This article is part of our special section on the DealBook Summit that included business and policy leaders from around the world.

“There’s always tough stuff going on, wars and depressions and recessions,” Jamie Dimon, chief executive of J.P. Morgan Chase, told me. But this time, he said, it may be different — it may be worse.

“It’s dangerous,” he said, shedding his steely confidence for a moment, at the DealBook Summit last week in New York.

Business, policy and cultural leaders have always had to contend with uncertainty, a watchword that has almost become a cliché.

However, today, it appears that uncertainty isn’t just an excuse for less-than-expected results. It is a palpable feeling that seems to be affecting virtually every major figure at the top of the leadership complex across the world. Leaders are taught to always display optimism and confidence, but right now, they are feeling a vulnerability that has often been foreign to them.

That was the lesson that emerged from interviews with some of the most consequential leaders in their fields in the world.

Vice President Kamala Harris talked with deep fervor about democracy being at risk; Elon Musk of X, Tesla and SpaceX, spoke of the existential threats to the planet (as well as offering some choice words — that went viral — for advertisers that dropped his social media platform); Bob Iger, chief executive of Disney, discussed how the movie business may be forever disrupted; Nvidia’s founder, Jensen Huang spoke at length about the A.I. revolution that will affect every corner of computing — and society.

The president of Taiwan, Tsai Ing-wen, expressed her fears that China is seeking to manipulate the country’s elections; and the president of Israel, Isaac Herzog, discussed how the attack by Hamas on Oct. 7 and the war that has followed has upended the Middle East, geopolitics more broadly and the discourse around the world.

It is hard to know how to measure the current level of uncertainty and disruption — or how to react to it. But it is clearly here. Some leaders power through and hope for the best, some plan for the worst and others try to remain optimistic. If history offers any lesson, it is that those who keep their wits about them during these periods have the most success.

“My view is when you have this kind of risk, you better deal with it very seriously because the chance of something going wrong is high,” Mr. Dimon said. “And if it goes wrong, the cost would be enormous.”

The uncertainty may be even greater in China, which was just downgraded by Moody’s this week. President Tsai of Taiwan, in her first major interview with a Western news organization in years, suggested, that “the Chinese leadership at this juncture is overwhelmed” and “my thought is that perhaps this is not a time for them to consider a major invasion of Taiwan.”

Still, she allowed that “China, of course, is anxious, interfering in Taiwan’s election” and “they are indeed trying to sway an election in their favor.” She added that China does this through “the use of military threats and economic coercion.”

War and the prospect of war is one kind of uncertainty. But it often feels like industry is going through its own struggles, with an intensity that is far greater than in the past.

“The disruption to this business right now is harder and faster than we ever imagined,” said David Zaslav, the chief executive of Warner Bros. Discovery. “We had to make a lot of very difficult decisions, and we had to move a lot faster than we probably wanted to because this is a generational disruption.”

Mr. Zaslav, commenting on his decisions to lay off staff and shutter productions, said that the situation took him by surprise a year after the two media companies merged.

“As the first year ended, we really thought we were getting close to the shore and we were getting there,” he said. “But this disruption, this idea of people consuming content on TikTok going to different streaming services, it’s a generational disruption.” And then he raised the prospect that artificial intelligence will once again rewrite the business models of his and many other businesses. “It’s an existential moment. What is the impact of A.I.?”

Mr. Iger suggested that Disney was seeing many of the same challenges. “I think the movie business is changing,” he said. “Actually, the box office today is about 75 percent of what it was pre-Covid. I think we have conditioned the audience to expect that these films will be on streaming platforms relatively quickly and that the experience of accessing them and watching them in the home is better than it ever was.”

In other words, the Hollywood studios have disrupted themselves.

And dozens of other industries are about to be upended by a remaking of computing.

“Every aspect of the computer has fundamentally changed,” Mr. Huang said. “Everything from networking to the switching to the way the computers are designed to the chips. And so all of the software that sits on top of it and the methodology that pulls it all together, it’s a big deal because it’s a complete reinvention of the computer industry.”

That will inevitably create opportunity and a new set of winners, but also losers. And as business gets more digital and consolidates, it is increasingly becoming a winner-take-all economy.

But for all the hand-wringing, Mr. Musk left us thinking about the future in new ways.

“If we are a single-planet civilization, then we are simply waiting around for some extinction events,” he said. “If you’re a multi-planet civilization, you’ll live much longer,” he said, adding that it would also serve as a steppingstone “to being out there among the stars.”

This is not simply a defensive motivation, Mr. Musk continued, but it is also one that gives meaning to our lives — especially at a time when uncertainty can often feel like despair.

“You know, there have to be reasons when you wake up in the morning and you’re happy to be alive. You have to say why are you excited about the future or what gives you hope? And if you’re unsure, ask your kids.

“I think the idea of us being a space-faring civilization and being out there among the stars is incredibly inspiring and exciting and something to look forward to. And there needs to be such things in the world.”