On a rainy day in mid-November, Secretary of State John Kerry stood on the bridge of the USS San Antonio, a state-of-the-art ship designed to deliver up to 800 Marines ashore via helicopters and landing craft. From the bridge, Kerry had a commanding view of Naval Station Norfolk, the largest naval base in the world: aircraft carriers to the left, battleships to the right, a panorama of military power – and one that is rapidly sinking beneath the rising waters of Chesapeake Bay.

As Navy officials told Kerry in an informal briefing aboard the San Antonio, the base was highly vulnerable to sea-level rise. Already, roads connecting the base to the city of Norfolk, Virginia, flood during major rainstorms. At high tide, water surges over the sea walls, threatening key infrastructure and inundating buildings. Kerry, dressed in a sharp blue suit and pink-orange tie, asked the officers about the life expectancy of the base. “Twenty to 50 years,” Capt. J. Pat Rios told him.

There was a slight but perceptible pause among the naval officers and State Department officials on the bridge. It was an extraordinary moment in the annals of American military history: A U.S. naval captain had just told the secretary of state that this strategically important base, home to six aircraft carriers and key to operations in Europe and the Middle East, would be essentially inoperable in as little as 20 years. Yes, they could shore up the sea walls for a while. Yes, they could raise roads. But without the massive influx of billions of dollars to fortify and elevate the city of Norfolk, as well as the roads and railroads that connect it to the surrounding region, the base was doomed.

Kerry asked a few follow-up questions about what was being done now to buy more time, but he hardly seemed perturbed. Part of the reason for that may have been that this daylong tour was a brief diversion from his larger nightmares in Syria and other Middle Eastern countries, which were underscored three days later by the terrorist attacks in Paris that killed 129 people. But a larger part of the reason was that the troubles at the naval base were hardly news to Kerry. He has been talking about the national-security implications of climate change for years. But now, reality is starting to catch up with him. Recent studies have shown that the war in Syria was likely exacerbated by drought and famine. The flood of refugees that is overrunning Europe is offering the world a glimpse of what will happen as the globe heats up. The rapidly thawing Arctic, with its fossil-fuel riches, has become a playground for Russia and China. Nobody has done a better job of adding up what all this means than John Kerry. In fact, in Kerry’s mind, the troubled future of Naval Station Norfolk, the refugee chaos in Europe, the rise of Islamic terrorism and the grinding war in Syria are all accelerated and complicated by our collective failure to take meaningful action to reduce carbon pollution and minimize the impacts of climate change.

As secretary of state, Kerry has accomplished a great deal, including a historic arms deal with Iran. He has also had notable failures, including an attempt to broker a peace deal in the Middle East that fell apart at the last minute. At 72, Kerry has a stamina and appetite for negotiation that are epic. His aides like to point out he has flown nearly 1 million miles since taking office in early 2013. The patrician aloofness that sometimes kept him from connecting with crowds during his 2004 presidential run is not a problem on the diplomatic circuit. “He was born to be secretary of state,” says Heather Zichal, a longtime Kerry aide who went on to become President Obama’s climate and energy adviser during his first term.

In the climate wars, however, Kerry is a forgotten soldier. Al Gore won all the glory (and the ridicule), and President Obama has the muscle. But the truth is, no one has done more in the trenches of this battle than Kerry. He has been in the fight since the first Earth Day, in 1970, and has not let up since, participating in practically every climate conference and U.N. climate meeting in the past 30 years. It helps that he is from an environmentally conscious state like Massachusetts, but his interest in climate change has been anything but politically expedient – he did not shy away from talking about it when he ran for president in 2004, even when pollsters told him it was foolish. He pushed hard for cap-and-trade legislation in Obama’s first term (and, despite Obama’s less-than-full-fledged support, might have gotten it done had not his pal Sen. John McCain, long a supporter of action on climate change, gone MIA on the issue after he lost the 2008 election). As secretary of state, Kerry was one of the prime movers behind last year’s historic U.S.-China deal, in which China agreed to significant carbon reductions and which helped break the bottleneck in U.N. climate negotiations.

After touring the base in Norfolk, Kerry gave a speech at Old Dominion University that tried to sum up the connections between climate change and national security. “The bottom line is that the impacts of climate change can exacerbate resource competition, threaten livelihoods, and increase the risk of instability and conflict, especially in places already undergoing economic, political and social stress,” Kerry said. “And because the world is so extraordinarily interconnected today – economically, technologically, militarily, in every way imaginable – instability anywhere can be a threat to stability everywhere.” Kerry’s audience was not just the several hundred Virginia dignitaries and students gathered at Old Dominion, but also Republicans in Congress who were gearing up to derail the upcoming U.N. climate talks in Paris, which both Kerry and Obama see as an important turning point in the fight against climate change. In effect, Kerry was saying to climate deniers in Congress: If Paris fails, terrorists win.

