Everything that one associates with the name Michael Bloomberg is larger than life. His skyscraper on Lexington Avenue is one of New York's tallest. His career, which saw him morph from engineer to investment banker to mogul with his own media and data company. Personal wealth that has been estimated at around $50 billion. And then, of course, there's the political career: He served as New York mayor from 2002 to 2013, as a United Nations special envoy for cities and climate change, as a man who has donated billions to health care, the environment and climate protection efforts. He's been a member of both the Democratic and the Republican parties.

The only thing about Michael Bloomberg that isn't outsized, it seems, is the man himself. His dry jokes about his height are frequent and well-rehearsed.

The interview with Bloomberg takes place in his modest office. It's clearly a workspace rather than some flashy CEO spread. Bloomberg is usually on the go, anyway, either flitting about the building or traveling around the world. He wants to talk about his new book, "Climate of Hope," which he wrote together with environmentalist Carl Pope. The subject of Donald Trump, of course, will be unavoidable. Bloomberg has decaffeinated coffee brought to him in a paper cup before starting the talk.

SPIEGEL: Mr. Bloomberg, the whole world was shocked by Donald Trump's decision to withdraw from the Paris Agreement. But you have argued that it doesn't actually matter that much. Why are you so optimistic?

Bloomberg: For sure I would prefer Trump had not withdrawn from the Paris Agreement. But the fight against climate change is really done at the local level -- whether it's cities, local governments or the private sector, corporate and individual. No matter what Trump says, nobody is going to go back and take the scrubber out or change back to polluting. The damage that Trump can do is if there are countries that are on the fence about whether they want to address the issue, this gives the naysayers, the doubters, those that don't want to do anything, a little more ammunition.

SPIEGEL: But can the U.S. still achieve its commitment under the Paris Agreement of reducing emissions by roughly one-quarter by 2025?

Bloomberg: In terms of whether America will meet its goals, I don't think there's any question about that. We've continued progress in the six months since Trump got elected, and the good thing about what we're doing is that success begets success. As we bring down greenhouse gases, for example, we've closed half of the coal-fired power plants in the country in recent years. There's more impetus to try to close the other half because you can see that it is working. So, you know, I had hoped that Trump would not do that, and it doesn't make any sense to me, but regardless, it is not as cataclysmic as it could be.

SPIEGEL: Your foundation has provided $100 million in support to the Beyond Coal campaign, and you also pledged $200 million to your recently launched American Cities Initiative. What is your goal?

Bloomberg: We are funding organizations that help convince the owners of coal-fired power plants that, from an economic point of view, they'd be better off with natural gas or renewables -- also from a PR point of view. We continue to have campaigns to try to convince people to paint their roofs white or have green roofs or to switch from incandescent to LED (lighting). I mean, in the end, capitalism is a wonderful thing. It really does drive people to do what's in their own interest. And that is often good with regard to climate change.

SPIEGEL: How much money would you be willing to spend to stop climate change?

Bloomberg: You tell me what it takes.

SPIEGEL: So you would pay what it takes?

Bloomberg: Well, let me rephrase that. We've given close to a billion dollars to fight smoking. We've given close to $2 billion to Johns Hopkins University in Baltimore, a lot of it for its School of Public Health. We've shown that you can use the money intelligently and make a difference, and we will continue to do that.

SPIEGEL: You argue that it is the cities and not the federal government that play the key role in working to stop climate change. What brings you to that conclusion?

Bloomberg: Fifty percent of the world's population lives in cities. In a couple of decades, 70 percent of the world's population will be living in cities. Cities are where the problem is. Cities are where the solution is, where creativity exists to address the challenges and where they have most impact. This is why, in 2005, the C40 was founded, an organization of cities that address climate change. It started with 18 cities; now it's 91. Cities simply are the key to saving the planet.

SPIEGEL: So, you're saying that what the Trump administration decides in terms of climate change is irrelevant?

Bloomberg: Yes, and I never thought that it was the job of the federal or state level anyway. You know, it would help. I'd love to have a president who really was out there leading and traveling around the world campaigning for joint climate change action. Even the Chinese government is trying to get people to stop polluting. And I think the federal government level in China is acting more responsibly than the American government.

SPIEGEL: On the other hand, the Trump administration is currently rolling back a lot of regulations that aim to protect the environment and climate. Doesn't that endanger the goal of reducing emissions?

