstep of the UN area is completely impractical. When the extra security laid on for the visiting diplomats at the UN building by the East River on 42nd Street is added to the lockdown around the president’s base at Trump Tower on 56th, a huge chunk of Midtown effectively becomes a no-go area, cutting Manhattan in half. Fifth avenue was closed for most of the week as armies of NYPD officers sought to keep protesters and even sightseers away from the tower. Getting to the swanky Plaza Hotel on the corner of Fifth Avenue and Central Park — venue for the big events that are deliberately chosen to coincide with the UNGA — was a nightmare. The knock-on congestion in the rest of the city meant that the subway was the only reliable way of getting around. The city’s rail network is already creaking, and during UNGA it can barely cope.

2. Climate change has become the top priority among the business elite that descended on the city. Maybe the unique concurrence of hurricanes, forest fires and earthquakes focused business minds on the environment, maybe it was a way of expressing opposition to a president who does not seem to believe in it, but policymakers, chief executives and civil-society leaders appeared to be unanimous in their conviction that climate change has to be confronted across the world. One of the most eloquent was Gov. Jerry Brown of California, who related the current state of civilization to that of the classical world. “The great civilizations of Greece and Rome collapsed because they could not solve their problems. We don’t want to the do the same,” he said.

3. A related theme — sustainability — is becoming a new financial specialism. As the UN recommitted itself to its sustainability development goals (though the US president failed to mention them) and the World Economic Forum pledged the efforts of its members and followers toword achieving sustainable economic growth, the financiers seemed to wake up to the business potential behind the new development strategy. Perhaps Arif Naqvi, founder of the Middle East’s biggest private equity group Abraaj, expressed it in perfect financial terms when he pointed out that the default rate on US infrastructure projects is 8 percent, while that on African projects is 1 percent. When sustainability and finance align, it all begins to make good sense.

4. Remaining on the financial theme, the beating heart of global capitalism — Wall Street — appeared to be in rude health. A trip to the New York Stock Exchange coincided with the bell-ringing ceremony for an Argentine online travel agency, Despegar, which raised $332 million, and came a day after a similar ceremony for Best Inc., a Chinese logistics company, which raised $450 million. Both opened to healthy first-day premiums, which was not difficult given the state of the market. As I was chatting to a market maker on the floor, the screens lit up with the headline “Dow Jones hits new all-time high”. The trader said nonchalantly: “That’s old news. We see it every day now.” The financial district was handling all the exuberance far more casually than the Trump/ UNGA show up town. The biggest excitement out on the street was the line of female tourists waiting to be photographed touching parts of the famous “Charging Bull” statue on nearby Broadway. Foreigners are very welcome on Wall Street, it seems.

5. Michael Bloomberg is worried. The indefatigable 75-year-old founder of the eponymous news and information organization seemed to be everywhere in the city where he once was mayor. He appeared at a Saudi Arabia-sponsored MiSK event, at the UNGA, at the WEF summit and of course at his own global business forum. He somehow found time to be interviewed on CBS News where he was asked why the financial indices keep on rising. “I cannot for the life of me understand why the market keeps going up,” he answered, before reeling off a list of reasons — infrastructure failings, creeping technology, immigration controls — why they should be going into reverse. When Bloomberg is worried, we should all be — even in exuberant New York.

Frank Kane is an award-winning business journalist based in Dubai. He can be reached on Twitter @frankkanedubai

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