In Norfolk, Kerry and I talked in the VIP lounge at the base before his tour of the complex, and then again during his flight back to Washington, D.C., on a government-issue refurbished 757, which he shares with other top Obama officials. As we talked, Kerry took his coat off and picked at a bowl of fresh fruit, his voice hoarse after a long day. He looked exhausted, his face more drawn than usual; talking to him, it was hard not to feel the weight of the world. After the terrorist attacks in Paris, we caught up again briefly by phone while he was on his way back from Vienna and Paris.

To most people, climate change is an environmental issue. It’s something that affects trees and frogs and weather. Why should Americans think about climate change as a security issue?

Because it is. Sixteen members on the board of the Center for Naval Analysis, who are all flag officers – generals, admirals, three-star, four-star, retired – have all said this is a major threat multiplier. And there are many different ways in which a security challenge can emerge. You have drought, therefore, perhaps, huge food shortages. Where there is water today, there may not be in the future. That could cause mass migrations. That creates conflict. The water itself – there are wars over water. Already, tribes are fighting in part of the Sahel and other places where water once existed, and now it’s dried up. There’s a history of conflict where resources are finite or scarce.

So if you look around the world, the potential for mass dislocation is rising exponentially right now. We saw massive numbers of people uprooted in Syria and moving into Damascus. The drought in the region did not cause what happened, but it exacerbated what happened. It creates greater instability.

Were the Paris terrorist attacks further evidence of the link between climate change, global instability and terrorism?

Well, it certainly underscores the global nature of Daesh. It’s not directly related to climate change, but it’s part of the web of global interconnectedness – and it shows how one security challenge is a challenge for everybody.

A few months ago, during the Arctic summit in Alaska, you called the refugee crisis in Europe a preview of what’s to come.

Everything is a preview right now, because the course we’re on has created an inevitability to X amount of warming. And we’re already into the mitigation component of our efforts on climate change, which is very scary because we’re behind the curve in terms of what we need to keep it to 2 degrees Celsius, which is the tipping point of allowable warming. And we’re just not making it. And we’re not going to make it in Paris in terms of that, but that’s not the objective. We understand that.

What we will do in Paris, I hope, is gather a head of steam with a message to the marketplace that is significant enough. If 150 nations are taking it seriously and setting targets, even if they don’t make them, that will generate massive investment and a huge amount of private-sector activity. And then you have to hope that somebody comes up with clean-energy technology, which makes it competitive with fossil fuel, and then, boom, you get your low-carbon economy.

What impact did the Paris terrorist attacks have on the momentum for the climate talks?

If they have an impact, it will be that everybody realizes that you gotta get things done, not talk about them. So maybe there will be a little spill-over momentum. But the bigger impact will be on Syria and the counter-Daesh coalition.

In the past, when America’s been faced with major security threats, we’ve mobilized in big ways. Think about what we did to prepare for World War II. With climate, we have done nothing on that scale. Basically, all we’ve done is try to mitigate emissions, and we haven’t even done a very good job of that. If climate change is such a major threat to our security, shouldn’t we be doing far more to combat it?

Well, we’ve done more than mitigate. President Obama has set up his Climate Action Plan. It is not mitigation; it is geared to try to prevent the problem. We have a 26 to 28 percent target for reductions by 2030. We’re looking at 2050 goals now. We’ve upped the requirements on trucks, upped the requirements on cars. We’ve doubled efficiency. We’ve got efficiencies in our air conditioning. We’ve got the power-plant rule.

But you’re absolutely correct. We do mobilize normally when we have this kind of threat, and that’s why I’m here in Norfolk: to underscore that this is a national-security threat and we need a broader response.

But given the kind of global chaos you articulated – not to mention that we can foresee the end of cities like Miami as we know it within our children’s lifetimes – it seems to me that we have a long way to go in really thinking about the scale of this threat.

We have a long way to go, because we still have people in the United States Senate who even deny its existence. And how do you mobilize your government in a democracy when part of your democratic process is gridlocked and frozen and, in some cases, ignorant?

Given your characterization of climate change as a national-security threat, when you look at what the Koch brothers and Exxon Mobil are doing – as you know, Exxon Mobil is being investigated by the New York state attorney general for lying to investors about what it knew about climate change—

Absolutely. It’s tobacco – it’s R.J. Reynolds all over again.