Urban development is good for the environment. If there is one serious message we can take from Miami Mayor Manny Diaz’s recent State of the City address, it is that.

In his speech, Diaz showed off the “green” reforms his city has implemented of late in an effort to continue painting himself as an environmentalist, a notion laughed at by critics who don’t see his developer-friendly, big-business policies as so good for the environment.

But give Diaz credit for making a good argument. “Traditionally, cities in America were developed as high-density, compact, walkable, mixed-use neighborhoods — think of Washington, D.C., Boston and New York — where neighborhoods connect to form great cities,” reads the text of Diaz’s address, which he delivered on April 26. “But all that changed. We abandoned our cities for the failed promise of the suburbs. We paved our land, destroyed our natural areas, wasted our water resources, spent billions to connect distant neighborhoods, strained municipal budgets and we glorified the automobile.”

His proposed solutions include creating new neighborhoods that bring together workplaces and residences connected by a reliable transit system or within walking distance of each other, or even within the same building. Think of South Beach — where many residents walk or bicycle to their nearby places of employment — writ large. Any new buildings, Diaz continued, would need to be developed in accordance with environmental standards stipulated by Miami 21, a proposed code Diaz is pushing and Miami-based urban planner Elizabeth Plater-Zyberk is designing.

Diaz is right. Much of Florida’s environment won’t be able to sustain further urban sprawl. Florida is a flat, at-sea-level expanse once covered by swamps. A 100-plus-year development boom cleared out many of those wetlands, reducing the once all-imposing marsh to a national park we call the Everglades, and converting the state to a concretized region comfortable for humans. Well, comfortable except for the record-level drought that Florida south of Orlando is now experiencing. If the drought lasts much longer, not only will water-use become more strictly regulated, but the real estate development market in the drier parts of the state will be threatened by calls for a moratorium.

Or maybe it won’t, and the drive to build new cities where none exist will return. In Miami-Dade County’s case, that will mean renewed calls from developers to extend the Urban Development Boundary line, enabling them to build new cities closer, or into, the Everglades on cheap and obtainable land.

Diaz, though, has another plan. Come to Miami and invest there. One thing Diaz deserves credit for is that he has rarely shied away from his policy that more development in Miami is good for everyone.

Just as urban sprawl can harm the environment of a fragile state, so can unrestrained development transform a city into a virtually unlivable space. Already Miami’s road congestion is out of control. And, given that the region is at sea level, a New York-style subway system is out of the question. So how does one fit more buildings into gridlocked Omni and Edgewater? Answer: Bring in an environmentally friendly streetcar system, which also got a mention in Diaz’s speech: “This is why we need to invest in a streetcar system today, like the one we used to have, and we must do this while we can still afford it, rather than leave future Miamians to wonder why we failed to act.”

But that’s the problem: Miami can’t afford it. The system will cost $200 million. It will require substantial funding from the Florida Department of Transportation and the federal government to make it happen. The city has applied for the grants, but with the state of Florida considering massive property tax cuts and the United States still caught in an expensive war in Iraq, there is less money to go around. A larger version of the streetcar system, called the Bay Link, which was to connect South Beach to Omni, was basically killed because federal funds were unattainable for the project.

Perhaps Diaz sensed this, for he later told the Miami Herald, “This is not about today. We can abdicate our obligation to the future, we can turn around and say ‘Ah, let somebody else worry about that,’ but you know we’re going to need it.”

So, yes, urban development in areas where it already exists is environmentally preferable to building new cities southwest of Florida City, Doral or in the Redland.

But Miami won’t be a pleasant environment without the infrastructure to support the projects that are even now being constructed. If Mayor Diaz wants to create a lasting legacy, he should be prepared to find practical alternative transit systems in neighborhoods not connected by Metrorail or Metromover. This could mean rapid transit buses, trackless trollies or even additional traffic lanes — things that could be brought to fruition and paid for fairly soon. It could also mean leaving all the intense development for Miami’s downtown and government center areas, where rail transit already operates. At the very least, it means Diaz should prioritize and focus his lobbying efforts in Tallahassee on getting funding for his light-rail project, instead of on pitching tax breaks for a baseball stadium.

Or Mayor Diaz can remain married to the streetcar idea. Streetcars do sound more environmentally friendly than cars, whether or not they actually come to fruition. And he can continue touting some city reforms such as requiring developers to build “green buildings” (a thing many builders seem to be pouncing on eagerly as a marketing gimmick). He can keep saying he is Miami’s environment-friendly mayor as cranes continue to stretch across the sky. So far the Green Mayor Manny Diaz persona is working on a national level even if it has drawn snickers from cynical locals. And being in his last term as mayor, maybe that’s all that matters.

Comments? E-mail letters@miamisunpost.com.