On this Earth Day, it is worth nothing that we’re more than a year into the Trump administration and the president has failed to act on or even acknowledge the single greatest threat to economic growth and national security facing the United States: climate change.

Post-Hurricane Maria, much of Puerto Rico still lacks basic services, to say nothing of new investments in protective, coastal infrastructure.

Post-Hurricane Harvey, Houston continues to suffer from a lack of coordination — and a surfeit of tension — between the city and state recovery efforts.

Even post-Hurricane Sandy New York remains without a single major built project in response to that storm. The national system for responding to disaster is broken. The national system for anticipating disaster and adapting our communities to a changing climate is non-existent.

As climate change quietly became the most pressing societal concern in the United States, the vacuum of leadership amongst elected officials is placing tens of millions of people and trillions in economic value at risk. This statement isn’t drawn from the rhetoric of radical environmentalists or dystopian futurists; rather, it’s the product of any honest reading of the farming community’s unspoken reality, the urbanism community’s newfound obsession with resilience, the scientific community’s consensus, and, somewhat quietly, the U.S. Armed Forces’ own threat analysis.

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Yet the subject’s conspiratorial treatment by Republicans and its trivialization by Democrats is emblematic of the way its diffuse, slow-developing impacts are felt. Beyond focusing on events like Hurricanes Maria and Harvey, the effects of climate change are difficult to detect in everyday life. It is paradoxically an issue with no clear constituency and one that intersects every major national issue, from racial justice and income inequality to job creation and national security. Climate change will negatively impact almost everyone and neither party has a plan for dealing with it. It is precisely the sort of issue that demands national attention at a time when our federal institutions are broken.

In the absence of congressional or presidential leadership on climate, the military has begun its own internal risk assessment around climate change. As one of the world’s largest landowners, the U.S. military owns and operates a massive real estate portfolio — much of which is ill-prepared for the rising seas, extreme heat and uncertainty that climate change portends. More troubling, climate scientists expect it to spread drought, famine and poverty across much of the globe, destabilizing nations and creating new and unmanageable resource conflicts that will further stressing an already over-extended military.

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Along the nation’s coast, the cost of climate change denialism is placing the vast, productive and vital cluster of shipping lanes, ports, railways and freight movement facilities at tremendous and unnecessary risk. There, the backbone of America’s economy — and perhaps the last vestige of high-paying, private sector union jobs — are imperiled by the threat of tropical storms and rising seas. Each day, more than $4 billion in foreign trade moves through the nation’s coastal infrastructure, including ports, which employ 23 million Americans. Their livelihoods — and the nation’s economy — are at risk, and the President is doing nothing to secure their future.

The bulk of this nation’s agricultural products are carried to market through a labyrinth of freight arteries to coastal ports and, eventually, global markets. Shifts in temperature and precipitation have already begun to affect the viability of farming as we know it in the United States. Rising seas and more intense storm events will similarly impact farmers as their goods become increasingly more difficult and expensive to move.

The most recent and glaring example of this precariousness is Houston’s experience with Harvey last year.

Three of the nation’s largest ports by tonnage rim this region’s shipping channel, creating the second-busiest freight waterway in the nation. Those ports are part of the largest petrochemical processing and storage facility cluster in the United States. They are where most military-grade fuel is refined and stored. Hurricane Harvey, though devastating in terms of precipitation-driven flooding, produced almost no storm surge — an ideal but unusual result that spared the city billions in cleanup and restoration costs.

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The next storm to hit Houston is likely to spread those noxious chemicals and petroleum products across the vast and now completely urbanized plain of Southeast Texas. The result will be an unfathomable environmental and human health catastrophe, one the nation may never be able to undo. But it will also a major threat to military readiness and a massive, trillion-dollar threat to the national economy if flooding disrupts the Houston Ship Channel’s freight operations for months on end.

Even in large, densely-developed coastal cities like New York, Boston and Miami, millions of poor and working-class residents find themselves in housing that’s affordable because it was built in flood-prone areas. It’s not a coincidence that the nation’s already under-built supply of public and affordable housing is disproportionately vulnerable to climate change.

But those cities shouldn’t be our primary concern. Rather, it’s the small and medium-sized cities along the Gulf and Atlantic Coasts where the costs of inaction will be impossible to bear. Without the financial, technical and political capital of the nation’s wealthiest cities, communities like Galveston, Mobile, Ala., and Toms River, N.J., cannot face the challenge without federal resources. Redesigning entire communities is expensive, necessary work.

To do so, the nation needs elected officials who are willing to do more than simply acknowledge the existence of climate change, though that’s a fine place to start. The nation needs politicians who are willing to work with communities to develop plans for the future and to then stake their careers on securing the funding necessary to realize it. Until they do, people’s lives and livelihoods will be at risk.

Fleming is the Research Director of the Ian McHarg Center at the University of Pennsylvania School of Design. He is currently finishing a book for Penn Press entitled “Sinking Cities: The Nature, Design, and Politics of Adaptation along the American Coast.” Randall is a research assistant in the McHarg Center and a graduate student in city planning and historic preservation at the University of Pennsylvania School of Design.