In September, students from across Connecticut gathered to seek "emergency action" to address climate change. They join a global uprising of young people urging us older folks to help preserve the planet that they will inherit. Their passion is laudable, but their demands ignore Connecticut's greatest contributor to climate change: our inefficient zoning laws.

During the course of the 20th century, Connecticut's municipalities have made it harder and harder to build small-lot and multifamily housing. Today, on most land in most Connecticut suburbs, one or two acres is required to build a new single-family home. Many municipalities prohibit multifamily housing (housing with three or more units) altogether; almost all others require a "special permit" to allow multifamily housing, in practice giving governments discretion to prohibit permits at will.

Municipalities also often place outrageous land requirements on multifamily housing. Avon, for example, requires 15 acres to build a two-unit residence, although one third of an acre is the minimum for a single-family dwelling. Monroe's requirements are even more extreme, requiring at least 70 acres for multifamily construction, although single-family homes require only one acre. "Only" 20 acres are required in Monroe's "Housing Opportunity District," but density restrictions limit the number of units to 13.

Such restrictions exponentially increase Connecticut's impact on climate change. Large-lot zoning requirements lead to larger house sizes, with all the increased energy costs they involve. Multi-unit dwellings use on average half the energy per unit of single-family detached houses, both because of shared walls and typically smaller unit sizes. Greater housing sprawl, of course, also increases transportation energy use, because it makes communities less walkable and public transportation less efficient. The EPA concludes the greatest energy savings come not from energy-efficient practices within the home, but from locating homes of all types in areas where residents can replace some automobile use with walking or public transport.

For decades, Connecticut zoning laws have pointed in the opposite direction, making it nearly impossible to build the kind of housing that can reduce energy emissions. Fortunately other states and municipalities have provided models we could use to reverse course. Minneapolis recently banned single-family zoning, allowing duplexes and triplexes throughout the city. Closer to home, Hartford has eliminated parking requirements for new construction and encouraged denser building near transit hubs. Given Connecticut's combination of exclusionary suburbs and troubled cities, however, any solution should be statewide. California, for example, is debating a bill that would require duplexes in areas close to transit hubs, job clusters and good schools. Perhaps most relevant to Connecticut, Oregon recently required all municipalities with 10,000 or more residents to permit duplexes on all lots zoned for single-family use.

Any solution will face entrenched municipal resistance. But if we really want to make an impact on climate change, both our young people and our leaders must begin addressing zoning reform.