Bloomberg: Generally speaking, I think no matter what the Trump administration does, companies are not going to go and say, "Oh, tally ho. Let's put pollutants in the air.

SPIEGEL: What about Republican-governed states like Texas, in which many emissions are being generated through the production of oil and gas?

Bloomberg: The governor of Texas was a real climate change, well, "skeptic" would be a nice way of phrasing it. Still, though, Texas is a leader in renewables. So, what I care about is what they are actually doing, not what they are saying.

SPIEGEL: What drove you to become a climate change activist?

Bloomberg: I became interested in public health when I was chairman of the board of Johns Hopkins University. I started thinking, you know, it makes more sense to prevent than to cure. Other ways of looking at the environmental or climate change stuff is to frame it in the context that it is simultaneously a public health issue. One out of eight premature deaths worldwide happens because of air pollution. The worst power plant in America kills 278 people a year and causes 445 heart attacks. So, when we improve air quality we improve our lives, and at the same time we improve the climate as well. We must see climate policy from this perspective and not as an abstract threat that may threaten our survival in 100 years.

SPIEGEL: Why are people so obviously voting against their own interests? Why don't they recognize that protecting the climate protects them as well?

Bloomberg: People do that all the time. But when you do the polling in the U.S., it has gone from less than 50 percent who thought climate change was real to 70-odd percent. And if you listen to the Republicans in Congress, they used to say, "Oh, climate change doesn't exist." Then they switched to "Well, it exists, but it's not man-made," to "Well, I'm going to address the issue." Why? Because when they go home, the local constituent says, "Wait a second. What are you talking about? We just had a flood. We haven't had rain in a long time." They can't get away from it.

SPIEGEL: Still, within the Republican Party, there continue to be a lot of climate change deniers. Is that why you left the party?

Bloomberg: It had nothing to do with it. I at one point thought that I was going to run for president of the United States as an independent. I became a Republican because the Democrats wouldn't let me on the ballot for mayor of New York, but I'm not a partisan person. So, I left the party again.

SPIEGEL: You thought about running in 2016 as an independent candidate, but decided against it. Do you regret that you didn't?

Bloomberg: No. We convinced ourselves, I think fully, that an independent can't win in this country. The Constitution is structured for basically a two-party government, a two-party race.

SPIEGEL: Do you see Trump as a danger to American democracy?

Bloomberg: I hope not. I gave a speech at the Democratic National Convention in 2016 and warned of Trump. America has survived for almost 250 years with its imperfect democracy, but, you know, maybe it's a better democracy than elsewhere. And I am sure American democracy will survive.

SPIEGEL: One main driver for people to vote for Trump was their resentment of the establishment, the elites. Where is that coming from in your opinion?

Bloomberg: A lot of the Trump voters thought: "The current stuff has not helped me. I want a change." Trump got elected partly because he had a message: "Vote for America." "Make America Great." "America" is a good word. "Great" is a good word. Hillary never came up with a message other than "Vote for me because I'm a woman." I make no secret of the fact that I was not a big Hillary Clinton supporter, but I thought in the two-way race between her and Donald Trump, that she should have been the president. But Trump promised a lot of things. And now he's six months in and hasn't passed a piece of legislation yet. Now, I personally have said we should help him. I didn't vote for him. I didn't think he was the right person. But once we have an election and he gets elected, then we have a responsibility as citizens to help him.

SPIEGEL: To help him? I thought you would have a very different opinion on basically everything?

Bloomberg: Absolutely, I still don't agree with him on most things. I disagree violently with a lot of things, for example regarding the elimination of Obamacare or cutting taxes. We need to have more taxes, not less, and we need the taxes we have, certainly, to provide services -- for defense and education and health care. We should not cut money here in order to cut taxes.

SPIEGEL: So why wouldn't you be happy if he fails with his agenda?

Bloomberg: Because in the end, the message will be: Oh, Trump tried to do what he promised. It was the "liberals" who wouldn't let him. Forget about the fact that it's in the Republican Party that he can't get through the votes. And for sure I'd like to change his views -- for sure I hate a lot of things he does. But I live here. My kids, my grandkids live here. I don't want him to fail. That's sick and not good for my kids. I want Trump to be successful. I don't think he will be, and when he does things that I believe are harmful, I will certainly try hard to stop that. But I don't think that we should do what (the Republican Senator) Mitch McConnell said. When Obama was elected, he said: "We're going to make him a one-term president."